13675335 radio-graphic-atlas-of-skull-and-brain-anatomy-20061120-3540341900-massimo-gallucci-silvia

M. Gallucci • S. Capoccia • A. Catalucci, Radiographic Atlas of Skull and Brain Anatomy

Massimo Gallucci • Silvia Capoccia • Alessia Catalucci

Radiographic Atlas of Skull and Brain Anatomy With 794 Figures

Springer

MASSIMO GALLUCCI

MD, Professor and Chairman, Department of Neuroradiology, University of U Aquila, Italy

SILVIA CAPOCCIA

MD, Senior Staff Radiologist at the S. Maria della Stella Hospital, Orvieto, Italy

ALESSIA CATALUCCI

MD, Senior Staff Radiologist at the S. Salvatore Hospital, L'Aquila, Italy

This edition of Radiographic Atlas of Skull an Brain Anatomy by Gallucci - Capoccia - Catalucci is published by arrangement with Idelson-Gnocchi srl, Naples, Italy

© 2005 CASA EDITRICE IDELSON-GNOCCHI Srl-Editori dal 1908

ISBN-10 3-540-34190-0 Springer-Verlag, Berlin Heidelberg New York ISBN-13 978-3-540-34190-1

Library of Congress Control Number: 2006926503

This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9,1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable for prosecution under the German Copyright Law.

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© Springer-Verlag Berlin Heidelberg 2007 Printed in Germany

The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

Product hability: The pubUshers cannot guarantee the accuracy of any information about the application of operative techniques and medications contained in this book. In every individual case the user must check such information by consulting the relevant literature.

Editor: Dr. Ute Heilmann Desk Editor: Meike Stoeck Production Editor: Joachim W. Schmidt

Cover design: Frido Steinen-Broo, eStudio Calamar, Spain

Typesetting: FotoSatz Pfeifer GmbH, D-82166 Grafelfing Printed on acid-free paper - 24/3150 - 5 4 3 2 1 0

Preface

The English Edition contains a few differences from the first ItaHan Edition, which require an explanation. Firstly, some images, especially some 3D reconstructions, have been modified in order to make them clearer. Secondly, in agreement with the Publisher, we have disowned one of our statements in the preface to the Italian Edition. Namely, we have now added a brief introductory text for each section, by way of explanation to the anatomical and physiological notes. This should make it easier for the reader to understand and refer to this Atlas.

These differences derive from our experience with the previous edition and are meant to be an improvement thereof Hopefully, there will be more editions to follow, so that we may further improve our work and keep ourselves busy on lonesome evenings.

Finally, the improvements in this edition are a reminder to the reader that one should never purchase the first edition of a work.

UAquila, January 2006 The Authors

Preface to the Italian Edition

I have been meaning to publish an atlas of neuroradiologic cranio-encephaHc anatomy for at least the last decade. Normal anatomy has always been of great and charming interest to me. Over the years, while preparing lectures for my students, I have always enjoyed lingering on anatomical details that today are rendered with astonishing realism by routine diagnostic imaging.

To the allure of the images we should add the necessary teamwork with our colleagues and associates, and as I finally found a go-ahead and open-minded publisher in Guido Gnocchi, I decided to pursue this idea.

The project was fulfilled thanks to the constant, friendly willingness of Silvia Capoccia and Alessia Catalucci, without whom the idea would have remained an idea, Mr Gnocchi, whom I had alerted about the idea of an anatomical atlas at least four years ago, would have been disappointed, the atlas would have been shelved, and I would have been credited with something I did not do.

I am, therefore, grateful to Alessia and Silvia (in inverse alphabetical order of surname on the front cover) for carrying out much of the work. I am equally grateful to Massimo Caulo for providing a number of the images of functional studies, and to architect and graphic wizard Mauro Trappolino for solving problems we had with the more complex images.

To myself, besides my own share of this work, remained the most difficult and challenging part: writing the preface and the dedication.

The preface: the following pages contain images but no text, as is fitting for an atlas. We specifically chose not to focus on technical notes or physiological explanations because we believe that the atlas can be referred to for comparison, checking, or for the location of pathologies, and not for an understanding of their functional meaning or clinical expression. This atlas, therefore, is not intended for those who are already experienced in navigating the anatomy and physiopathology of the nervous system. Rather, it is hoped the less experienced will benefit from it. Should this not be the case, we will not return their money, which in any case will be donated to health projects in the Third World.

The dedication: you may have noticed that, in recent years, medical books have appeared without a bibliography, index, or even whole chapters, and yet one element is always present: a dedication. I gather it represents a crucial element and, thus, I must do my best to provide one. Upon perusing available dedications, I noticed that they nearly always involve family members or professional masters. To whom, then, should I dedicate this work? To a great master of mine. Professor AgnoH, who passed away over a decade ago, I have already dedicated a previous work. As for my family, I am not sure that a dedication would be appropriate. They, too, were the recipients of a previous dedication and, to be honest, this kind of gift might not seem totally unselfish: it is less an authentic dedication than an attempt to quench feelings of guilt for depriving one's family of quality time in order to achieve a "higher" goal. Yet at other times, when the goal is not that high, a dedication is an awkward attempt to involve the neglected family in a form of narcissistic care which, as such, does not leave any room for others.

Therefore, if my daughters should someday ask me: "Why on earth did you dedicate to us a book on skulls?" I would be hard-pressed to find an answer. The best reply would be "because I never wrote a book of poetry". That is why, in the hope of succeeding in writing a book of poetry within the next half century to dedicate to my dearest ones, I do not think it is out of place if I dedicate this work to the job of artisans like myself, Alessia, Silvia, and most of those who will consult it.

VIII

Tibetans do not eat meat. Only rarely do they do so, when forced by famine. Folco Maraini wrote (Segreto Tibet, Leonardo da Vinci Publisher, Bari, 1951) that in this case, before they kill the animal, they explain to it the necessity of its sacrifice, and that this will benefit its soul. The animal is also told that the body of its killer will in turn become a meal for other creatures, after its death.

Ce qualcuno sulla cui pelle ho imparato Ce qualcuno per la cui pelle non ho dormito. A questo gioco inevitabile di dare e avere Che caratterizza il nostro mestiere E la nostra vita

(There are some on whose skin 1 learnt There are some for whose skin I did not sleep. To this unavoidable game of give and take That characterizes our job And our lives)

M.G.

Contents

1 - Surface Anatomy 1

A Skull: Plain Film 3

B Skull: Three-Dimensional Computed Tomography 11

C Brain: Three-Dimensional Magnetic Resonance 25

2 - Sectional Anatomy of the Telencephalon 29

A Sagittal Sections 31

B Coronal Sections 45

C Axial Sections 63

3 - Brainstem and Cerebellum 85



C Axial Sections 101

4 - Cranial Nerves and Related Systems 113

A Olfactory Nerve (I) and Olfactory System 115

B Optic Nerve (II), Visual Pathway and Orbit

I Optic Nerve (II), Visual Pathway 119

II Orbit 127

C Oculomotor Nerve (III), Trochlear Nerve (IV), Abducens Nerve (VI) 141

D Trigeminal Nerve (V) 147

E Facial Nerve (VII) and Vestibulo-Cochlear Nerve (VIII), Acoustic and Vestibular Systems, Petrous Pyramid

I Facial Nerve (VII) and Vestibulo-Cochlear Nerve (VIII), Acoustic and Vestibular Systems 157

II Petrous Pyramid: Computed Tomography 171

F Glossopharyngeal Nerve (IX), Vagus Nerve (X), Accessory Nerve (XI), Hypoglossal Nerve (XII) 199

5 - Functional Systems 203

A Motor Systems

I Pyramidal System 205

II Extrapyramidal System: Basal Ganglia; Thalamus




B Sensory Systems I Somatosensory System 243 II Gustatory System 249

C Speech System 253 D Brainstem Pathways and Nuclei 257 E Limbic System and Hippocampus 263 F Commissural and Associative Pathways 275 G Neuroendocrine System 277 H Cerebrospinal Fluid System 289

6 - Vascular Anatomy 297 A Intracranial Arteries 299 B Arterial Vascular Territories 319 C Intracranial Veins 341

Bibiography 353

Subject Index 355

1 Surface Anatomy

2 Short Introduction pp. 3-23.

Surfoce Anatomy

The Skull

The skull can be divided into two portions: neural and facial. The neural skull is made up of 6 bones: frontal, parietal, temporal, occipital, sphenoid and ethmoid. The facial skull comprises 8 different bones. In this chapter, they will be briefly described. Synthetic descriptions of sutures between them and of the skull base foramina will follow.

I. Skull Bones

• frontal bone The frontal bone resembles a cockleshell, and consists of two portions: a vertical portion, the squama, corresponding to the forehead region; and an orbital or horizontal portion, which extends to form the roofs of the orbital and nasal cavities.

• parietal bone The parietal bones form the sides and roof of the cranium. Each bone is irregularly quadrilateral in form.

• temporal bone The temporal bones are situated at the base of the skull. Each consists of five parts: squama, petrous, mastoid, and tympanic parts, and styloid process.

• occipital bone The occipital bone is trapezoid-shaped and situated at the back and lower part of the cranium. It contains a large oval aperture, the foramen magnum, through which the cranial cavity communicates with the vertebral canal. The curved, expanded plate behind the foramen magnum is termed the squama, while the thick part in front of the foramen is called the basilar part.

• sphenoid bone The sphenoid bone is a bone situated at the base of the skull in front of the temporal and basilar parts of the occipital bone. It resembles a bat with open wings. It is divided into a median portion or body, two greater and two lesser wings extending outwards from the sides of the body, and two pterygoid processes which project from it downwards.

• ethmoid bone The ethmoid bone is located at the roof of the nose and separates the nasal cavity from the brain. It is lightweight due to a spongy construction. The ethmoid bone consists of four parts:

- the horizontal "cribriform" plate (lamina cribrosa), part of the cranial base - the vertical "perpendicular" plate (lamina perpendicu-laris), which is part of the nasal septum - the two lateral masses (labyrinths)

• mandible The mandible forms the lower jaw (inferior maxillary bone). It is the largest bone of the face. The mandible consists of a curved, horizontal portion, the body, and two perpendicular portions, the rami, connected with the ends of the body at almost right angles.

• maxilla The maxillae join together to form the whole of the upper jaw. They hold the upper teeth, and are connected to the zygomatic bones on the left and right. They assist in forming the roof of the mouth, the floor and lateral wall of the nose, and the floor of the orbit. They contribute to the formation of two fossae, the infratemporal and pterygopalatine, and two fissures, the inferior orbital and pterygomaxillary. Each bone consists of a body and four processes - zygomatic, frontal, alveolar, and palatine.

• palatine bone The palatine bone is situated at the back part of the nasal cavity between the maxilla and the pterygoid process of the sphenoid bone. It contributes to the walls of three cavities: the floor and lateral wall of the nasal cavity, the roof of the mouth, and the floor of the orbit; it contributes to the formation of the pterygopalatine and pterygoid fossae, and the inferior orbital fissure. The palatine bone consists of a horizontal and a vertical part.

• zygomatic bone The zygomatic bone (zygoma; malar bone) is a paired bone articulated with the maxilla, the temporal bone, and the sphenoid bone. It presents a malar and a temporal surface; four processes, the frontosphenoidal, orbital, maxillary, and temporal; and four borders.

• nasal bone The nasal bones are two small oblong bones, varying in size and form; they are placed side by side at the middle and upper part of the face, and join to form the nose.

• lacrimal bone The smallest and most fragile bone of the face, the lacrimal bone is situated at the front part of the medial wall of the orbit.

• vomer bone The vomer bone is located in the midsagittal line, forms the hind and lower part of the nasal septum, and touches the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones.

• inferior nasal concha The inferior nasal concha is a lamina of spongy bone (concha nasahs inferior; inferior turbinated bone) that extends horizontally along the lateral wall of the nasal cavity.

II. Sutures

- Sagittal - along the midline, between parietal bones - Coronal - between the frontal and parietal bones - Lambdoid - between the parietal and occipital bones - Squamosal - between the parietal and temporal bones - Metopic - between the two frontal bones, prior to the fu

sion of the two into a single bone

III. Skull Base Foramina

The skull base is crossed by several foramina. The following is a list of them and their contents:

- foramen caecum: emissary vein to superior sagittal sinus - foramina of cribriform plate: olfactory nerve bundles - posterior ethmoidal foramen: posterior ethmoidal ar

tery, vein and nerve - optic canal: optic nerve [II], ophthalmic artery - superior orbital fissure:

oculomotor nerve [III] trochlear nerve [IV] lacrimal, frontal and nasociliary branches of ophthalmic nerve [VI]


abducens nerve [VI] superior ophthalmic vein foramen rotundum: maxillary nerve [V2] foramen ovale: mandibular nerve [V3] accessory meningeal artery lesser petrosal nerve (occasionally) foramen spinosum: middle meningeal artery and vein meningeal branch of mandibular nerve foramen lacerum: internal carotid artery internal carotid nerve plexus canal of lesser petrosal nerve canal of greater petrosal nerve internal acoustic canal: facial nerve [VII] vestibulocochlear nerve [VIII] labyrinthine artery jugular foramen: inferior petrosal sinus glossopharyngeal nerve [IX] vagus nerve [X] accessory nerve [XI] sigmoid sinus posterior meningeal artery internal jugular vein hypoglossal canal: hypoglossal nerve [XII] foramen magnum: medulla oblongata vertebral arteries meningeal branches of vertebral arteries spinal roots of accessory nerves.

Lesser wing of sphenoid bone

Innominate line

Orbital border

Ethnnoidal cells or ethmoidal labyrinth

Foramen rotundum

Mandibular condyle

Mastoid process

Odontoid process of axis

Vertical ramus of mandible

Atlanto-axial joint

Horizontal ramus of mandible

Sagittal suture

Frontal sinus

Superior border of petrous pyramid

Nasal septum

Atlanto-occipital joint

Lateral mass of atlas

Axis (body)

Angle of mandible

4 1 Surface Anatomy

Frontal sinus

interior clinoid process

Sphenoidal sinus

Floor of sella turcica

Anterior nasal spine

Hard palate

Outer table

Diploe

Inner table

Vasal imprints

Lambdoid suture

External occipital protuberance

Posterior clinoid process


Frontal sinus

Nasal bones

Malar bone


Alveolar processes -

Mandible

Sphenoethmoidal planum

Maxillary sinus

Hard palate

Hyoid bone

6 1 Surface Anatomy

Sagittal suture

Superior orbital border (roof of the orbit)

Fronto-zygomatic suture

Orbital floor

Zygomatic bone (body)

Maxillary sinus -^

Petrous pyramid of temporal bone -^

Occipital foramen -^

Angle of mandible —

Frontal sinus

Ethmoidal cells

Orbit

Nasal septum

Foramen rotundum

Superior margin of petrous pyramid


k


Mastoid process

Vertical ramus of mandible-


Peduncle and lateral mass of atlas

Spinous process of axis

Angle of mandible

Horizontal ramus of mandible

^m Atlanto-axial articular space

Lateral mass of axis

Lower border of the posterior arch of atlas

8 1 Surface Anatomy

Bregma Vertex

Pterion

Glabella


External acoustic meatus

Gonion

Lambda

_ Asterion

Porion

Inion or external occipital protuberance


Glabella

Nasion


Pogonion —

Gnation ^- _,,, '

10 1 Surface Anatomy

Superior horizontal line

Orbitomeatal line -

V '""^Jtu^^/-

'ISf' 1 w^^

;V ^i: ;

Auricular vertical line

Frankfurt plane

B Skull: Three-Dlmenslonal Computed Tomography 11

iiit'iWVjr*

Frontal bone

Sphenoid bone

Parietal bone

Lacrimal bone

Ethmoid bone

Nasal bones

Temporal bone

t ll^lfePHlli I P Zygomatic bone

^ ^ ^ ^ ^ ^ ^ * ^ ^ Maxillary bone

Mandible

1 2 1 Surface Anatomy

|SH-.

:P : #

^ B Orbital process of the palatine bone

^ ^ Frontal bone

^ ^ Sphenoid bone

' Parietal bone

^ ^ Lacrimal bone

Ethmoid bone

Nasal bones

^ P Temporal bone

^ P Zygomatic bone

^ P Maxillary bone

^ P Mandible

B Skull: Three-Dlmensional Computed Tomography 13

^ * . l t

iiis

; *

B Frontal bone

^ Sphenoid bone

I Parietal bone

^ Lacrimal bone

Ethmoid bone

^ Occipital bone

i Nasal bones

B Temporal bone

B Zygomatic bone

A Maxillary bone

A Mandible


:^t2..l

^i r^^£j

Parietal bone

Temporal bone

Zygomatic bone

Occipital bone

Mandible

^ ' ^ • • • ^ ^ r -

B Skull: Three-Dimensional Computed Tomography 1 5

N

M Frontal bone

^ Sphenoid bone

I I Parietal bone

A Palatine bone

Ethmoid bone

^ Nasal bones

^ Vomer bone

^ ^ Occipital bone

^ Maxillary bone

^ Mandible

^ p Temporal bone


/

Frontal bone

Sphenoid bone

Parietal bone

Ethmoid bone

Temporal bone

Occipital bone

B Skull: Three-Dlmensional Computed Tomography 17

isif? 'r 'f f

\

Frontal bone

Sphenoid bone

Parietal bone

Ethmoid bone

Temporal bone

Occipital bone


Sagittal suture -

Frontal protuberances -

Coronal suture

Maxillo-nasal suture -

Fronto-zygomatic suture -

Maxillo-lacrimal suture

Frontal process of maxillary bone

Alveolar process of maxillary bone


Mental protuberance

Supraorbital incisure

Perpendicular lamina of ethmoid bone

Greater wing of sphenoid bone

Temporal bone

Infraorbital foramen

Zygomatic bone


Mastoid process

Intermaxillary suture

Angle of mandible

Mental foramen

B Skull: Three-Dlmenslonal Computed Tomography 19

Parietal bone

Lambdoid suture

Temporal squama —

Mastoid process

External acoustic meatus

Zygomatic process of temporal bone

Vertex

Bregma

Coronal suture

Frontal bone

Pterion

External side of the greater wing of sphenoid bone

Nasal bone


Zygomatic bone


Alveolar process

Hyoid bone


.«*

Lambdoid suture -

Occipital-mastoid suture

Occipital external protuberance —

Odontoid process of axis —


Atlas

Parietal bone

Occipital bone

Occipital condyle

Styloid process

Angle of mandible



Sella turcica

Internal acoustic meatus

Medial plate of pterygoid process

Hook of pterygoid process

Anterior clinoid process

Frontal sinus

Nasal bones


Palatine process

Hyoid bone


Dorsum sellae

Crista galli

Floor of sella turcica


Greater wing of sphenoid bone

Foramen lacerum —

Petrous pyramid of temporal bone


Jugular foramen

Clivus


Occipital foramen

Lesser wing of sphenoid bone


Foramen rotundum

\ ^u^^ ^ . . - ^ ^ . - - >

\t y

Carotid groove

Foramen spinosus and groove of the middle meningeal artery

Meckel's cave

Foramen ovale

Hypoglossal canal


Superior sagittal sinus groove

Crista galli

'WKr i.' '^

Optic canal


Tuberculum sellae


Spheno-occipital suture


Clivus

'V ' H • ""' #*

^^ Lesser wing of sphenoid bone

— Chiasmatic groove

— Greater wing of sphenoid bone

— Superior orbital fissure

~~ Foramen rotundum

— Petrous pyramid of temporal bone

24 Short Introduction pp. 25-27

The Brain

The brain or encephalon is the cranial part of the neuraxis, distinguished from the spinal cord (medulla spinalis).

The average weight of the brain is about 1380 g in the adult male and about 1250 g in the adult female. The brain increases rapidly during the first four years of life and reaches its maximum weight by about the twentieth year. As age advances, the brain decreases slowly in weight.

It is composed of a rostral portion, the forebrain (prosencephalon), and the truncus cerebri (brainstem). The prosencephalon is formed by two hemispheres (telencephalon) and an impair and median structure. The latter has an anterior part named telencephalon impair, and a posterior part consisting of the diencephalon.

The brainstem is formed by the mesencephalon (midbrain) and the rhombencephalon. The latter is divided into metencephalon (pons and cerebellum) and myelencephalon (medulla oblongata).

The surface of the cerebral hemisphere is characterized by the presence of furrows of two different types: fissures, more prominent and relatively constant in their relationships, and sulci, less deep and more subject to individual variations.

The interhemispheric fissure separates the two hemispheres and hosts the great cerebral falx, a thick meningeal membrane. The sylvian or lateral fissure, quite deep, divides the frontal and parietal lobes from the temporal one. The rolandic or central fissure separates the frontal and parietal lobes. On the medial surface the parieto-occipital fissure divides the precuneus (parietal) from the cuneus (occipital). It extends on the outer aspect of the hemisphere. The border between occipital and temporal lobes on the lateral surface of the brain is less sharp and the division is somewhat arbitrary, passing through the parieto-occipital fissure and the preoccipital notch, in the inferior aspect of the temporal lobe. The preoccipitcd notch is difficult to identify and it is conventionally located 4 cm frontal to the occipital pole.

The insula is hidden inside the sylvian fissure. In order to see it, the frontal and temporal opercula must be opened.

The most relevant feature in the medial aspect of the brain hemisphere is the corpus callosum (see also p. 275). This is the most important interhemispheric commissure, made of 5 parts: the most anterior and inferior one is the ros

trum, immediately dorsal to the anterior commissure (connects portions of middle and inferior temporal gyri): above the rostrum, the genu continues posteriorly with the body of the corpus callosum, which ends in correspondence with the frontal lobe, followed by a notch, the isthmus, and finally the splenium. The corpus callosum is cranially covered by the cingulate gyrus, separated from it by the callosal sulcus. Immediately below its posterior aspect, the fornix is found. This pecuHar structure is an interhemispheric commissure (hypothalamic commissure) comprising two columns that originate from the mammillary bodies. They extend forwards and upwards, toward the center of the corpus callosum, where the columns travel together to form the body of the fornix, while maintaining their fibers separate. Afterwards, they become separate by the commissure of the fornix, and continue backward and then down and forward, towards the anterior commissure and hippocampus, ending in the region of the uncus. The parieto-occipital fissure separates the precuneus and cuneus. The medial aspect of the temporal lobe offers the clear distinction of the uncus of the hippocampus, followed posteriorly by the parahippocampal and the fusiform gyri.

. C Brain: Three-Dimensional Magnetic Resonance 25

F1 = F2 = F3 = Fa = Pa = PI = P2 =

Superior frontal gyrus Middle frontal gyrus Inferior frontal gyrus Ascending frontal gyrus Ascending parietal gyrus Superior parietal gyrus Inferior parietal gyrus

Interhemispheric fissure

Frontal lobe

i;'.y.-;, *i; 1 Central fissure of Rolando

— • !

Parietal lobe

. Parieto-occipital fissure

Occipital lobe

26 1 Surface Anatomy.

Central fissure of Rolando

'^ ^

Frontal lobe -

Lateral fissure of Sylvius ^ " iWtK^ ^''^•V*'

Parietal lobe

F1 = F2 = F3 = 0 =

t op = Fa = Pa = PI = P2 = T1 = T2 = T3 =

Superior frontal gyrus Middle frontal gyrus Inferior frontal gyrus Parsorbitalisof F3 Pars triangularis of F3 Parsopercularisof F3 Ascending frontal gyrus Ascending parietal gyrus Superior parietal gyrus Inferior parietal gyrus Superior temporal gyrus Middle temporal gyrus Inferior temporal gyrus

Parleto-occipital fissure

Occipital lobe

Preoccipital notch

Temporal lobe

. C Brain:Three-Dimensional Magnetic Resonance 27

Interhemispheric fissure

Frontal lobe

Lateral fissure of Sylvius

Temporal lobe

Go = Orbital gyri Gr = Gyrus rectus Tl = Superior temporal gyrus T2 = Middle temporal gyrus T3 = Inferior temporal gyrus

2 Sectional Anatomy of the Telencephalon

30 Short Introduction pp.31- 84

Sectional Anatomy of the Telencephalon

The cross-sectional anatomy of the telencephalon is shown on the following pages. As in almost all other sections of this book, MRI cuts are taken following conventional planes.

Axial cuts are parallel to Talairach^s bicommissural plane (a plane passing through the anterior and posterior commissures, as identified on the midsagittal plane). Coronal cuts are taken perpendicular to the axial ones; sagittal cuts are parallel to the interhemispheric fissure.

On each page the anatomical cut obtained with a Tl-w inversion recovery sequence is fully described. In addition, the same anatomical cut obtained with a T2-w FSE sequence is printed. At the bottom of the page, reference images on the other two planes of the space are shown, with the aim of giving spatial information that can aid in mentally identifying and locating the plane studied.

Cross-sectional anatomy needs no special comments as the anatomical structures are better described in the chapters relative to their functions.

Some comments concern the white matter macroscopic morphology. It consists of fibers, varying in size and arranged in bundles, and may be divided into three distinct systems.

• Projection fibers connect the hemisphere with the lower parts of the brain and the spinal cord.

• Transverse or commissural fibers unite the two hemispheres.

• Association fibers connect different structures in the same hemisphere; in many cases, these are collateral branches of the projection fibers, but others are axons of independent cells.

Axial cross-sections of the brain, when taken above the corpus callosum, show a mass of white matter on each hemisphere referred to as "centrum semiovale". Below it, projection fibers arising from the cortex and directed towards the internal capsule, together with fibers ascending from below towards the cortex, form the "corona radiata". The former occupy a narrow space on each side of the bodies of the lateral ventricles.

Similarly, a special contingent of fibers comes from the lateral geniculate body and reaches the occipital cortex, passing laterally to the occipital horn of the lateral ventricles, be

ing more horizontally oriented. They are the optic radiations, i.e. the final part of the visual pathway.

Finally, in the axial cuts a mild asymmetry between the hemispheres can be observed.

This asymmetry is due to the hemispheric dominance. It is commonly known that 95% of right-handed people have hemispheric dominance on the left, while in 50 to 75% of left-handed individuals the dominant hemisphere is the left one. The dominance is anatomically expressed by a mild hemispheric hypertrophy that is at its most in the occipital region: the left occipital lobe, in such cases, extends slightly farther back than the right one, sometimes scalloping the occipital bone, sometimes bulging on the midline. The left occipital horn is usually longer than the contralateral, and the left transverse venous sinus is lower and smaller than the right one in about 50% of individuals.


Inferior frontal sulcus

Inferior precentral sulcus

Inferior frontal gyrus (F3), pars triangularis

Inferior frontal gyrus (F3), pars operculars

Inferior frontal gyrus (F3), pars orbitalis

Superior temporal gyrus (T1)

Superior temporal sulcus

Middle temporal gyrus (T2)

Precentral gyrus Central sulcus Postcentral gyrus

fe*T ' *=V'" Postcentral sulcus

Supramarginal gyrus

Sulcus intermedius primus (Jensen)

Angular gyrus

Superior temporal sulcus, horizontal posterior segment

Middle occipital gyrus (02), superior part

Lateral occipital sulcus

Lateral temporo-occipital incisure

Inferior temporal gyrus (TB)

Lateral fissure (of Sylvius)

Anterior transverse temporal gyrus

r

32 2 Sectional Anatomy of the Telencephalon

Middle frontal gyrus (F2)

Subcentral gyrus

Precentral gyrus

Central sulcus

Postcentral gyrus



Inferior frontal gyrus (F3), pars opercularis


Inferior frontal gyrus (F3), pars orbitalls

Lateral fissure (of Sylvius)

Superior tennporal gyrus (T1)



Postcentral sulcus

Supramarginal gyrus

Superior temporal sulcus, posterior ascending segment

• " ^ - - ^ j ^ ^ Angular gyrus

X vl ^fS .^-m(f.

" » --.* mi





Inferior temporal sulcus

Inferior temporal gyrus (T3)


'V- -V

^


rN Inferior frontal

sulcus Subcentral

gyrus Precentral

gyrus Central sulcus

Postcentral gyrus

Middle frontal gyrus (F2),

superior part





Lateral orbital sulcus

Lateral orbital gyrus

Superior temporal gyrus (Tl)



Postcentral sulcus

Supramarginal gyrus

'*'-^ "^£^ Angular gyrus

V ,

"f Superior temporal sulcus, posterior

I horizontal segment

^ ^{ Middle occipital gyrus (02),

i:!nt superior part

r 5^ ;T4:^ Lateral occipital S \k-^'^:-^' sulcus

• -^ -\ l- ' ' ' ' '^>v Lateral tem poro-;'*«'^V"i,V^ occipital incisure

Inferior temporal Lateral fissure, of Sylvius, with gyrus (13) middle cerebral artery peripheral branches

- ^ 'MT

i " ,r


- r ^

Middle frontal gyrus (F2), Circular insular Precentral Central Postcentral superior part sulcus gyrus sulcus gyrus



Inferior frontal gyrus {F3), pars triangularis

Middle frontal gyrus (F2),

inferior part

Frontomarginal gyrus


Short insular gyrus

Limen insulae



Intraparietal gyrus

Angular gyrus



Middle occipital gyrus (02), inferior part

Inferior occipital gyrus (03)


Long insular gyrus


Insular central sulcus

Fusiform gyrus (T4)

/

r

•

KM.

^ y^ i- A .

'. % 4.


Central insular sulcus

Circular insular sulcus

Short insular gyrus




Limen insulae




Precentral gyrus

Central sulcus

Postcentral gyrus

Intraparietal sulcus

Angular gyrus



5| Middle occipital gyrus (02), superior part



Inferior occipital (03)

Posterior transverse collateral sulcus

Inferior temporal Fusiform Long insular Temporal horn gyrus (T3) gyrus (T4) gyrus of lateral ventricle

y /^'

t \ i

•

^ - ^ M

<i ^


' • ' ^ " > ; y-Middle frontal

gyrus (F2) Superior frontal

gyrus (F1) Precentral


Postcentral gyrus

Insula

Superior frontopolar gyrus

Inferior frontopolar gyrus

Frontonnarginal gyrus


Lateral fissure, vertical ramus

Posterior orbital gyrus

Superior temporal ^Jf f t gyrus (T1) § V

• f t / Middle temporal

gyrus (T2)


Angular gyrus

Atrium of lateral ventricle


Lunate sulcus, posterior segment



Fourth occipital gyrus (04)



Temporal horn of lateral ventricle

Hippocampus

Fusiform W^xx gyus (T4)

Collateral sulcus (medial temporo-occipital incisure)


Superior frontal Superior sulcus frontal gyrus (Fl)

Precentral gyrus

Central sulcus

Postcentral gyrus




Frontomarginal sulcus


Anterior orbital gyrus


Anterior commissure i ^

f Superior temporal ^

gyrus(T1)


Atrium of lateral ventricle (containing an occasional choroidal cyst)

Superior parietal gyrus (PI)

Superior occipital gyrus (01)

Transverse occipital sulcus

Middle occipital gyrus (02)




Fusiform gyrus (T4)

Parahippocampal gyrus (T5)

Head of hippocampus

Collateral sulcus

y .' / h^

r

*





Middle frontal Superior frontal Precentral Central Postcentral gyrus (F2) gyrus (F1) gyrus sulcus gyrus

Frontomarginal gyrus \|^ p


Medial orbital gyrus


Superior temporal. gyrus (T1) . * ! L-ji«pi3^i»** /f, "^p^^

Superior postcentral sulcus


Superior parietal gyrus(PI)







Head of hippocampus

Fusiform gyrus (T4)

• ^

/

\ ^ ^

%

V

f


/

- < T ^ ' ^ ' > ^

Superior frontal Superior precentral Precentral Central Postcentral gyrus (F1) sulcus gyrus sulcus gyrus

Superior frontal sulcus

Middle frontal gyrus(F2)

Superior frontopolar ) gyrus

f t

Inferior frontopolar ^

gyrus ^ ^





Posterior orbital gyrus Anterior

comnnissure



Parieto-occipital fissure


Tail of hippocampus


Descendens gyrus (ofEcker)



Superior temporal Head Parahippocampal Lingual gyrus (Tl) of hippocampus gyrus (T5) gyrus (05)

V

\

^

S

4 0 2 Sectional Anatomy of the Telencephalon


Superior precentral

sulcus Precentral


Postcentral gyrus

Superior frontal gyrus (F1)





Posterior orbital gyrus ^\

Head of hippocampus

Cingulate sulcus, marginal segment

• ' ^ J Supenor parietal gyrus (PI)


Superior occipital Mr^* gyusioi

Collateral sulcus —^ (medial temporo-

occipital incisure)


Calcarine fissure

g Inferior occipital gyrus (03)

;^J^ Lingual ^ ^ gyrus (05)

of hippocampus Parahippocampal

gyrus (T5) Posterior transverse

collateral sulcus

/

Vv

V

A


Cingulate gyrus

Cingulate sulcus

Precentral gyrus

Central sulcus

Postcentral gyrus

Superior frontal gyrus (FV

Corpus callosum

Frontal horn of lateral ventricle

Frontopolar gyrus

Gyrus rectus and olfactory sulcus

Nucleus accumbens

Optic nerve

j Cingulate sulcus, marginal segment

*"'*^%^' Superior parietal ^ . A T ? - : . gyrus (PI)

%i^' Transverse parietal sulcus

^ - J ^ Precuneus (PI)



T^ d Cuneus (06)

Calcarine fissure

Anterior commissure Isthmus Tail of hippocampus Crus of fornix

''^^' Lingual """^^ gyrus (05)

^

^ '•" A

^

^%


Cingulate gyrus

Cingulate sulcus

Precentral gyrus

Central sulcus

Postcentral gyrus



Frontopolar gyrus

Supraorbital sulcus —^

Corpus callosunn, genu ^r

Gyrus rectus

Nucleus accumbens

Anterior commissure

Optic tract

Crus of fornix

^^\*'îî-^'''^<'%i^ \ •" i > Cingulate sulcus, ^ in^.^."' ^ ^ t p ^ l ^ 2 i > ^ marginal segment

^ % # ' ^ Superior parietal •** ^'î^' gyrus

/^;^ Transverse parietal * '"^ ' sulcus

Precuneus(PI)



Cuneus (06)

^ Anterior calcarine •^ sulcus

''Wi- Calcarine fissure

I f s™ Isthmus Corpus callosum,

splenium

«-r*.

V

* c


Cingulate gyrus

Cingulate Precentral Central sulcus gyrus sulcus

Postcentral gyrus


Lateral ventricle

Corpus callosum, ) f genu ^ ^

Frontopolar gyrus

Supraorbital sulcus

Gyrus rectus

Paraterminal gyrus , (septal nuclei) |5^*

^ r%^;,^^^>y ^ , ^ ^ , j ^ Cjpgulate SUlCUS,

T ^ ' \ ^ ^ ^ - . . ^ . . . "^ ^^%^,% marginal segment

Transverse parietal

' i ^ '^" S u pe r i o r pa r i eta I %^i^-^' gyrus (PI)

Optic nerve and chiasm


Cuneus (06)

Corpus callosum, isthmus

\ ,v Calcarine fissure

1 ^ Lingual ^lvi gyus (05)

• i l i ; : * ? ^ k . , - X . i : ^ ' ^ ! ^ ^ . P - ' \ r l-^-'^ , ^ ^ | ^ splenium

Anterior Column Fornix Superior commissure offornix colliculus

\

-5r-m J- %

„*«^4


Corpus callosum, Cingulate body gyrus

Cingulate Corpus callosum, Precentral sulcus isthmus gyrus

Superior frontal gyrus (Fl)

Lateral ventricle and septum pellucidum

Corpus callosum, ^\i / genu ^ / ^ *

Frontopolar gyrus

Supraorbital sulcus

Corpus callosum, rostrum

Gyrus rectus

Subcallosal gyrus

Paraterminal gyrus / j (septal nuclei) |

" ' " ^ ^ ^ i . * ! ? ^ ^ ^ ^ < 'ngulate sulcus, ^^5^ - ' ^ "* ' ^ ' i J ^ marginal segment

> ^ • ' »•'5^ st Superior parietal ^^ %'• i ^ gyrus (PI)

\ A • '%^ Subparietal sulcus

T


Cuneus (06)

Calcarine fissure

W \ , ^ |v Corpus callosum, X 5 splenium

I W „ \ .^^.^^^^ "m Lingual "II- ' %' -, '" ^ '^^^^:^'"* ^^^' gyrus(C

Optic chiasm

Mammillary body

Fornix Posterior commissure

gyrus (05)

Pineal gland


Superior sagittal sinus

Superior frontal ^ J gyrus (F1) ^


Middle frontal gyrus(F2)


Inferior frontal gyrus (F3)

Olfactory sulcus

Superior rectus muscle

Lateral rectus ^ ^ muscle ' ^ v l

Medial rectus y^'A muscle #""'""'

Inferior rectus muscle

Olfactory bulb Gyrus rectus

Longitudinal fissure

Cingulate gyrus

Frontal lobe

. Transverse (or arcuate) orbital sulcus


& ' ^ Anterior orbital gyrus

:; Medial orbital gyrus

Optic nerve

• • L

Pv

7 : ^ • a *JI'4» ^




Pericallosal artery

Frontal lobe


Inferior frontal gyrus (F3),

pars orbitalis

Olfactory sulcus

Cingulate sulcus

Gyrus rectus




Cingulate sulcus

Cingulate gyrus




Medial orbital gyrus Superior temporal gyrus (T1)

. -" r ••


K Superior frontal >a . ^i^ f^ .:;• ,^> i

sulcus ^•... y^r '•••^\. ' '•-'


Middle frontal

Frontal lobe -

-- 'H'"*


Lateral fissure (of Sylvius),

horizontal ramus




Gyrus rectus


Cingulate sulcus

Cingulate gyrus

Corpus callosunn, genu




Middle temporal gyrus(T2)

Olfactory sulcus







Sulcus of corpus callosum


Short insular gyrus




Inferior temporal gyrus (Y3)


Cingulate sulcus

Cingulate gyrus

Corpus callosum, body



Frontal operculum



\ Superior temporal sulcus


Gyrus rectus

Olfactory sulcus Optic nerve

^

B Coronal Sections 4 9

>

Superior frontal ^'•-i0''f^kr^:i^i^:'.J-^--^^'-'-.Ji^'^t']-t f •'; ,-^4 • • . ; • ; - - » - .-v:^.- ••-^ r •; - <• gyrus(FI) H i $ | * ^ M J r * i ^ v l ^ ' ^ * ' " " " ' ^ -•

Superior frontal |. :=/^M^SisiC—--*.'^



Circular insular j^-^^t sulcus i ^







Corona radiata


Frontal operculum

Septum pellucidum

Short insular gyrus


Anterior cerebral artery

Optic nerve


Internal carotid artery

^ < .

\i

A.



Middle frontal #-;S|: | !S^> gyrus (F2) - ^ i ^ I ^ t r f r " ^

Corpus callosunn, body j

Superior precentral sulcus ' ^ Jt

Frontal horn ^ | * of lateral ventricle

Short insular gyrus

Superior temporal gyrus (TD


Middle temporal ^ ^ gyrus (T2)


Uncus

Optic chiasm Pituitary gland

Septum pellucidum

Paraterminal gyrus (septal nuclei)

Precentral gyrus

Central or rolandic operculum


Middle cerebral artery

^ Internal carotid artery

Pituitary stalk

fr*

r





Superior precentral sulcus

Precentral gyrus

Subcentral gyrus


Short insular gyrus

Long insular gyrus

Anterior perforated substance

Anterior commissure

Optic recess of the third ventricle

Entorhinal area Fusiform gyrus (T4)


Cingulate sulcus

Cingulate gyrus


Corona radiata


Column of fornix




^ Superior temporal gyrus (Tl)

^ Middle temporal gyrus (T2)


Gyrus ambiens


»i >n.


^>



Corona radiata

Body of fornix

Third ventricle


Short insular gyrus

Long insular gyrus

Semilunar gyrus

Hippocampus

Optic tract

Basilar artery

Superior frontal sulcus Middle frontal gyrus (F2)

Gyrus ambiens Entorhinal area Collateral sulcus (medial temporo-occipital incisure)


Precentral gyrus


Subcentral gyrus









Fusiform gyrus (T4)

/

^f


^ ^

Cingulate sulcus ^ ^ ^ j

CIngulate gyrus

Body of fornix

Body of lateral ventricle

,r -"* » •t-. • « * ; ; * , . » * -

/

Third ventricle

Short insular gyrus

Long insular gyrus

Hippocampus


Vertebral arteries - *

Parahippocampal gyrus (T5) Collateral sulcus (medial temporo-occipital incisure)





Precentral gyrus








Lateral occipitotemporal sulcus


Fusiform gyrus (T4)

> ^

» • ^

Af^t4i ,^-_


Superior sagittal sinus Longitudinal fissure


Precentral gyrus

Central sulcus

Postcentral gyrus



Posterior transverse temporal gyrus




Middle temporal / gyrus n'2)

Inferior temporal / sulcus

Inferior temporal / gyrus (T3) ^ 4


Cingulate sulcus

Cingulate gyrus

Corona radiata



' Circular insular * sulcus

Short insular gyrus

Long insular gyrus

Third ventricle

Head of hippocampus

Lateral temporo-occipital sulcus Fusiform gyrus (T4) Parahippocampal gyrus (T5)

/

i

#-r ^


Internal cerebral vein

Cingulate gyrus

Corpus callosum, - ^ isthmus

Body of lateral j J ; ' / ventricle ^ ^ ^

Fornix

Lateral fissure . of Sylvius 1

Corona radiata

Tennporal lobe

Hippocampus

Superior colliculus

Cerebral aqueduct X f%.. | ' * * ^ ' % OfSvlviUS " * ' * ^ ^ * " % * ' ' . ^ ' of Sylvius 1. -^


Precentral gyrus

Central gyrus

Postcentral gyrus

^ - - ^ Intraparietal sulcus

Cingulate sulcus

Supramarginal gyrus

Parietal operculum

Superior temporal gyrus CTl)




Fusiform gyrus (T4)

'-^ Parahippocampal gyrus (T5)

m-^m. w


/


Precentral gyrus

Central sulcus

Postcentral gyrus


Supramarginal gyrus

Lateral fissure of Sylvius \^

Planum temporale

Superior temporal gyrus CTI)


Tail of hippocampus

Inferior temporal / | y gyrus CT3)

Lateral temporo-occipital

sulcus

Fusiform gyrus (T4)

Cingulate sulcus

Cingulate gyrus

Corpus callosum, splenium


Fornix

Cistern of the transverse fissure

Pineal gland

Superior colliculus

Inferior colliculus

Fourth ventricle

Median sulcus of fourth ventricle



T

4


^

Precentral gyrus

Central sulcus

Postcentral gyrus


Supramarginal gyrus

Choroid plexus of lateral ventricle

Superior temporal ^ -4 gyrus (T1) I

Isthmus

Middle temporal gyrus CT2)

Inferior temporal gyrus CT3)


sulcus

Fusiform gyrus (T4)

Paracentral lobule


Parietal lobe

.—I- Cingulate gyrus

Sulcus of corpus callosum

f Lateral fissure s of Sylvius



# , Tail of hippocampus

> ^ ic. ^ Quadrigeminal

'^ s . . cistern


Parahippocampal gyrus (T5) «/v


' \


Paracentral lobule

Subparietal sulcus

Occipital horn « of lateral ventricle ^ ^

Anterior calcarine sulcus



Inferior temporal

Inferior lingual >^' " ' gyrus (05)

Central sulcus

Postcentral gyrus


Cingulate sulcus

Cingulate gyrus

Supramarginal gyrus


Angular gyrus

' * \ Superior temporal sulcus

^ , Optic radiations

. Lateral temporo-occipital sulcus

Fusiform gyrus (T4)


/ . \ A


< I

(Jfcv

Paracentral lobule

Postcentral gyrus


T ' Inferior parietal ^^.^^f

gyrus (P2) i '


Angular g y r u s - ^ f

Occipital horn _ „ of lateral ventricle C t




sulcus

Fusiform gyrus (T4)

Central sulcus

Cingulate gyrus

Anterior calcarine sulcus


Optic radiations

Superior lingual gyrus (05)

Lingual sulcus

Cistern of the great cerebral vein (of Galen)


Inferior lingual gyrus (05)

/


Superior parietal gyrus (P1)

Optic radiations

Parleto-occipital fissure



PP^n^^..^;^H^^P^ Intraparietal sulcus

-sTi * Angular gyrus

^ Precuneus (PI)



_, Cuneus (06)



^ ^.f5 Lateral temporo-^ i C occipital sulcus

Fusiform gyrus (04)


/

V

^

^ • ' . . 5 '3 : 4 /

/


Cuneus (06)

Angular gyrus



Inferior occipital sulcus

Inferior occipital gyrus(03)

Fusiform gyrus (04)


vf"'ijS- Intraparietal sulcus

Precuneus(PI)


Calcarine fissure





^ .

•.*


t r\y^ X

bS.t'^^:?*^ft?fe>r;''^'€i^S ^ ^ ^ ^ M ^ ^ i ^ ' m ' i ^ m : ^ ^ •:• V- . i • . Superiorparietal

Precuneus (PI)

Cuneus (06)

Calcarine fissure



gyrus(PI)


Angular gyrus


. Superior temporal sulcus




Inferior occipital sulcus


V

C Axial Sections 63

Superior temporal gyrus CT1) |

Middle temporal gyrus (Y2)

Gasserian ganglion

Fourth ventricle

r V

> ' ^ - ,


Superior temporal gyrus CT1)

Middle temporal gyrus (12)


Fusiform gyrus (T4) ^

Collateral sulcus ^ (medial occipito

temporal sulcus)

Parahippocampal gyrus (T5); piriform lobe, entorhinal area

ii^m^m-

\

^

0

/

C Axial Sections 65


Parahippocampal gyrus (T5) uncus \

Middle temporal ^ gyrus CT2) ^ ^

temporo-occipital ~~i incisure I

Fusiform gyrus (T4)




Internal carotid % artery


].\^\W*^,t^- ^'u •..•-

/

ii-f^*- '•'4: >™=


Superior temporal gyrus CTI



Fusiform gyrus ([A)

Temporo-occipital ^ fissure \ # €


Fusiform gyrus (04)

Inferior occipital _^ gyrus (03)

Descendens gyrus j (ofEcker) '

Basilar artery


Head of hippocampus


r - r J* ^ Parahippocampal * / ' gyrus (T5)

* r'.s

' ' ^ > .

•> / i '

> -

r ' :7

C Axial Sections 67

Optic nerve

Superior temporal gyrus (TV

Piriform lobe, entorhinal area

Middle temporal i gyrus (T2)

Fusiform gyrus CT4)

Inferior temporal gyrus CT3)

Temporo-occipital fissure

Fusiform gyrus (04)


Inferior lingual ^. gyrus (05) f

Jr^^ j i ^ : Basilar artery

Head of hippocampus



Cerebral aqueduct of Sylvius



\

' . \ V i

/


Gyrus rectus

Optic chiasm

Olfactory trigonum

Piriform lobe, entorhinal area

Head of hippocampus

Parahippocampal gyrus CT5)

Collateral sulcus


\-.,

Calcarine fissure -^^^^'^A _ ^ I M I I I ^ ^ ^ '


Retrocalcarine sulcus

Descendens gyrus J^ ***-' \. (ofEcker) \ 5 l ' : « <

Olfactory sulcus



f* Crus cerebri

*' Superior temporal ^ sulcus



- ^ Inferior colliculus


Temporo-occipital fissure

Fusiform gyrus (04)



/ '

X

If /

I -•

'•1 ej

C Axial Sections 69

Gyrus rectus

Olfactory trigonum


Head of hippocampus



Middle temporal *^ gyrus CT2) ^



Calcarine fissure

Cuneus (06)


'^f^^l^-^ '--'^H *V OI 3Ctory sulcus

"^^J^"^.^ Medial orbital gyrus

^ * ^ Middle cerebral artery \ ^ ^ ^ - in the lateral fissure

% Lateral fissure < of Sylvius

Optic tract '. i

' '— Mammillary body

I Parahippocampal " T ' gyrus (T5)

Collateral sulcus -T (medial temporo-il occipital incisure)

Fusiform gyrus (04)



^i- r

1 .

1

^^^47 ' --^J




Posterior orbital gyrus . ^

Lateral fissure W % of Sylvius

Superior temporal *? * gyrus (T1

Superior temporal % sulcus ^ ^ ^

Middle temporal gyrus (T2) J ,

I Anterior temporal

sulcus

Straight sinus

Cuneus(06) *^*f%f4'

Gyrus rectus


Middle occipital gyrus (02) ^ ^ ^ ^ ^

^ J^>*^r

^ r Subcallosal gyrus

Insula

Superior colliculus

Lingual sulcus

Occipital horn of lateral ventricle

Calcarine fissure

Retrocalcarine sulcus



^ 1 ^

{'•%.

.C ^ • i .

X i

W I t

.\i

"}

^

^- HM

C Axial Sections 71

Anterior orbital ^ gyrus





Superior temporal % sulcus r j

4 Middle temporal

gyrus (T2)

Optic radiations -^

Occipital horn of lateral ventricle




Cingulate gyrus

^1^5^ Subcallosal gyrus

Anterior commissure

Posterior commissure

Tail of hippocampus

" Wt Parieto-occipital fissure

Isthmus (retrosplenial cortex)

Calcar avis

Calcarine fissure

Cuneus (06)

/ ^ ^

r '*

F

v \

r Ji i f

r - i

fi M

111,

I

-iC? • • '^4f iW S % ¥'

- ^ '


\- ^



Inferior frontal gyrus ^ # t e ' ' (F3), pars orbitalis - i * . '^%

ph .._ Inferior frontal gyrus ' |> ^ ^ . (F3), pars opercularis ^' "' ^

Insula


Habenular nucleus ^ ^ | ^ '

Superior temporal £1 gyrus CT1) f *


Tail of hippocampus

Middle temporal gyrus (T2) §

Optic radiations

Middle occipital gyrus (02) - i : * * ^ ^ ' -

Superior occipital , . ^ * | l j ^ ^^^ J^ gyrus (01) ^^f'^''"^f-s'*••


Superior frontal gyrus(Fl)

Cingulate sulcus

Cinguiate gyrus

Subcallosal gyrus



Fornix, body




Isthmus (retrosplenial cortex)

Parieto-occipitai fissure

Calcarine fissure

Cuneus (06)

A

\ :

^

/'l

A 1

"5 V

/

C Axial Sections 73

/ itr -

Superior frontal gyrus (Fl]

Middle frontal gyrus(F2



Precentral gyrus

Central sulcus

Postcentral gyrus

Insula

^ . \^^ *V ! .

Lateral fissure %, of Sylvius ^~^Yl

Transverse temporal__^ gyrus V.



Optic radiations



Cingulate sulcus

Cingulate gyrus

Corpus callosum, genu


Vertical ramus ->— -— of lateral fissure ' ^ * ^ of Sylvius

•"^ Septum pellucidum

' ' ^ Fornix, body


Crusfornicis




j ^ Cingulate gyrus

^ Cuneus (06)


Calcarine fissure

A r ^

A • \

V \

: Y \ /


^' i \






Precentral gyrus

Central sulcus

Insula

Postcentral gyrus



Middle temporal gyrus (02)

Transverse temporal sulcus



Cingulate sulcus

Cingulate gyrus

Corpus callosum, genu


Vertical ramus lateral fissure

of Sylvius

~ - Fornix, body

Internal cerebral \

Choroid plexus of lateral ventricle



Cingulate gyrus

Precuneus(PI)

Parieto-occipital -*» fissure

Cuneus (06)

I

\

r \

^

\ I I *

^"f r^

{

^

^ : % - - ^

C Axial Sections 75




Vertical ramus of lateral fissure of Sylvius



Precentral gyrus

Central sulcus

Postcentral gyrus




Transverse occipital gyrus


Cuneus (06)

Septum pellucidum

"*t - Corona radiata


Corpus callosum, 'i; splenium

^^ Cingulate gyrus

'tl^

h • a?* !^ Parieto-occipital ; ' ' ^ « i \ | | fissure

>•vS^^^:•::^:^^ .:" ^^^"^^ Precuneus (P1)

/

A

r

>

/ N

l l '

A


Cingulate sulcus

Corona radiata

Precentral sulcus

Inferior precentral gyrus

Central sulcus

Postcentral gyrus . J ^ ^

Supramarginal gyrus





Lateral fissure, I x posterior segment

Supramarginal gyrus

Superior temporal ^ sulcus

^ Inferior frontal V sulcus

^ Inferior frontal - gyrus (F3)

Cingulate gyrus

Corpus callosum

^^28» ^ ^ody of lateral / ' 3 ventricle

Intraoccipital sulcus ^-i~-t^A^

Superior sagittal f - JY^ - ' L l ; 'i'';•, " * ' ? • * . * '••iPjj*.,'? _,, •i-r.'- '.


Cingulate gyrus

Precuneus (PI)


^ \ ' V

/ •

i /

/

• ^ i l ^ >

f ^

-1

[T;- I V 'M-i S f r j i * '«;••;•

A

- t

C Axial Sections 77



Middle frontal sulcus



Precentral gyrus --

Central sulcus -

Postcentral gyrus ^ 1 I

Supramarginal gyrus ' ^ ^

Sulcus intermedius primus (of Jensen)

Angular gyrus


Angular gyrus



%'^•?^ e^ *^ i;- . Cingulate sulcus

Cingulate gyrus

f \ Corpus callosum

^ Centrum semiovale

Cingulate gyrus

Subparietal sulcus

Precuneus (PI)

^.,,,.iS#;^l|:;'^. •S-' -? Superior parietal gyrus (PI)

V >

\

/

4^-





Precentral gyrus

Central sulcus

Postcentral gyrus

Suprannarginal gyrus

Sulcus intermedius primus (of Jensen)

Angular gyrus


Angular gyrus


Superior frontal A ' ^ * - t gyrus (Fl)

Cingulate sulcus

Cingulate gyrus

Centrum semiovale

Cingulate gyrus

Precuneus(PI)

/

• ^

i k

4^

> ^

i

'''-'-' ^ ifi / i

^ flH

^fl^B ^H

I '*> MJ^B^'^IB

.'w^HII^^^^I

" ^ ?i s9

81

^ E K

* :•""• •"•' • " ' \

HHK K^' P--^ Jr •

C Axial Sections 79



Precentral sulcus

Precentral gyrus

Central sulcus

Postcentral gyrus

Supramarginal gyrus

Superior temporal sulcus, ascendent segment

Angular gyrus



Cingulate sulcus

Cingulate gyrus

Central sulcus

Cingulate sulcus

Precuneus(PI)

-y ^

>

^ ^

• ^ '

• / -V <VW<

m I W r ''I

I '"W -J ''' .




Middle frontal gyrus {F2)


Precentral gyrus

Central sulcus

Postcentral gyrus

Supranriarginal gyrus

Postcentral gyrus

; &.» iffiiAjigSaL ^RuaMs

Superior parietal gyrus(PI) |


% ^ ^ W Cingulate sulcus, m .«fl*4a marginal segment

Central sulcus

Precuneus(PI)

#^ Superior parietal gyrus(PI)

r rK ^

A _ k

1 1 S ^ 1 ^ ^ • r # %' [ ' " » ""^^KK^"-

•: I <«

C Axial Sections 81




Central sulcus

Precentral gyrus

Postcentral gyrus


Superior sagittal gyrus (PI)

^ ^ " ' T ^ Superior sagittal sinus

Paracentral lobule

Cingulate sulcus, O r ^ marginal segment

Precuneus (PI)

^ ^ - 2 1 ^ ^ ^ f^ Superior sagittal sinus



Middle frontal gyrus (F2) --^




Superior frontal _ » p" gyrus (F1) ^ f ;f

Precentral gyrus

Central sulcus

Postcentral gyrus


Superior parietal / ! gyrus (PI) l

Paracentral sulcus

Paracentral lobule


Precuneus (PI)

r r -

F

'••r^-

•* I ^"*,

i

:s.

y

i-i

C Axial Sections 83


Middle frontal gyrus (F2) \ ^

f Superior

precentral sulcus \ .

Precentral gyrus

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3 Brainstem and Cerebellum


Brainstem and Cerebellum

Brainstem and cerebellum are the contents of the posterior fossa, delimited superiorly by the tentorium cerebelli.

The brainstem comprises the midbrain, pons and medulla oblongata. It is directely connected with the diencephalon, composed by thalamus, pineal body, posterior commissure, habenula, and stria medullaris. From anterior to posterior it can be divided into pes, tegmentum and tectum. The tectum of the brainstem is represented by the quadrigeminal plate, while the tectum of the pons and medulla is the cerebellum. The main pathways and nuclei of the brainstem are described in chapters 4 and 5.

I. Midbrain

The midbrain is about 2 cm in length. The posterior part is represented by the tectum, or quadrigeminal plate. This contains two pairs of tubercles (superior and inferior), also termed collides. They are separated from the tegmentum by a virtual plane passing through the cerebral aqueduct of Sylvius. In front of the tegmentum, the pes of the brainstem is constituted of the cerebral peduncles, also called crura, two thick bundles of fibers diverging upward from below, rostrally limited by the substantia nigra. Between them, the interpeduncular fossa is found. Anteriorly, it is limited by the two mammillary bodies (part of the hypothalamus), while in its depth is the posterior perforated substance through which perforating arteries pass.

II. Pons

The pons is the thicker portion of the brainstem of about 25-30 mm in length. It bulges from midbrain and medulla and is separated from them by the superior and inferior pontine sulci. It is posteriorly covered by the cerebellum, united to it by means of the middle cerebellar peduncles (brachia pon-tis).

III. Medulla Oblongata

The medulla is the lowest part of the brainstem. It continues caudally with the spinal cord. The cord's sulci are present even in the medulla, where they are more prominent.

These are: the median (anterior) sulcus, which disappears at the level of the pyramidal decussation, and the anterolateral (preoli-vary) sulcus, through which the hypoglossal nerve emerges. The eminence between the median and anterolateral sulcus is called the pyramid and hosts the motor fibers of the pyramidal tract. Lateral to the anterolateral sulcus is the olive. Posterior to the olive, the fossetta lateralis is found. This region is supplied by the lateral medullar arteries, most of which come from the postero-inferior cerebellar artery. Infarct of this area is responsible for the Wallenberg syndrome. Posterior to this area, the inferior cerebellar peduncle (corpus restiforme - restiform body) is found.

IV. Cerebellum

The cerebellum consists of two hemispheres and a median structure: the vermis. On the superior surface, there is no clear separation between the hemispheres. In the sagittal cuts, nine segments and two sulci are recognizable. The first segment, lingual, is adjacent to the superior medullary velum (Vieussen's valve), a membrane that delimites superiorly the fourth ventricle. The nodulus is against the inferior medullary velum, which delimites the ventricle inferiorly.

The cerebellar hemispheres are made up of a thick core of white matter (corpus medullaris) covered by the cerebellar cortex. This presents some fissures, of which the most important is the horizontal one that divides the cerebellar hemispheres into two lobi: anterior and posterior. Other fissures subdivide the lobi into lobuli, and these into folia.

Within the white matter of the cerebellum, four gray nuclei are recognized, around and close to the posterior aspect of the fourth ventricle: fastigial, dentate, globose and embo-liform nuclei.

The cerebellum is attached to the brainstem by three bridges: the superior, middle and inferior cerebellar peduncles. The superior cerebellar peduncle (brachium conjunc-tivum) is thin, oblique, vertically and mid-laterally oriented, starting immediately below the inferior colliculum. It follows the velum medullaris superior. The fibers of the superior cerebellar peduncles decussate in the midbrain, and most of them end at the opposite red nucleus. The middle cerebellar peduncle is the biggest cerebellar bridge, and most of the pathways from and to the cerebellum pass through it.

The inferior cerebellar peduncle (restiform body) contains fibers from the medulla and spinal cord. It is thin, originates from the dorsolateral aspect of the upper medulla oblongata, ascends and diverges before entering the cerebellum. Phylogenetically, the cerebellum is divided into three portions: archi, paleo, and neo-cerebellum. The archicerebel-lum, constituted by flocculus and nodulus, is mostly devoted to the maintenance of orthostatic equilibrium. The paleo-cerebellum (amygdala, pyramis, uvula and anterior lobe) governs proprioceptive stimuli coming from muscles and articulations. The neocerebellum includes most of the cerebellar hemisphere and the intermediate portion of the vermis; it seems mostly devoted to the finest regulation of motoricity in both voluntary and involuntary movements.


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88 3 Brainstem and Cerebellum

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94 3 Brainstem and Cerebellum.

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9 8 3 Brainstem and Cerebellum.

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4 Cranial Nerves and Related Systems


Olfactory Nerve and System

The olfactory epithelium is located in the mucosa of the superior nasal concha, and takes up about 2.5 cm^ Inside the olfactory mucosa, olfactory cells are located. They are the peripheral receptors that transmit pulses to the olfactory neurons. The latter are about 6,000,000 bipolar cells (Schulze's cells) distributed inside the epithelium. Their dendrites group together in several filaments which constitute the true olfactory nerves; they cross the cribriform plate of the ethmoid bone and reach the olfactory bulb. The olfactory bulb is a gray matter mass, an evagination of the telencephalon, located between the gyrus rectus and the cribriform plate, containing neurons termed "mitral cells". Their dendrites continue in the olfactory tract, which terminates with the olfactory trigone and tuberculum, in correspondence with the anterior perforated substance. Here, a group of dendrites cross the midline through the anterior commissure and join the contralateral fibers. Before ending, two striae diverge: the lateral olfactory stria, connected with the lateral olfactory nucleus and directed to the amygdaloid body, and the medial olfactory stria, directed to the septal nuclei and hypo-thamalus. Cortical projections of the olfactory function are identified mostly in the prepiriform and entorhinal cortex.

of the calcarine fissure, extending to the adjacent cortex (area 17). Visual information is topographically oriented. The right visual field, for instance, activates neurons of the left retina (medial in the left eye, lateral in the right one). The pulse is then transmitted to the left geniculate body and the left occipital cortex. The upper portions of the visual field are laterally projected in the geniculate body and become inferior in optic radiation and pericalcarine cortex.

Optic Nerve, Visual Pathway and Orbit

I. Optic Nerve and Visual Pathway

Similarly to the olfactory system, the optic nerve is not a peripheral nerve, as it is mostly an evagination of the telencephalon. Retinic photoreceptors, cones and rods, relay the signal for further processing to other retinic neurons: bipolar cells, horizontal cells, amacrine cells, retinal ganglion cells, and interplexiform cells. Axons from the gangHon cells form the optic nerve. The potentials generated are transmitted via the optic nerve to the lateral geniculate nucleus (visual information), superior colliculus (somatic reflexes), and pretectal areas (autonomic reflexes). In mammals, visual information is relayed to the thalamic lateral geniculate body, from which optic information is directed to the primary visual cortex through the geniculo-striate projection, or optic radiation. In humans, the cortical area surrounds both walls


Medial Olfactory Olfactory olfactory stria tract bulb

Olfactory tubercle

Lateral olfactory stria

Diagonal band

Anterior commissure

Inferior thalamic peduncle

Medial telencephalic fasciculus

Stria medullaris of thalamus

Medial nucleus of thalamus

Habenular commissure

Habenular nucleus

Lateral area of hypothalamus

Semilunar gyrus

Gyrus ambiens

Entorhinal area

__ Anterior perforated substance

— Anterior nucleus

^ Lateral nucleus

^ Central nucleus

"^ Medial nucleus

^^ Basal nucleus (accessorius)

Cortical nucleus

Amygdaloid body

Ventral amygdalofugal Stria fibers terminalis

116 4 Cranial Nerves and Related Systems

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B Optic Nerve (II), Visual Pathway and Orbit 119

Eyeball

Optic nerve

Optic chiasm

Optic tract

Optic radiation, temporal knee

Optic radiation

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Optic tract, medial root

Optic tract, lateral root


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Region of activation obtained during visual stimulation white black and white drawings. (Courtesy of Massimo Caulo, MD, PhD, ITAB, Chieti, Italy)

126 Short introduction pp. 127-139

II. Orbit and Contents

In this chapter the anatomy of the orbit will be divided as follows: Bony anatomy; extrinsic eye muscles; eyeball; lacrimal gland and system; vessels.

11.1. Bony Anatomy

The orbit consists of 7 bones

- Roof: orbital plate of frontal bone, lesser wing of sphenoid bone;

- Ficon orbital plate of maxilla bone, orbital surface of zygomatic bone, orbital process of palatine bone

- Lateral wall: zygomatic bone, greater wing of sphenoid bone

- Medial wall: frontal process of maxillary bone, lacrimal bone, orbital plate of ethmoid bone, body of sphenoid bone

The frontal bone forms the orbital plate and the roof of the orbit. Here, the superior orbital margin contains a supraorbital notch or foramen for the supraorbital neurovascular bundle.

The ethmoid bone gives rise to the inner part of the medial wall, the orbital plate (lamina papyracea).

The lacrimal bone forms the remaining part of the medial wall of the orbit; it articulates: anteriorly with the frontal process of the maxilla; superiorly with the frontal bone; posteriorly with the ethmoid bone; inferiorly with the orbital process of the maxilla.

The sphenoid bone articulates anteriorly with the zygomatic bone, superiorly with the frontal bone, medially with the orbital process of the palatine bone. It forms the optic canal for the optic nerve and ophthalmic artery; the superior orbital fissure, between the lesser and greater wings of the sphenoid bone for the oculomotor, trochlear, and abducens nerves, branches of the ophthalmic division of the trigeminal nerve, superior ophthalmic vein, lymphatics.

Maxillary bone: the frontal process forms part of the medial orbital wall and margin; the orbital process forms the floor of the orbit and contains the infraorbital groove and canal for the infraorbital neurovascular bundle. The infraorbital foramen represents the anterior opening of the infraorbital canal.

The palatine bone orbital process forms a small part of the floor of the orbit posteriorly.

The zygomatic bone forms the greater part of the lateral wall of the orbit and the lateral part of the inferior orbital margin.

II. 2. Extrinsic Eye Muscles

The orbit contains the following muscles: Orbicularis oculi: closes the eyelids, originates in the medial orbital margin and palpebral ligament. Levator palpebrae superioris: elevates the upper eyelid. It is inserted on the apex of the orbit above the optic canal and to the skin and fascia of the upper eyelid and superior tarsal plate. Superior rectus: elevates and adducts the eyeball. It originates from the common tendinous ring at the apex of the orbit and ends on the sclera on the superior surface of the eyeball. Inferior rectus: depresses and adducts the eyeball. It is inserted on the common tendinous ring at the apex of the orbit and the sclera on the inferior surface of the eyeball. Medial rectus: adducts the eyeball. It goes from the common tendinous ring at the apex of the orbit to the sclera on the medial surface of the eyeball. Lateral rectus: adducts the eyeball. It is inserted on the common tendinous ring at the apex of the orbit and the sclera on the lateral surface of the eyeball. Oblique superior depresses and adducts the eyeball. It is inserted on the apex of the orbit above the optic canal, passes through a fibrocartilagenous pulley known as the trochlea and reaches the sclera, on the superior surface of the eyeball. Oblique inferior: elevates and adducts the eyeball. It is inserted on the floor of the orbit lateral to the lacrimal groove and on the sclera on the inferior surface of the eyeball, beneath the lateral rectus muscle.

II. 3.The Eyeball

The eye is the visual system receptor organ. Photoreceptor cells in the retina (rods and cones) transform the Ught signals into electrical signals that are further processed by other retinic neurones: bipolar cells, horizontal cells, amacrine cells, retinal ganglion cells, and interplexiform cells, and transmit the potentials to the optic nerve.

The eye is located in the anterior part of the orbit. It contains two segments: a small transparent anterior seg

ment, the aqueous humor, and a large posterior opaque one, the vitreous body. These are separated by the lens, which is held in place by the suspensor ligaments. The aqueous humor is further divided into anterior and posterior chambers by the iris. The aqueous flows from the posterior chamber, around the iris, and into the anterior chamber, where it drains into the canal of Schlemm. The eyeball is composed of three layers: the outermost (sclera), which continues with the transparent cornea anteriorly; the intermediate (choroid), which continues with the ciliary body and iris anteriorly; and the innermost (retina).

ll.4.The Lacrimal Gland

The lacrimal gland is the organ responsible for tear production (Latin: lacrima = tear). It is located in the orbit beneath the orbital plate of the frontal bone. It is innervated by postganglionic parasympathetic fibers from the pterygopalatine ganglion via communicating branches to the lacrimal nerve. Tears are collected by lacrimal papillae, located medially on the edge of the upper and lower eyelids. They contain two openings called lacrimal puncta that drain the tears into lacrimal canaliculi. The lacrimal sac is located at the medial wall of the orbit, receives lacrimal canaliculi and drains to the nasolacrimal duct.

II. 5. Vessels

The main artery which supplies the eye and orbit is the ophthalmic a. It originates from the internal carotid and courses anteriorly, following the optic nerve on its lateral aspect into the optic canal. After crossing it, the artery gives rise to a lateral branch, the lacrimal artery, directed to the gland and the lateral rectus muscle, and a medial branch, the central retinal artery, the only artery to the retina. Afterwards, the artery curves medially, crossing the nerve on its upper surface and gives rise to its terminal branches:

muscular, anterior and posterior ethmoids, medial palpebral, supraorbital, supratrochlear, dorsal nasal.

There are two ophthalmic veins: superior and inferior, devoid of valves

B Optic Nerve (ll),Visual Pathway and Orbit 127

The superior ophthalmic vein (v. ophthalmica superior) begins at the inner angle of the orbit from the nasofrontal vein which communicates anteriorly with the angular vein; it pursues the same course as the ophthalmic artery, and receives tributaries corresponding to the branches of that vessel. It passes between the two heads of the lateral rectus and through the medial part of the superior orbital fissure, and ends in the cavernous sinus. The inferior ophthalmic vein (v. ophthalmica inferior) begins from a venous network located anteriorly on the floor and medial wall of the orbit; it receives some muscular and lacrimal veins, runs backward into the lower part of the orbit and divides into two branches. One of these passes through the inferior orbital fissure and joins the pterygoid venous plexus, while the other enters the cranium through the superior orbital fissure and ends in the cavernous sinus.

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Optic nerve

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Levator palpebrae superioris muscle

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Olfactory bulb

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Optic nerve


Infraorbital nerve (V2)








Lateral orbital sulcus




Gyrus rectus

A^ I

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Cingulate sulcus

Cingulate gyrus

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^ . Superior oblique muscle




Optic nerve

5 ^ Inferior rectus muscle

Olfactory sulcus








Frontal operculum




Anterior clinoid


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Cingulate sulcus

Cingulate gyrus

Corpus callosum

Lateral ventricle

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^

£ — Corpus callosum, rostrum

- Short insular gyrus

~ Posterior orbital gyrus

^ Medial orbital gyrus

" Olfactory sulcus

" Olfactory tract

^ Gyrus rectus

Optic nerve Sphenoid sinuses



Lateral ventricle

Precentral gyrus


Lateral fissure


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Middle frontal gyrus {F2)

Corpus callosum

— Circular insular sulcus

Subcentral gyrus

Rolandic central operculum

Superior temporal sulcus Short insular gyrus

Middle temporal gyrus (T2) / Uncus (gyrus ambiens)

Inferior temporal gyrus (T3) Paraterminal gyrus (gyrus nuclei)

Internal carotid artery Optic chiasm Subcallosal gyrus

B Optic Nerve (ll),Visual Pathway and Orbit 137








Cornea

Lens

Vitreous body

Inferior oblique muscle

A

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Lateral ventricle

Optic chiasm

Pituitary gland

Sphenoid sinus

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Superior ophthalmic vein

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Sphenoid sinus


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1 4 0 Short Introduction pp. 141-155

Oculomotor (III), Trochlear (IV) and Abducent (VI) Nerves

I. Oculomotor Nerve (III Cranial Nerve)

The nucleus of the oculomotor nerve is on the upper end of the midbrain, ventrally to the sylvian aqueduct, on the median line, in a V-shaped zone formed by the diverging fibers of the medial longitudinal fasciculus.

The complex consists of lateral columns with a general somatic efferent (GSE), which works for the innervation of the eye*s extrinsic muscles (rectus inferior, inferior oblique, rectus medialis, rectus superior), and the nucleus caudalis centralis, which innervates the levator palpebrae superioris muscle. The Westphal nucleus and the anterior median nucleus form the parasympathetic general visceral efferent (GVE) component of the nuclear complex. Their fibers innervate the ciliary muscles and the sphincter pupillae, and travel together with the GSE fibers, remaining located at the periphery of the nerve. For this reason, they are usually the first to be affected by extrinsic compressions (neurovascular conflicts, aneurysms, etc.).

The direct and crossed radicular fibers pass ventrally through the red nucleus and emerge in the interpeduncular fossa, in correspondence with the medial aspect of the cerebral peduncle, immediately below the posterior cerebral and posterior communicating arteries. The nerve enters the cavernous sinus, remaining within its dural lateral wall, in the upper portion, and enters the orbit through the upper lateral aspect of the superior orbital fissure.

Associated with the nuclear complex of the oculomotor nerve, there are three accessory nuclei:

• CajaFs interstitial nucleus: placed on the rostral mesencephalon and formed by neurons mixed with the medial longitudinal fasciculus fibers. The fibers cross at the level of the posterior commissure and head for all the somatic components of the oculomotor nuclear complex, except for the ventral column, the bilaterally trochlear nuclei, the homolateral medial vestibular nucleus, and the spinal cord, as an interstitial spinal tract;

• Darkshevich's nucleus: it is placed in the substantia grisea centralis, in the ventrolateral position and dor-solaterally to the somatic columns of the oculomotor nuclear complex. Its fibers insert into the posterior

commissure but not into the oculomotor nuclear complex.

• Posterior commisure's nucleus: it is placed in the substantia grisea centralis at the dorsolateral level; its cells are strictly connected to the fibers of the posterior commissure.

The nuclear complex of the oculumotor nerve receives impulses from the cerebral cortex, through corticoreticular fibers, from the cerebellum (nucleus dentatus), the nuclei vestibulares (in particular, they reach the lateral somatic cell columns), the colliculus superior (not through a direct connection, but CajaFs nucleus and the mesencephalic reticular formation), the reticular formation, and CajaFs interstitial nucleus.

II. Trochlear Nerve (IV Cranial Nerve)

The trochlear nerve nucleus is on the midbrain's lower position, at the level of the colliculus inferior, ventrolaterally to the sylvian aqueduct. It is considered an appendix of the oculomotor nuclear complex, dorsal and caudal to the medial longitudinal fasciculus.

The GSE fibers move posteriorly and caudally, surround the sylvian aqueduct and penetrate the velum medullaris anterior, or valve of Vieussens, where they cross and emerge on the brainstem's dorsal surface, under the inferior colliculi. They surround the brainstem, penetrate the dural lateral wall of the cavernous sinus below the oculomotor nerve, and enter the orbit through the superior orbital fissure. The IV cranial nerve innervates the superior oblique muscle.

It receives fibers from the medial longitudinal fasciculus, which connects it to the vestibular nuclei.

III. Abducent Nerve (VI Cranial Nerve)

The nucleus of the abducent nerve is located in the pons, near the tegmen of the fourth ventricle, surrounded by the genu of the facial nerves' radicular fibers (colliculus facialis). Its GSE fibers cross the tegmentum rhombencephali moving ventrolaterally, and emerge at the end between pons and medulla, at the level of the pontomedullary sulcus to the foramen cecum's sides, superiorly to the bulbar pyramids. The nerve ascends in the prepontine cistern and penetrates inside the cavernous sinus through the canal of Dorello. It innervates the lateral rectus muscle.

The nucleus of the abducent nerve receives direct and crossed fibers coming from the vestibular nuclei (inferior, medial and lateral) and pulses deriving from the cerebral cortex, through corticoreticular fibers and intercalated neurons in the reticular formation.

Trigeminal Nerve (V Cranial Nerve)

The trigeminal nerve is mixed, mainly sensitive, and containing general somatic afferent (GSA) and motor special visceral efferent (SVE) fibers. It derives from the reunion of three branches: ophthalmic (VI), maxillary (V2) and mandibular (V3). The ophthalmic nerve derives from the conjunction of three main branches: lacrimal, frontal and nasociliary. It carries sensitivity from the upper face and the eye, penetrates the skull through the superior orbital fissure and forms the VI nerve. This passes through the cavernous sinus and reaches Meckel's cave, where the trigeminal ganglion (or Gasser's or semilunar ganglion) is located. The sensitivity of the maxillary region and the upper teeth is carried by the maxillary nerve. It passes through the foramen rotun-dum, enters the cavernous sinus and reaches the Gasserian ganglion. The mixed component is represented by the 3rd branch, the mandibular nerve. It carries sensitivity from the mandibular region of the face and the lower teeth and receives the meningeal branch through the foramen spinosum. Moreover, it carries motor fibers mostly directed to masticator muscles (temporal, masseter and pterygoid) and the tensor veli palatini and tensor timpani muscles. The three branches join together in Gasserian ganglion. This is a plex-iform structure, located in a proper cistern inside Meckel's cave. The preponderance of CSF makes the MR signal of the ganglion CSF-like in T2-w sequences. The GSA component of the trigeminal nerve, with a voluminous root, penetrates the pons' lateral part, at the edge toward the middle cerebellar peduncle, crosses the tegmentum, and ends in the sensory nuclei of the pons and bulb: mesecenphalic nucleus, main sensory nucleus and nucleus spinalis, where a definite topographic organization exists: ophthalmic fibers are more ventral; mandibular dorsal and maxillary ones are intermediate.

The nerve's special visceral efferent (SVE) component originates from the motor nucleus at the level of the pons, and exits medially at the access of the sensory root.

C Oculomotor Nerve (III), Trochlear Nerve (IV), Abducent Nerve (VI) 141

The mesencephalic nucleus of the trigeminal nerve is near the lateral edge of the gray matter of the fourth ventricle's andand sylvian aqueduct's upper parts. Here, proprioceptive impulses (of pressure and kinaesthesia) arrive from teeth, periodontium, hard palate, and capsulae articulares.

The main sensory nucleus is placed laterally at the access of the trigeminal nerve's radicular fibers in the upper part of the pons and receives general somatic afferent (GSA) fibers, transporting impulses for touch and pressure.

The spinal tract extends from the level of the trigeminal nerve's root in the pons to upper cervical spinal segments. It receives impulses from the internal structures of nose and mouth, from the cutaneous facial regions, forehead, cheeks and jawbone, and contains small groups of fibers with GSA components coming from the VII, IX and X nerves.

The motor nucleus (masticator nucleus) is placed medially between the motor root and the main sensory nucleus. It receives collaterals from the mesencephalic and main sensory nuclei and from the nucleus of the VIII nerve.

The sensory nuclei of the trigeminal nerve (principal and spinal) show connections to the reticular formation of the bulb, to the cerebellum (through the inferior cerebral peduncle), and to the nucleus ventralis posteromedialis thalami of the opposite side (ventral thalamic trigeminal tract) and of the same side (dorsal trigeminal tract).

The mesencephalic nucleus projects to the cerebellum. It is also connected to the nuclei of XII, XI, X, IX, VII and V nerves for corneal, lacrimal, sneezing, vomiting, salivary and oculocardiac reflexes.

Accessory oculomotor

nucleus

Oculomotor nucleus

Trochlear nucleus

Abducent nucleus


III Cranial Nerve: Oculomotor Nerve

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VI cranial nerve, cavernous portion

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C Oculomotor Nerve (III), Trochlear Nerve (IV), Abducent Nerve (VI) 1 4 3

IV Cranial Nerve: Trochlear Nerve

T

1 4 4 4 Cranial Nerves and Related Systems

VI Cranial Nerve: Abducent Nerve

Emergence at the pontomedullary sulcus Cisternal portion at the mid-level of the pons

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* Entry into the cavernous sinus ^ ^^M through Dorello's canal

Cisternal portion

C Oculomotor Nerve (III), Trochlear Nerve (IV), Abducent Nerve (VI) 145

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IV cranial nerve ^

V cranial nerve ^

VII! cranial nerve (cochlear) ^

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Posterior communicating artery



Superior cerebellar artery

V cranial nerve at the trigeminal porus (piercing the dura of the petrous apex)

Antero-inferior cerebellar artery

ill cranial nerve

Entry of the V cranial nerve into Meckel's cave

III cranial nerve

VI cranial nerve


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VI cranial nerve (ophthalmic division)

V2 cranial nerve (maxillary division) V3 cranial nerve (mandibular division) through the foramen ovale

V3 cranial nerve (mandibular division)

Posterior VI cranial communicating artery nerve

II cranial nerve




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Ophthalmic Abducent Trochlear Oculomotor nerve (VI) nerve nerve nerve


Spinal tract of trigeminal nerve

Spinal nucleus of trigeminal nerve

Sensory nucleus of trigeminal nerve

Sensory root of trigeminal nerve

Mesencephalic nucleus of trigeminal nerve

Mesencephalic tract of trigeminal nerve

Motor nucleus of trigeminal nerve


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Maxillary nerve (V2), branch of trigeminal nerve

Mandibular nerve (V3), branch of trigeminal nerve

Branches from cervical plexus

Dorsal rami of cervical spinal nerves

Auricular branches of vagus nerve



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Maxillary nerve (V2)

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Mandibular nerve (foramen ovale)

Mandibular nerve {V2) -'

Middle nneningeal artery

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Facial (VII Cranial Nerve), Cochlear (VIII Cranial Nerve, pars Cochlearis), Vestibular (VIII Cranial Nerve, pars Vestibularis) Nerves, Related Systems and Petrous Bone

I. Facial Nerve (VII Cranial Nerve) and Its System

The motor nucleus of the facial nerve is placed in the tegmen of the pons, dorsally to the nucleus olivaris superior and ven-tromedially to the nucleus spinalis of the trigeminal nerve. The special visceral efferent (SVE) fibers emerging from the dorsal side of the nucleus are dorsomedially projected on the tegmen of the fourth ventricle. These fibers go up longitudinally, medially to the nucleus of the abducent nerve, and dor-sally to the medial longitudinal fasciculus; near the rostral pole of the abducent's nucleus, they curve ventrolaterally and emerge from the brainstem into the bulbopontine sulcus, in correspondence with the supraolivary fossa, and medially to the nervus intermedins. They innervate the facial mimetic muscles, the posterior belly of digastric muscle, the stylohy-oideus, styloglossus, platysma, buccinator, stapedius muscles, and some muscles of the velum palati.

This nucleus exhibits connections with the sensory nuclei of the V, VIII (cochlear), IX and X cc.nn.

The general somatic afferent (GSA) fibers carry cutaneous sensory impulses from the external auditory meatus and the region behind the ear; centrally, these fibers enter the dorsal portion of the spinal tract of the trigeminal nerve.

The preganglionic parasympathetic general visceral efferent (GVE) radicular component of the nervus intermedins, or Wrisberg's nerve, originates from two nuclei, the lacrimo-muconasal nucleus and the superior salivatory nucleus, located in the pons, rostrally to the inferior salivatory nucleus, and emerges from the bulbopontine sulcus, between the motor root of the facial nerve and the vestibular nerve.

The bundle of fibers originating from the lacrimo-mu-conasal nucleus emerges in the bulbopontine sulcus with the motor root of the facial nerve, and innervates the lacrimal gland, the nasal and buccal mucosa. The small radicular component originating from the superior salivatory nucleus spreads to the submandibular and sublingual glands.

These two nuclei are connected with the gustatory nucleus (VII, IX, and X cc.nn.) and the main sensory nucleus of the trigeminal nerve.

The special visceral afferent fibers (SVA) of the nervus intermedins reach the rostral portion of the nucleus of the trac-tus solitarius (gustatory nucleus), and carry the gustatory sensitivity of the front two-thirds of the tongue, whereas the general somatic afferent (GSA) fibers belong to the dorsal part of the spinal tract of the trigeminal nerve and carry cutaneous sensory impulses from the external auditory meatus and the region behind the ear.

The nerve crosses the ponto-cerebellar angle's cistern together with the VIII cranial nerve, enters the internal acoustic canal and penetrates its bottom. This is separated by a horizontal bony lamina (crista falciformis) into two compartments. The superior one is divided in two by a vertical fibrous wall. The complex facial-Wrisberg's intermediate nerve penetrates the upper-anterior compartment, and reaches the geniculate fovea in the petrous bone, where the geniculate ganglion is located. Here, fibers of the intermediate nerve separate and course anteriorly into the greater petrosal superficial nerve, toward the pterygopalatine ganglion and the lacrimal gland. The remaining fibers of the facial nerve curve backward and remain horizontal, then go downward reaching the foramen stylomastoideum, where they exit to join the parotid gland. Two main branches originate during this course: nervi stapedium and chorda tympani.

II. Cochlear Nerve, Vestibular Nerve (VIII Cranial Nerves) and Their Systems

II. 1. Acoustic System

Acoustic stimuli are generated by the tympanic membrane and are transmitted to the manubrium of the malleus, then to the incus and the stapes. The stapes base articulates with the oval window, which transmits the acoustic wave to the perilympha of the cochlea. The cochlea is a spiral structure composed of two and a half turns around a central bony structure, the modiolus. Each cochlear turn is divided by an osseous spiral lamina and a membranous one (basilar membrane), which contains the endolymphatic receptor system. Fibers originate from the basilar membrane, reach the spiral (Corti's) ganglion and cross the cribriform infero-anterior part of the internal wall of the internal acoustic canal (iac). Here, they form the cochlear nerve that joins the superior and inferior vestibular nerves and the posterior ampullary nerve, forming the VIII cranial nerve, and traveling together

with the facial one through the ponto-cerebellar cistern. The cochlear component of the vestibulocochlear nerve reaches the ventral and dorsal cochlear nuclei on the lateral side of the inferior cerebellar peduncle in the bulbopontine area, entering the brainstem at the supraolivary fossa level and branching off. These nuclei present a tonotopic localization which is also maintained in the following tracts of the pathway: the fibers coming from the apical turn of the cochlea, where low-pitched tones are located, reach the nucleus cochlearis ventralis and the ventral part of the dorsal nucleus; the fibers coming from the basal turn of the cochlea, where high-pitched tones are located, terminate in the dorsal portion of the dorsal nucleus.

The cochlear nuclei form the central cochlear pathway that is made up of acoustic striae of ventral type (originated from the ventral nucleus), of dorsal type (originated from the dorsal nucleus) and of intermediate type (originated from the dorsal portion of the ventral nucleus). These provide fibers to the reticular formation and the nucleus olivaris superior of the corpus trapezoideum, of the lateral lemniscus and to the superior quadrigeminal body. They go on to cross the median raphe and, like the lateral lemniscus, reach the medial geniculate bodies and the telencephalic cortex (gyrus temporalis superior).

The motor nucleus of the V, VI and VII cc.nn. exhibits connections with these nuclei that are inserted along the central acoustic pathway.

II. 2. Vestibular System The vestibular stimuli come from fibers collected together in three main branches: inferior and superior vestibular nerves and posterior ampullary nerve. The superior vestibular nerve receives fibers coming from utricle, and superior and lateral semicircular canals; the inferior vestibular nerve is formed by fibers from the saccule; fibers of the posterior semicircular canal are collected in the posterior ampullary nerve. The superior vestibular nerve crosses the posterior wall of the iac in the postero-superior space, while the pos-tero-inferior is occupied by inferior vestibular and posterior ampullary nerves. After crossing the iac's posterior wall, the three nerves form Scarpa's ganglion. From this point on, the vestibular nerve joins the acoustic and fuses with it. Vestibular nuclei are located on the tegmen of the fourth ventricle, rostrally to the hypoglossal nucleus, and extend well beyond

E Facial Nerve (VII) and Vestibulo-Cochlear Nerve (VIII), Acoustic and Vestibular Systems, Petrous Pyramid -1 157

the nucleus of the abducent nerve. They are reached by the fibers of the vestibular nerve which enter the brainstem in correspondence with the retroolivary fossa, at the bulbopon-tine sulcus level. Once they have entered the vestibular complex, they branch off and spread in various ways to the nuclei of the same and opposite side, and to the interstitial nucleus of the vestibular nerve which is located between the vestibular fibers near the point where the nerve enters the brainstem, and then move towards the cerebellar cortex (nodule, uvula and flocculus of the same side). They carry the stimuli of gravity and acceleration.

The nuclei are placed in two longitudinal columns: the lateral column includes the descending (Deiters' nucleus), lateral and superior vestibular nuclei; the medial column is made up of the medial vestibular nucleus.

The descending vestibular nucleus is located in the bulb medially to the accessory cuneate nucleus. It then spreads rostrally inside the inferior cerebellar peduncle as far as the site where the vestibular nerve enters the brainstem. Distinctive projections from the macula utriculi and the macula sac-culi (dorsolateral portion of the descending vestibular nucleus) reach this point.

The vestibular nuclei present connections with the cortex (ascending frontal gyrus), the bone marrow (vestibular-spinal and spinal-vestibular tracts), the cerebellum (vestibulocerebellar and cerebellovestibular tracts), the reticular formation, the nuclei of the III, IV, VI, and XI cc.nn. through the medial longitudinal fasciculus, and with the motor nucleus of the V c.n.

Vestibular nuclei

Cochlear nuclei

Facial nerve (internal genu)

Facial nucleus

Salivatory nucleus


^

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Cochlear nerve

Vestibular nerve

Facial nerve

/ Facial nerve

Vestibulocochlear nerve •

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E Facial Nerve (VII) and Vestlbulo-Cochlear Nerve (VIII), Acoustic and Vestibular Systems, Petrous Pyramid - 159

^ MOTOR FIBERS

^ GLAND SECRETORY FIBERS

# TASTE

# SENSORY FIBERS

INTERNAL ACOUSTIC CANAL

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POSTERIOR AURICULAR" NERVE

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Facial nerve (VII), petrous segment

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C.n. VII, intracanalicular segment

C.n.VII, cisternal segment

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E Facial Nerve (Vlt) and Vestibulo-Cochlear Nerve (VIII), Acoustic and Vestibular Systems, Petrous Pyramid -1 161

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Inferior vestibular nerve

Superior vestibular nerve

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Inferior vestibular nerve


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Superior vestibular nerve

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E Facial Nerve (VII) and Vestibulocochlear Nerve (VIII), Acoustic and Vestibular Systems, Petrous Pyramid -1 163

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Inferior cerebellar peduncle

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Dorsal cochlear nucleus

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Transverse gyrus of HeschI and planum temporale

Acoustic radiation

Medial geniculate body

Brachium conjunctivum (superior cerebellar peduncle)

Superior lateral olivary nucleus

Trapezoid body

Nucleus of trapezoid body

Superior medial olivary nucleus

E Facial Nerve (VII) and Vestibulocochlear Nerve (VIII), Acoustic and Vestibular Systems, Petrous Pyramid -1 1 6 5

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Vestibular System

Interstitial nucleus

Oculomotor nucleus

Trochlear nucleus

Superior vestibular nucleus

Inferior vestibular nucleus

Vestibular nerve

Medial vestibular nucleus

Medial longitudinal fasciculus

Vestibular cortical area

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Posteroinferior and posterolateral ventral nuclei of thalamus

Lateral vestibular nucleus (of Deiters)

Lateral vestibulospinal tract

Medial vestibulospinal tract


Lateral vestibulospinal tract

Medial vestibulospinal tract

Vestibular nerve

Lateral vestibular nucleus (Deiters)

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E Facial Nerve (VII) and Vestibulocochlear Nerve (VIII), Acoustic and Vestibular Systems, Petrous Pyramid - II: Computed Tomography 171

CT Coronal Section

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Superior semicircular canal

Superior ampulla

Vestibule

Common crus

Inner Ear 4 I Labyrinth

Internal auditory canal (lAC)

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Mastoid air cells

Tympanic cavity

Ossicular chain


Lateral semicircular

Oval window canal

Basilar turn of cochlea Bony labirinth: 3D CT reconstruction

Short crus of incus

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Body of incus

Long crus of incus T

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CT Coronal Section

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Axial Sections

Carotid canal (vertical portion)

Tynripanic membrane

External auditory canal

Tympanic cavity (hypotympanum)

^ Septum jugulohypotympanicum

III segment (vertical, mastoid) of facial canal

Mastoid air cells

Sigmoid sinus

Jugular spina Jugular fossa


'jfi. Foramen ovale

Foramen spinosum

Auditory (eustachian) tube

Head of condylar process of mandible

Carotid canal


Manubrium of malleus

segment (vertical, mastoid) of facial canal

Cochlear aqueduct

Mastoid air cells

'\^^^'

'^^- } c

> "

E Facial Nerve (VII) and Vestibulo-Cochlear Nerve (VIII), Acoustic and Vestibular Systems, Petrous Pyramid - II: Computed Tomography 175

N ^ - - 4

Carotid canal (horizontal portion)

Glenoid fossa of the tennporonnandibular joint


Tympanic cavity

Manubrium of malleus


Long crus of incus

Basal turn of cochlea

Round window


Cochlear aqueduct


Carotid canal (horizontal portion)

-«^S

T— Posterior ampulla

Posterior semicircular Sinus canal tympani


Malleus

Long crus of incus

Incudostapedial joint

Canal of the stapedial muscle


Pyramidal eminence

Nf)

T* ^ ^ - — s ^ "

. ^ • j '

X ,>ir

^ ^

i • i


Carotid canal

Tensor tympani muscle in the bony canal

Apical turn

Middle turn

Basal turn

y Cochlea


^^ Vestibule

/ Posterior semicircular

canal

External opening of vestibular aqueduct for the endolymphatic duct

- ^ .

^.^.-.'e ^^^ ' ^m

^ * ' : %

\l


**. ^

Canal of tensor tympani / muscle

Cochlea

Head of nnalleus

Body of incus

— Short crus of incus

Superior ampulla

Aditusad antrum

Vestibule

Lateral semicircular canal


^^,<

^^ s^j^

,>'"' ' „,.„>' '4r


\ . ^

V

•I

•• ^ H • X \ ^ V

•l^...*^

Groove of greater petrosal nerve

Modiolus

II segment (horizontal, tynnpanic) of facial canal

^ Head of malleus

- Incudo-malleolarjoint

- Body of incus

Aditus ad antrum

Vestibulus

Antrum



Internal auditory canal

Vestibular aqueduct

.v

!c:

im^m


\ ^^--'3^ \ Groove of greater petrosal nerve

_ Spiral lamina of the cochlea

^ Geniculate fossa

Vestibulus

Antrum




Vestibular aqueduct


f A - J*l^

^

^' ^ S^ ^^


_ , — Geniculate fossa

_ I segment (horizontal, labyrinthine) of facial nerve

Cochlea


nternal auditory canal

External opening for the endolymphatic duct


i t '*•-.

• # . '

%

.i . i ^ Middle cranial fossa

j ^ , - ^ ^ 5 ^ ^ ~ Superior semicircular canal

Mastoid


^ .% I

1 ^ Superior semicircular canal

Posterior cranial fossa

i

^ .HP-'^!^»< %»

%

X

1 ^

E Facial Nerve (VII) and Vestibulo-Cochlear Nerve (VIII), Acoustic and Vestibular Systems, Petrous Pyramid - II: Computed Tomography 1 8 3


*

'I

1L

f0^ ' p

? I 1


Coronal Sections

Internal carotid artery ^ in carotid canal

Canal of tensor tynnpani muscle

Glenoid cavity of temporal bone

Condylar process of mandible

Temporomandibular joint



Internal carotid artery in carotid canal

; v ^

• *t


Canal of tensor tympani muscle

Hypotympanum

* t M * * . * ' m %

if ^ - < ^ ^ / ^


Middle turn ] > Cochlea

Upper turn J

Geniculum of facial nerve

Tensor tynnpani muscle

f* •••• HmmTt' <* ^ — — - ^ ^ - - Head of malleus ^ ' ^ H K / F " * W ^ ^ » ^

- Septum jugulohypotympanicum ^ • * ' . w ' ^ ^

^ - # ^

E Facial Nerve (VII) and Vestlbulo-Cochlear Nerve (VIII), Acoustic and Vestibular Systems, Petrous Pyramid - II: Computed Tomography 187

Cochlea

Modiolus

Tendon of tensor tynnpani muscle

Body of incus

Malleus

Tympanic membrane

Septum jugulohypotympanicum •

Jugular bulb A ^' ^


Cochlea

I portion (horizontal) of facial nerve

Tendon of tensor tympani muscle

Body of incus

Malleus

— Scutum

Tympanic membrane

Septum jugulohypotympanicum

':t^^.

.< 'i» /

^,yt*^-^v-.„.^ J

Jugular bulb


/ Cochlea

Facial canal

y Tegmen tympani

Head of malleus

— Manubrium of malleus


Tympanic membrane

Septum jugulohypotympanicum

Jugular bulb


Crista falciformis


II segment (horizontal, tympanic) of facial canal

,^_^ Head of malleus

i^ ^^^^^ Scutum

^k^^

^T*

; f i f , K ^ %

~- Stapes

^ External auditory canal

^ Cochlea

^ Septum jugulohypotympanicum

^''P\m> V V

2 ^ ' ' | » s ^ Jugular bulb


Crista falciformis


'in

A>-7i '

M'

^

-m *


Vestibule

Scutum

Stapes

Promontory

•^ t •-^K

^ ^





m^\

#u J

^ f . .

Antrum


Vestibule

Short crus of incus

*»^> < ' _ ^

:ir-*


Oval window

Stapes

Promontory


» * ^

% MT <r^_

#

• y ^/t:

§5



Antrum

y^ Korner's septum


Vestibule



<'r

-*1




Superior vestibular canal

Utriculus

Antrum _

Lateral semicircular canal ^ ^ V i l i ^ w H ^ ^ ' I


Sinus tympani


Subiculum

/ X

I

Round window


.m^ A ^

9 ^ ...m^ ^

r/^ • - Inferior vestibular canal

Vestibular aqueduct

Styloid process

m /Ow "' -'-r


^ Superior semicircular canal

/ Superior ampulla

^ Lateral semicircular canal

* ^ Posterior ampulla

I segment (vertical, mastoid)

* ^ ^ k W% •^•^_ . ..^JJt - Styloid process . - ^ l i * ^ ^ ^

I 1/ ' ^ Mastoid

|C ' c ' ^ Stylomastoid foramen ^ i w ^

r


- ^

^i A

• • ^

III segment (vertical, mastoid) of facial canal

Mastoid

Stylomastoid foramen

Sigmoid sinus

Condylar canal

Occipital condyle

Lateral mass of atlas ii> f P

.^^/


Glossopharyngeal (IX Cranial Nerve), Vagus (X Cranial Nerve), Accessory (XI Cranial Nerve), Hypoglossal (XII Cranial Nerve) Nerves

The ninth (glossopharyngeal) and tenth (vagus) nerves arise from the upper part of the medulla, lateral to the olive. The eleventh (accessory) emerges behind or lateral to the olive, with several fibers extended along most of the medulla length. The twelfth (hypoglossal) nerve emerges from the anterolateral (preolivary) sulcus at the lower part of the medulla.

The IX, X and XI cranial nerves reach the pars nervosa of the jugular foramen, while the XII cranial nerve exits the skull through the hypoglossal canal.

I. Glossopharyngeal Nerve (IX Cranial Nerve)

At the bulbar level, the glossopharyngeal nerve comes from a group of cells located in the rostral portion of the nucleus ambiguus. This originates a small bundle of special visceral efferent (SVE) fibers which emerges cranially to the fibers of the X c.n., at the level of the posterior lateral sulcus of the bulb (sulcus of mixed nerves), and innervates the stylopha-ryngeus and the cephalopharyngeus muscles.

The inferior salivatory nucleus (cranial part of the dorsal motor nucleus) originates the preganglionic general visceral efferent (GVE) fibers, which immediately emerge in the sulcus of mixed nerves above the roots of the vagus and innervate the parotid gland. The inferior salivatory nucleus is reached by fibers from the hypothalamus which present numerous connections with the neurons of the reticular formation. Moreover, fibers from the nucleus of the tractus solitar-ius (VII, IX and X cc.nn.) and from the main sensory nucleus of the trigeminal nerve reach this point.

The spinal tract and the spinal nucleus of the trigeminal nerve are reached by a small contingent of GSA fibers carrying general somatic sensitivity from cutaneous areas around the ear.

The special visceral afferent (SVA) fibers carrying gustatory sensations from the posterior third part of the tongue enter the posterolateral part of the bulb, in the sulcus of mixed nerves, together with the roots of the vagus, and spread to the rostral portions of the bulbar component of the nucleus of the tractus solitarius (gustatory nucleus).

The general visceral afferent (GVA) fibers that carry impulses regarding the sense of touch, the thermal sense and pain from the mucous membranes of the posterior third of the tongue, the tonsils, the back wall of the upper pharynx and the eustachian tube, terminate in the caudal portion of the nucleus of the tractus solitarius, together with the GVA component of the X c.n.

The GVA fibers carrying impulses from the carotid sinus (carotid sinus reflex) belong to the dorsal motor nucleus of the vagus.

II. Vagus Nerve (X Cranial Nerve)

The ambiguous nucleus is located in the reticular formation at the bulbar level. The SVE fibers move diagonally in a dor-somedial direction like an arch, and join the preganglionic general visceral efferent fibers coming from the dorsal motor nucleus of the vagus to eventually emerge caudally to those of the glossopharyngeal nerve, at the level of the posterior lateral sulcus (sulcus of mixed nerves).

The rostral portion of this nucleus gives origin to the special visceral efferent fibers of the IX c.n., whereas the caudal portion is represented by the cranial part of the spinal accessory nerve and originates the special visceral efferent fibers of the XI c.n. which, joining the fibers of the X c.n., innervate the pharynx and larynx muscles.

The ambiguous nucleus receives rami from the visceral afferent nuclei of the vagus itself, from the IX c.n. and the main sensory nucleus of the V c.n.

The dorsal motor nucleus of the vagus is located in the bulb, posterolaterally to the hypoglossal nucleus, at the level of the ala cinerea in the tegmen of the fourth ventricle.

Preganglionic GVE fibers, originating from the most caudal portion of the nucleus, cross the spinal tract and the spinal nucleus of the trigeminal nerve, emerge in correspondence with the mixed nerves, and spread to the heart (SA, AV nodes, striated muscle in the carotid sinus reflex), the respiratory tract and abdominal viscera.

The dorsal motor nucleus receives fibers mainly from the hypothalamus, from the nucleus of the tractus solitarius and the main sensory nucleus of the V c.n.

The nucleus of the tractus solitarius receives the vagal afferent fibers which enter the inferior cerebellar peduncle ventrally near the lateral side of the bulb, crossing the spinal

tract and the spinal nucleus of the trigenimal nerve. A small contingent of GSA fibers coming from the cutaneous

areas behind the ear and the external auditory meatus enters the dorsal portion of the spinal tract of the trigeminal nerve.

A larger group of general and specific afferent fibers moves dorsomedially and enters the solitary fasciculus together with the fibers of the glossopharyngeal nerve and the nervus intermedins.

The special visceral afferent fibers of the glossopharyngeal nerve and nervus intermedins and the vagus coming from the gustatory buds in the epiglottis region terminate in the rostral part of the nucleus of the tractus solitarius (gustatory nucleus).

III. Accessory Nerve (XI Cranial Nerve)

The SVE component of the spinal accessory nerve originates from a group of bulbar cells, placed ventrally to the nucleus of the IX c.n. This is the cranial or supraspinal component of the spinal accessory nerve and corresponds to the most caudal portion of the nucleus ambiguus.

The fibers emerge from the lateral surface of the bulb, caudally to the vagal filaments, innervating the intrinsic tongue muscles together with those of the nervus laryngeus inferior (recurrent).

The spinal part of the GSE accessory nerve originates from a cell column located in the anterior horn of the first five or six cervical segments in the lateral position. The radicular fibers originating from these cells curve posterolaterally and emerge from the lateral side of the cervical cord between the dorsal and ventral roots of the spinal nerves. They innervate the sternocleidomastoid muscle of the same side and the upper portions of the trapezius.

The spinal component of the accessory nerve receives fibers through the medial longitudinal fasciculus for the coordination of head and eye rotation movements (cephalo-and oculogyric movements).

IV. Hypoglossal Nerve (XII Cranial Nerve)

The nucleus of the hypoglossal nerve is located in the dorsal region of the medulla, from the lower edge up to half the tegmen of the fourth ventricle.

F Glossopharyngeal Nerve (IX), Vagus Nerve (X), Accessory Nerve (XI), Hypoglossal Nerve (XII) 199

The general somatic efferent (GSE) roots emerge from the nucleus ventrally, move forward and outside, and along the lateral margin of the medial longitudinal fasciculus and the medial lemniscus and cross the medial parts of the inferior olive complex. They eventually exit at the level of the anterolateral sulcus of the bulb (preolivary sulcus), between the pyramid and the bulbar olive.

They innervate the intrinsic tongue muscles, the genioglossus, hyoglossus and styloglossus muscles.

The nucleus of the hypoglossal nerve receives collaterals from the descending root of the trigeminal nerve.

Hypoglossal nucleus

Dorsal nucleus of vagus nerve

Spinal nucleus of accessory nerve

Salivatory nucleus

Ambiguous nucleus

Glossopharyngeal nucleus


Pyramis

Olive

IX, X, XI cc.nn.

Fossetta lateralis

Foramen of Luschka

Foramen of Magendie

' ^ / ^

\ .<

> '

/ .

/

V . ^

Jugular Foramen

Accessory nerve

Vagus nerve

Glossopharyngeal nerve

, f

I

Glossopharyngeal Nerve (IX), Vagus Nerve (X), Accessory Nerve (XI), Hypoglossal Nerve (XII) 201

\^\^ Um^

V

\^ Hypoglossal nerve (XII c.n.) and hypoglossal canal

Hypoglossal Canal

\

^ )

4 a

>

1

4

)


VII and VIII cranial nerves

Glossopharyngeal, vagus and accessory nen^es —

* ;^

- f

j

Hypoglossal nerve — I

} f^"\ i

Accessory nerve

First cervical roots

5 Functional Systems

2 0 4 Short Introduction pp. 205-215

Functional Systems

In this chapter, some of the main CNS structures are grouped together with particular respect to their functional activity. The classification is somewhat arbitrary and covers only a practical aspect: to allow easy identification of a possible lesion location based on symptoms and signs. The main systems are considered on the following pages, while other systems are dealt with together with their cranial nerves. Several other complex cerebral functions not routinely visible through neuroradiological studies are not considered in this chapter.

are located in the genu, while in the spinal cord the more distal fibers are the more peripheral. The main terminations of the corticofugal system are: thalamus, striatum, brainstem and spinal cord. In the brainstem, the most important terminations are the tectum, the basal pontine nuclei, and the reticular formation; in the spinal cord, fibers terminate in the anterior horn, in correspondence with the motor nuclei.

Motor Systems: I

Pyramidal (Primary) Motor System

The motor function is mainly supported by the corticospinal (or pyramidal) tract. The majority of fibers of the pyramidal tract take origin from the precentral gyrus (primary motor area - area 4), and caudal premotor cortex (area 6). The largest amount comes from the axons of the giant pyramidal (or Betz's) neurons located in the V and VI layers of the posterior fifth of the motor cortex. The motor cortex is somatotopically organized, and movements of the hind limb are located in the medial motor cortex (lobulus paracen-tralis, with the foot located caudally, and the hip at the vertex). The trunk is in the upper part of the prerolandic gyrus, followed by the forelimb and the hand. The motor area for the contralateral hand is thicker than the rest of the primary motor cortex and folded; therefore it is well recognizable ("omega" or "epsilon" sign). Movements of the face are located successively, closer to the sylvian fissure. During their course, the axons pass through the centrum semiovale, the corona radiata, the genu and posterior limb of the internal capsule, the cerebral peduncle, the pons and the medulla. Here, approximately at the foramen magnum level, 80-90% of fibers cross the midline (pyramidal decussation) continuing their course in the anterolateral spinal column (tractus pyramidalis lateralis). The remaining fibers, whose role is still controversial, remain homolateral (tractus pyramidalis anterior). The fibers are somatotopically organized in their entire course: in the internal capsule, head and neck fibers

A Motor Systems -1: Pyramidal System 205

Motor Systems - (I) Pyramidal System

Postcentral gyrus (area 2,1,3) ^ ^

Central sulcus

>i. Parietopontine tract — , iSS

Occipitopontme tract— s s^—=-

Temporopontine tract

" - '"^:^ "" # ' " " " ^ ' ' ^ ' ' ^ ^ Pyramidal trac

Motor cortex (area 4)

— Premotor cortex (area 6)

Premotor cortex (area 8)

Pyramidal tract

Frontopontine tract

• : i •"

I Pyramidal decussation

' /

206 5 Functional Systems

'f

r s ^ . J ^

^ >

A ..Irf

Corticospinal tract

\

„„ . J ^ A


r

L

F %'

Corticospinal tract

A

44

«.,

L

'"^m

^ f

J


-^

# / /

V

L

Corticospinal tract, posterior limb of the internal capsule

0

/A Corticospinal tract,

corona radiata

Primary motor cortex (area 4)

Areas 2,1,3

PremotorareaS

] Premotorarea6

Superior frontal gyrus (F1) Middle frontal gyrus (F2)

Precentral gyrus

Postcentral gyrus

A Motor Systems -1: Pyramidal System 2 0 9


Areas 2,1,3

i i * . ^ l . Premotor area 8

I Premotor area 6



Precentral gyrus

Postcentral gyrus



Precentral gyrus (Fa, ascending frontal gyrus)

Postcentral gyrus (Pa, ascending parietal gyrus)

2 1 0 5 Functional Systems


Areas 2,1,3

:;:f ••#1'": Premotor area 8

I Premotor area 6

^ Superior f frontal gyrus (Fl)


Precentral gyrus

I— Postcentral gyrus r I

/

.^^

"-:€%

,..•.."•^•

\ Superior y frontal gyrus (Fl)

I Middle y frontal gyrus (F2)

Precentral gyrus

Postcentral gyrus

Paracentral lobule

Hand motor area: middle genu of precentral gyrus (preCG) (deep portion)


^-£ vi i'^

1 "Epsilon" sign

^

rf «*

t * # # ^ - -•"

\ ^

* C

1

V

"Omega" sign "Hook" sign


Region of activation obtained during a right finger tapping task.The hand motor area: middle genu of precentral gyrus (preCC). Courtesy of Massimo Caulo, MD, PhD, ITAB, Chieti, Italy

A Motor Systems - 1 : Pyramidal System 213

Va^^

V

Region of activation obtained during right toe flexion task. Courtesy of Massimo Caulo, MD, PhD, ITAB, Chieti, Italy


Scheme: Sensory and Motor Pathways

TTD = Touch temperature pain sensibility

PE = Propioceptive and epicritic sensibility

\

Centrum semiovale -Corona radiata -r

Capsula interna

^

TiMCiU . p

? #• •ici iviTitotv- LI I on

1st sensory neuron

% / ^ . Ny Sensory

ganglion

1

Lemniscus medialis

A Motor Systems - 1 : Pyramidal System 215

Anterior

Prothopatic c I05|||a;^ Pain-Temp.,

- sensibV /

Somatotopic distribution of intramedullary fibers tm

ant^onist

muscle

afferent spin die

Golgi tendon

(pyramidal) Inhibitory interneuron


Motor Systems: II

Extrapyramidal Motor System And Thalamus

The definition "extrapyramidal system" dates back to the first decades of the last century, when two main, independent motor systems were defined: the pyramidal and the other one, called extrapyramidal. However, this definition has become inadequate by now, and no longer represents the complexity of motor system regulation. Yet, the term extrapyramidal is still used to define motor neurons and pathways relating to the basal ganglia. The basal ganglia comprise the caudate nucleus, the putamen, the globus pallidus, the claus-trum, the nucleus accumbens, the subtalamic nucleus, the substantia nigra, the red nucleus, and the periaqueductal gray matter. Other smaller nuclei are also attributed to the extrapyramidal system. The ventral basal thalamus is also considered part of the extrapyramidal system. Because of limits due to imaging cuts, illustrations in this chapter also include thalamic nuclei. Therefore, thalamic anatomy has been improperly included, and will be briefly discussed in the following pages.

I. Basal Ganglia

The striatum is made up of caudate nucleus and putamen. Its volume is approximately 10 cc. The caudate nucleus and the putamen are connected to each other anteriorly, where the head of the former continues with the latter. Posteriorly, they are separated by the anterior limb of the internal capsule, while the posterior limb separates the putamen from the thalamus. The pallidus lies medially to the putamen. Putamen plus pallidus form the lentiform nucleus. The globus pallidus can be divided into an external and an internal segment, separated by the medial medullary lamina. The claustrum is a thin lamina of gray matter lying between the insular cortex and the striatum, separated from the former by the extreme capsule, and from the latter by the external capsule. The nucleus accumbens lies adjacent to the rostromedial part of the striatum. The subthalamic nucleus is situated in the most caudal part of the diencephalon, dorsomedial to the posterior limb of the internal capsule, overlying the rostral part of the substantia nigra. The substantia nigra is the largest cell mass of the mesencephalon. It separates the tegmentum from the cerebral

peduncle. It is divided into a dorsal cellular portion (pars com-pacta) and a ventral, less cellular pars (pars reticulata). The pars compacta synthesizes Dopamine.

II. Main Extrapyramidal Circuits

The following paragraph briefly describes the main circuits involved in several pathological processes.

• The principal striatal circuit: cortex - striatum - pallidus - thalamus - cortex. The whole of neocortex sends fibers to caudates and put-amina. However, most cortical areas project only on the ipsilateral striatum, while the premotor (6,8), motor (4) and somatosensory (3,1,2) cortex distributes fibers bilaterally. Particular meaning is nowadays given to the supplementary motor area, considered an active part of the extrapyramidal system. This belongs to the supplementary motor area (area 6) and is located on the medial aspect of the superior frontal gyrus, in front of the paracentral lobule.

• The first accessory striatal circuit: striatum - pallidus -thalamus - striatum These fibers form the striopallidal and pallidal efferent circuit, which involves the fasciculus thalamicus and terminates in the centromedian and parafascicular nuclei of the thalamus.

• The second accessory striatal circuit: pallidus - nucleus subthalamicum - pallidus The pallidosubthalamic and the subthalamopallidal projections are GABA mediated and involved in several pathological and pathophysiological conditions. The lesion of these can be responsible for ballism in normal subjects, and seems to inhibit parkinsonian symptoms in affected subjects.

• The third accessory striatal circuit: striatum - substantia nigra - striatum The striato-nigral fibers terminate mostly, but not exclusively, in the reticular part of the S.N., and contain large numbers of GABA-, substance P- and dynorphin-positive fibers. The ascending fibers (nigrostriatal system) originate mostly from the dopaminergic cells of the pars compacta of the S.N. These fibers also have a presynaptic glu-tamatergic connection.

The fourth accessory striatal circuit: cortex - striatum substantia nigra - thalamus - cortex

III. Thalamus

The thalamus is a gray cell mass about 4 cm long, lying on each side of the third ventricle, fused together with the contralateral through a thin junction, the interthalamic mass. The thalamus reaches the third ventricle caudally below and the foramen of Monro anteriorly. The posterior part is broader (pulvinar) and overhangs the quadrigeminal plate. Below the thalamus is the lateral geniculate body; infero-me-dially the medial geniculate body is separated from it by the brachium of the superior colliculus. Below the thalamus laterally is the subthalamic nucleus, and medially the red nucleus. Superiorly, the thalamus is covered by a layer of white matter and separated from the caudate nucleus by the stria terminalis and the thalamostriate vein. The lateral aspect of the superior surface forms part of the floor of the lateral ventricle, and is covered by the tela choroidea, which separates the thalamus from the fornix.

The thalamus is mainly composed of gray matter and many nuclei have been described inside it. The spatial distribution of these nuclei is rather complex, and only the gross structure is reported in this chapter. They are subdivided into three main groups: anterior nuclear group, medial nuclear group, and lateral nuclear group. The posterior part of the thalamus is the pulvinar. The three groups are separated by the internal medullary lamina, which has a "Y" shape.

A Motor Systems - II: Extrapyramidal System: Basal Ganglia; Thalamus - A) Sagittal Sections 2 1 7

Claustrum


Basal amygdaloid nucleus

E"

% - « ..4

r ,r* -.

Lateral amygdaloid nucleus

/ -

^ t -

A Motor Systems - II: Extrapyramidal System: Basal Ganglia; Thalamus - A) Sagittal Sections 219

Anterior limb of internal capsule

Putamen

Basal amygdaloid nucleus

Cortical amygdaloid nucleus

Posterior limb of internal capsule

*'r- "'**W -'•"

Caudate nucleus

Pulvinar


'*"*~^ " ' ^ . '•*' -rf?. , ' r

»^j^w»*<-, _

••*W

^

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Body of caudate nucleus

Head of caudate nucleus

Ventral lateral thalamic nucleus

Globus pallidus, pars medialis

Anterior commissure

1 r'^ " - ' ^ l i ^

^^x/^ % m r^%«-

1 ^ Lateral posterior thalamic nucleus

" ^ ' " '

Pulvinar

Ventral posterolateral thalamic nucleus


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r

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X^—IP

Red nucleus ~m i ^'

^ — - - , ^ < - „

Lateral dorsal thalamic nucleus

Mediodorsal thalamic nucleus

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i

Pulvinar

Centromedian thalamic nucleus

t ^ 1

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f


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Lateral dorsal ^ thalamic nucleus


Anterior . ' thalamic nucleus

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«i£j|i iyii^

Crus of fornix

;^ Mediodorsal "{' thalamic nucleus

Pulvinar

-f Centromedian , -g thalamic nucleus

^

I


•ICZi

Anterior thalamic nucleus


Anterior commissure

Fornix


^>J^

.^^-

Crus of fornix


Pulvinar

Hypothalamus

Mammillothalamic tract

Mammillary body (hypothalamus)


''^ ''^'\i


' / • \

1 y

Body of fornix

Thalamus

Interthalamic mass

Anterior commissure

Mam miliary body (hypothalamus)

f*tJ^

1

Habenular commissure


Pineal body

Great vein of Galen

Quadrigeminal plate or tectum of midbrain orcolliculi or quadrigeminal tubercles

V

1.1 1

A Motor Systems - II: Extrapyramidal System: Basal Ganglia; Thalamus - B) Coronal Sections 225

^ \ \

i

Anterior limb of internal

capsule

,y\"

\

- %


Putamen

Caudate-lenticular gray bridges

..SMISMcP'

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Y

Third ventricle

Hypothalamus -

Anterior cerebral artery m^

Optic nerve

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^ %


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of internal capsule

Putamen

Claustrum

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5 ? -T«

i j < ^ Nucleus accumbens

/ ^

^ ^

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External capsule - f

Extreme capsule ^

Claustrum —

Optic chiasm —

Pituitary stalk

Hypophysis (pituitary gland)

%J

m-

I

/

^

X


Anterior limb of Internal capsule

Putamen

Nucleus accumbens

Middle cerebral artery (Ml)

Anterior cerebral artery (A1)


V /

t^ ^


Columns of fornix

Claustrum

Hypothalamus

Anterior perforated substance ~^ ^

C 3 p l » ^ ^ ^ - - \ ^

'^,



^^- External capsule

Extreme capsule

Putamen

Globus pallidus, pars lateralis

Anterior commissure

l <

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r\Mv^:M

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1 I H : '-FI


Columns of fornix


Claustrum

Hypothalamus -



Internal capsule

External medullary lamina

Putamen


Internal medullary lamina


Basilar artery

^i

^ .# •- ^

IT 111*

I'S-

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V< Medial thalamic l

nucleus v*"

Ventral posterolateral

thalamic nucleus

Putamen


Claustrum



Pons -",

•^- ^ ^ ^ $ - :

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Somatosensory System

Epicritic and deep sensitivity from trunk and limbs is carried by the posterior fasciculus-medial lemniscus pathway. The fibers travel within the spinal cord omolaterally to their origin, in the gracile and cuneatus fascicles, ending in the corresponding dorsal column nuclei, in the posterior aspect of the caudal end of the medulla oblongata. Thereafter, the medial lemniscus originates, and it immediately crosses the midline ascending to the ventral posterior nucleus of the thalamus. The protopathic pathways arise from the dorsal horn of the spinal gray matter. The fibers, which relay pain and temperature sensations, decussate within the cord at the level of their origin, and ascend in the anterolateral funiculus (spinothalamic tract) to the thalamus, traveling together with the medial lemniscus in the brain. Projections from the thalamus reach the somatic sensory area, mainly located in the postcentral (parietal ascending) gyrus. Sensory fibers and terminations are somatotopically organized.

. B Sensory Systems -1: Somatosensory System 243

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248 Short introduction pp. 249-251

Gustatory System

Taste receptors or papillae can be seen on the tongue as little red dots, or raised bumps, particularly at the front of the tongue. They do not have an axon. Information is relayed onto terminals of sensory fibers by transmitter. These fibers derive from the ganglion cells of the cranial nerves VII and IX. The facial nerve (VII c.n.) carries taste sensations from the anterior two thirds of the tongue. Fibers come from the lingual nerve (branch of the trigeminal nerve), reach the chorda tympani and, through it, the facial nerve. The posterior third of the tongue is innervated by the glossopharyngeal nerve (IX c.n.). Cellular bodies are in the plexiform ganglion. Nervous fibers from both nerves terminate at the gustative nucleus (or Nageotte's, or solitary tract nucleus), located in the dorsolateral part of the medulla oblongata.

From there, information is projected to the somatosensory cortex for conscious perception of taste and to the hypothalamus, amygdala and insula, giving the so-called "affective" component of taste, for behavioral response, (e.g. aversion, gastric secretion, feeding behavior).

The functional meaning of the gustative cortex is not yet fully understood. More than a simple terminal station for consciousness of taste, it seems to represent part of a more complex circuit which governs the alimentary behavior.

The main cortical area of taste is the opercular cortex (able to de-codify four groups of stimuli: sweet, salt, sour, and bitter). From there, projections start to the orbitofrontal and prepiriform cortex.

B Sensory Systems - II: Gustatory System 249

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B Sensory Systems - II: Gustatory System 251

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Speech System

This is a complex functional system which includes sensorial, cognitive, and motor aspects. In a very elementary interpretation, a frontal (motor) area and a temporal (sensitive) area can be clearly distinguished and recognized in fMRI exams. The speech system is lateralized, being located in the left hemisphere of right-handed and of 70% of left-handed people.

The motor component, which, when impaired, is responsible for the so-called non-fluent aphasia, includes Brodmann's area 44, in the opercular part of the inferior orbital gyrus (termed Broca's speech area). Other authors consider area 45 as part of the Broca's area and area 46 as a marginal area compromise in non-fluent aphasia. In fluent aphasia the compro-mission includes temporal lobe. In the typical Wernicke's form, the lesion involves the posterior region of the left superior temporal gyrus or the first gyrus of the temporal lobe (areas 21 and 22). The damage often extends into the parietal lobe (angular gyrus, area 39). As Wernicke's area is adjacent to primary auditory cortex (Brodmann's areas 41 and 42), it can be considered an auditory association area. Conduction aphasia results from damage to the arcuate fasciculus, a bundle of nerve fibers that lies below the supramarginal gyrus in the temporal lobe and connects Broca's and Wernicke's areas. Both Broca's and Wernicke's areas are left intact. Affected areas may include superior temporal gyrus, insula, primary auditory cortex, auditory association areas (Brodmann's 21 and 22), and the supra-marginal gyrus (area 40). Transcortical sensory aphasia is an extremely rare form of fluent aphasia that occurs when Broca's area, Wernicke's area and the arcuate fasciculus are safe but disconnected from the rest of the brain, as a consequence of lesions in Brodmann's areas 37,22, and 39. Lesions in area 37 are known to cause anomia.

Brainstem Pathways and Nuclei

This chapter does not describe a single functional entity, seeing as the brainstem is a station in which several different and complex systems meet or run freely. However, from the viewpoint of topographic and radiological anatomy, the knowledge of circuits, pathways and nuclei in the brainstem needs special consideration. For this reason this topic has been inserted in the chapter "Functional Systems". MRI cuts have been com

pleted with drawings able to reveal the finest structures that are not visible with routine radiological exams and that start to be disclosed with modern imaging technology like MR tractogra-phy. These structures do not need additional description, and the reader is advised to look up single functional systems for any further details: brainstem nuclei are covered together with the related cranial nerves (see Chapter 4), the main ascending and descending pathways are covered in the specific functional system (see Chapter 5, pp. 204,242), while general morphology of the brainstem and its connections with the cerebellum are covered in Chapter 3.

Limbic System and Hippocampus

Based on Broca's classical definition (1878), this system includes subcallosal, cingulate, parahippocampal, and hip-pocampal gyri. Under a more modern interpretation, the dentate gyrus, amygdaloid nucleus, olfactory nerve, bulb and striae, septal area, anterior perforated substance, septum pellu-cidum, fornix, anterior commissure, and other smaller structures are included. The lymbic system is mainly involved in memory mechanisms and emotional states.

The hippocampus has a particular role: the term means "sea horse" and is due to its peculiar shape when seen in coronal cuts. The parahippocampal gyrus is situated inferiorly and forms the border between the inferior and medial surface of the hemisphere. Superiorly, it continues in the subiculum, toward the hippocampal fissure that delimitates the hippocampus. The hippocampal fissure is bordered above by the dentate gyrus and the fimbria, which is the inferior aspect of the fornix. Immediately above, the choroidal fissure is found, through which enters the choroidal plexus of the temporal horn of the lateral ventricle. Anteriorly, the hippocampus bends up and back to form an uncinate process, the "uncus". Fibers from the hippocampus go immediately below the ventricular ependy-ma. Beneath them there is a white layer, the alveus. Fibers from the alveus converge to form the fimbria of the fornix.

Commissural and Associative Pathways

Transverse or commissural fibers unite the two hemispheres; association fibers connect different structures in the same

hemisphere. Most commissural and associative pathways are well visible on cross-sectional MRI cuts. In this chapter, the main pathways are drawn on 3D MRI reformatted images. MR tractography can nowadays directly identify many of them.

• Corpus Callosum (see also p. 24) The corpus callosum is the biggest interhemispheric commissure, containing fibers that reach all aspects of the cerebral cortex. It has a central portion, the body or trunk, an anterior part, the genu, and a posterior one, the splenium. The genu bends dorsally and downward to form the rostrum. This becomes progressively thinner and goes toward the anterior commissure. This thinner part is called the "lamina terminalis". The genu's fibers curve forward and lateral to the frontal horns. This structure is called the "forceps minor". The passage between the body and the splenium is often narrow. This portion is also known as "isthmus". The corpus callosum delimitates the roof of the lateral ventricles. The splenium's fibers cover the lateral ventricles posteriorly and extend laterally to cover the lateral aspect of the temporal horn. They are termed the "tapetum", while the most posterior fibers, which curve backwards to the occipital lobes, are called the "forceps major".

• Anterior Commissure The anterior commissure is a bundle of myelinated fibers about 3 mm thick, located above the rostrum of the corpus callosum, anterior to the interventricular foramen of Monro. Its fibers connect the medial aspects of the temporal lobes and course laterally, producing a groove on the anterior inferior part of the lentiform nucleus.

• Superior Longitudinal Fasciculus The superior longitudinal fasciculus, or arcuate fascicle, extends from the frontal to the parietal and occipital lobes. It goes laterally to the corona radiata. Among its fibers, the pathway between the speech areas of Broca and the Wernicke's are included.

• Fasciculus Occipito-Frontalis It extends from the occipital pole to the frontal lobe, passing laterally to the caudate nucleus. Two portions are distinguished: the fasciculus occipito-frontalis superior and the inferior.

• Inferior Longitudinalis Fasciculus This fascicle starts from the occipital pole and extends to the temporal lobe passing laterally to the lateral ventricle.

• Uncinate Fasciculus It connects the orbital gyri of the frontal lobe and the speech area with the cortex of the temporal lobe, passing below the claustrum, the external and the extreme capsules.

C Speech System 253

• Posterior Commissure This structure is located immediately below the pineal gland, on the dorsal aspect of the midbrain, in correspondence with the beginning of the cerebral aqueduct. It is related to the habe-nular commissure, which is located above, adjacent to the pineal body.

• Habenular Commissure This commissure is specifically devoted to connecting the two habenular nuclei with each other. These nuclei are located on the dorsomedial aspect of the thalami.

• Fornix The fornix is the main hypothalamic commissure. Its morphology is described in Chapter 1 (page 24).

• Mammillothalamic Tract The fibers of the mammillothalamic tract extend from the mammillary body, across the thalamus, to end in the anterior thalamic nuclei. It is adjacent to the third ventricle wall, in the hypothalamus.

• Short Arcuate Fibers These fibers connect adjacent gyri. They are also called "U" Fibers.

Neuroendocrine System

This system is essentially composed of the hypothalamus and the pituitary gland. The system has the particular task of producing hormones. Therefore, a very particular circulation is present.

I. Hypothalamus

The hypothalamus is situated below the thalamus and the basal gangUa, and forms the lateral wall of the lower aspect of the third ventricle, separated from the thalamus by the hypothalamic sulcus. It contains several complex nuclei, the mammillary bodies, anterior to the interpeduncular fossa, the tuber cinereum (a protuberance located behind the infundibulum), the infundibulum, the pituitary stalk, the lamina terminalis and the anterior commissure.

II. Pituitary Gland

The pituitary gland is median, and strongly connected to the hypothalamus by means of the stalk. The gland varies in size and approximately reaches the adult shape and volume by the age of 4. The height of the gland, however, varies over time and in consequence of the hormonal state. In males, it measures about 4 ± 1 mm, in females 4.4 ± 1.4 mm. In females, however, the height is more variable, being more pronounced in fertile life (about 6-7 mm), reaching 10 mm during adolescence and 12 mm during pregnancy.

The gland is composed of two lobes: the anterior, embry-ologically derived from the I branchial arch (Rathke's pouch), and the posterior, which derives from the hypothalamus. In between is a thin layer, the pars intermedia, that sometimes takes a cystic aspect. It is located inside the sella turcica, covered by the tentorium sellae, a dura mater plica perforated in the middle to leave a passage for the stalk. Laterally, the gland is delimited by the cavernous sinuses. There is no dural wall to delimitate the medial aspect of the cav-

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Area 45 (Broca's speech area)

Area 44 (Broca's speech area)

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Area 42 (Primary auditory area)

Area 22 (Wernicke's speech area)

Area 21 (Wernicke's speech area;

Area 37 (Sensory speech marginal area)

Area 40 (Sensory speech marginal area

Area 39 (Sensory speech marginal area

ernous sinus, while the lateral wall is thick, formed by a dural plica. The dura mater of the lateral wall contains the cranial nerves III, IV, VI and V2. The cranial nerve VI passes inside the sinus.

III. Vascularization

The hypothalamus is richly supplied by several small arteries coming from both carotids and Willis' circle. The anterior lobe of the pituitary gland is suppUed by superior pituitary arteries coming from the internal carotid and by posterior communicating arteries. They wrap the upper stalk, where they form an initial capillary network and a group of draining veins. These reach the anterior pituitary lobe, where a second capillary plexus is formed (pituitary portal system). This system receives anterior pituitary hormones. Finally, some principal venous ducts drain the blood toward the cavernous sinus.

The posterior lobe of the gland receives supply directly from internal carotid arteries, by means of posterior pituitary arteries. The venous drainage is to the cavernous sinus.

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C Speech System 255

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D Brainstem Pathways and Nuclei 257

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E Limbic System and Hippocampus 263

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Regions of activation obtained during a "face memory" task. The fusiform gyrus activation seems more directly related to prosopognosic function. Courtesy of M. Caulo, MD, PhD, ITAB, Chieti

F Commissural and Associative Pathways 275

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G Neuroendocrine System 277

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Cerebrospinal Fluid System

The cerebrospinal fluid (CSF) is located within the ventricles and subarachnoid spaces in the brain and spine. Its composition schematically contains 0-5/|il (0-5 x 10 /I) cells, 40-80 mg/dl glucose, 15-60 mg/dL protein. The principal source of CSF is represented by the choroid plexi of the lateral, third and fourth ventricles. The total volume is approximately 140-150 ml, 30-40 of which is in the ventricular system, with a production rate of about 20 ml/h and a turnover rate of about 5 h. The CSF moves within the ventricles and subarachnoid spaces under the influence of hydrostatic pressure generated by its production and a complex pushing system dependent on internal carotid pulsation in systole and negative pressure in the superior sagittal sinus during diastole. The CSF cushions the brain, regulates brain extracellular fluid, and allows the distribution of neuroactive substances. The choroid plexi are fringe-like processes of the pia mater which project into the ventricular cavity. They consist of minute and highly vascular villous processes, each with an afferent and an efferent vessel. The arteries of the plexus are the anterior choroidal artery, a branch of the internal carotid that enters the plexus at the end of the temporal horn, and the posterior choroidal arteries, branches of the posterior cerebral artery. The veins of the choroid plexus join the internal cerebral vein. The tela choroidea of the fourth ventricle lies on the roof of the ventricle and adheres to it, reaching the foramen of Magendie. Two lateral thickenings, the choroid plexuses, extend along the lateral foramina of Lusch-ka. Under normal conditions, 90% of CSF is drained by dur-al venous sinuses. The remaining rate is mostly absorbed by white matter deep veins. The CSF circulates from the lateral and third ventricles toward the fourth ventricle through the cerebral aqueduct, and from here it reaches the cerebral convexity, the granulation of Pacchioni, and the superior sagittal sinus. The flow is pulsatile and synchronized with the heartbeat.

H Cerebrospinal Fluid System 289

Pineal recess

Interthalamic mass ^ -^^^ Suprapineal recess

Lateral ventricles: bodies

Lateral ventricles: frontal horns ^^

Interventricular foramina of Monro -

III ventricle

Optic recess

Infundibular recess


Lateral ventricles: trigones

Lateral ventricles: occipital horns

IV ventricle

IV ventricle: lateral recess

IV ventricle: lateral foramen of Luschka

Obex

Lateral ventricles: temporal horns

^ h * ^ ^ -r „ i _ _ IV ventricle: midline foramen of Magendie

_ Central canal of spinal cord


Posterior basal cistern

Choroid plexus of the IV ventricle -

in the foramen of Luschka

Foramen of Magend

Cisterna magna (cerebello-medullaris cistern)

ie -^

f

\

Basilar artery

Pontine cistern

Cerebollopontine angle cistern

IV ventricle

Lateral recess of the IV ventricle with choroid tela


Cistern of sylvian fissure (insular cistern)

Cistern of sylvian fissure (insular cistern)

I ventricle {

Optic recess

Infundibular recess


and choroid plexus

Ambiens cistern

Cerebral aqueduct of Sylvius J ,

Tectal cistern (quadrigeminal cistern)

i

\

J \

\\

\ >

•6-X.

f

k

ventricle

Cistern of the great vein (of Galen)

Glomus of choroid plexus ^^ of the lateral ventricle i

Lateral ventricle, trigone

Superior cerebellar cistern

Lateral ventricle, occipital horn


Pericallosal cistern

Cistern of velum interpositum

Interhemispheric cistern

Lateral ventricle, frontal horn ^

Lateral ventricle ^

Intraventricular foramen j (of Monro) containing - 1

choroid tela w

Stria medullaristhalami —|-

1 Choroid vein - '•

Glomusof choroid plexus ^ of the lateral ventricle

Vein of Galen ^

/ /

t

•

V

h

\

' l ? ! ***

Superior sagittal Lateral ventricle, sinus trigone

/ •

"''*'•'•

Interhemispheric cistern

Lateral ventricles, bodies

Choroid plexuses of lateral ventricles


Pericallosal cistern

Lateral ventricle

I ventricle —,

Cistern of the lamina terminalis —

y'j

Chiasmatic cistern ^ j f L * i * * -^ ' * '^"^

Interpeduncular cistern

Pontine cistern

V

> • * ' * * ^ > " " - " " ' 5 ! J " 3 U .

/

\

Cistern of velum interpositum (cistern of transverse fissure)

Cistern of the great cerebral vein (of Galen)


^ Superior cerebellar cistern

- Cerebral aqueduct of Sylvius

-'- IV ventricle

~~ Choroid tela of IV ventricle

Foramen of Magendie

^ Cisterna magna (cerebello-medullaris cistern)

<r 4


, - - ; j f /

Lateral ventricle —

Choroid tela of lateral ventricle


Interpeduncular cistern ^ v

Lateral recess of the IV ventricle

- Choroid tela of IV ventricle


Inferior sagittal sinus

Choroid tela of the lateral ventricle


Pineal recess of the III ventricle

Suprapineal recess of the III ventricle

Choroid tela of the interventricular foramen (of Monro) ^

Lamina terminalis

*..** '"V.

„mm^f^ J ^ ^

Vein of Galen

- Pineal gland

Infundibular recess

Optic recess

Optic chiasm -

Pituitary stalk

*J

~~ Posterior commissure

Interthalamic mass Choroid tela ofthe III ventricle


Choroid tela in the III and lateral ventricles Inferior sagittal sinus

Interventricular forannen (of Monro)



Lamina ternninalis

Straight sinus

Vein of Galen


6 Vascular Anatomy

298 Short Introduction pp. 299-339 .

Intracranial Arteries

I. Carotid Artery and Branches

The internal carotid artery supplies the anterior part of the brain and the eye, and sends branches to the forehead and nose. According to the latest classifications, it can be divided into seven segments: cervical, petrous, lacerum, cavernous, cli-noid, ophthalmic, and communicating.

• Cervical portion (CI): it begins at the bifurcation of the common carotid, and runs upward to the carotid canal.

• Petrous portion (C2): it corresponds to the petrous portion of the temporal bone. Here, the artery ascends at first (vertical segment), and then curves medialward (horizontal segment), surrounded by the sympathetic carotid plexus.

• Lacerum portion (C3): it extends from the endocranial carotid canal to the petrolingual ligament, and ascends in the carotid sulcus of the basisphenoid. It is separated from the trigeminal ganglion by a thin bony lamina or a fibrous membrane.

• Cavernous portion (C4): it is situated inside the cavernous sinus. It perforates the dura mater forming the roof of the sinus and exits medial to the anterior clinoid process.

• Clinoid Portion (C5): it is the shortest part of the ICA, completely intradural. It comprises only the small superior segment of the anterior ICA genu, between the proximal and distal dural rings.

• Ophthalmic portion (C6): it begins after the distal dural ring, thus representing the first subarachnoid tract. It ends proximal to the posterior communicating artery origin.

• Communicating portion (C7): it starts immediately before the origin of the posterior communicating artery, passes between the optic and oculomotor nerves and reaches the anterior perforated substance at the medial extremity of the lateral cerebral fissure, where it gives off its terminal branches.

The cervical portion of the ICA has no branches. Branches from the other portions are:

1. The tympanic branch - a small branch, it enters the tympanic cavity through a minute foramen in the carotid canal, and anastomoses with the anterior tympanic branch of the internal maxillary and with the stylomastoid artery.

2. The artery of the pterygoid canal (vidian artery) - small, inconstant.

3. The cavernous branches supply the hypophysis, the semilunar ganglion, and the walls of the cavernous and inferior petrosal sinuses. Some of them anastomose with branches of the middle meningeal.

4. The hypophyseal branches are one or two in number and supply the pituitary gland.

5. The anterior meningeal branch (a. meningea anterior) is a small branch which passes over the small wing of the sphenoid to supply the dura mater of the anterior cranial fossa;

6. The ophthalmic artery arises from the internal carotid as the latter emerges from the cavernous sinus and enters the optic canal, below and lateral to the optic nerve. It then passes over the nerve, proceeds anteriorly, and divides into terminal branches (see p. 126);

7. The anterior cerebral artery (ACA) (a. cerebri anterior) passes above the optic nerve. In the longitudinal fissure, it is connected by a short trunk (the anterior communicating artery) to the opposite one. This landmark subdivides the artery into segments Al (or horizontal or precommunicating segment), and A2 (or vertical or postcommunicating segment). Distal and cortical branches are also termed A3. The artery runs in the longitudinal fissure around the corpus callosum until its posterior part, where they end by anastomosing with the posterior cerebral arteries. In its course, the anterior cerebral artery gives off the following main branches: the antero-medial perforating arteries are a group of small arteries which supply the rostrum of the corpus callosum, the septum pellucidum, and the head of the caudate nucleus (recurrent artery of Heubner). The inferior branches supply the olfactory lobe, gyrus rectus, and internal orbital gyrus. The anterior branches supply a part of the superior frontal gyrus, and part of the superior and middle frontal gyri and upper part of the anterior central gyrus. The most prominent is the frontopolar artery. The middle branches supply the corpus callosum, the cingulate gyrus, the medial surface of the superior frontal gyrus, and the upper part of the anterior central gyrus. The posterior branches supply the precuneus and adjacent lateral surface of the hemisphere.

8. The middle cerebral artery (MCA) (a. cerebri media) is the largest branch of the internal carotid. It runs at first lateral-ward in the lateral cerebral or sylvian fissure and then backward and upward on the surface of the insula, where it di

vides into a number of branches which are distributed to the lateral surface of the cerebral hemisphere. It can be divided into four segments: Ml or horizontal segment, which runs horizontally below the anterior perforated substance, bifurcates or trifurcates in its lateral third and ends at the limen insulae, by turning posterosuperiorly; M2 or insular segments are 6 to 8 in number, lie on the cortical surface of the insula and terminate at the top of the circular gyrus; M3 or opercular segments follow and terminate at the surface of the lateral cerebral fissure; M4 or cortical segments are the distal branches extended over the hemispheric surface. The middle cerebral artery supplies the following main branches: the antero-lateral perforating a., small arteries which supply the inner segments of the lentiform nucleus, the caudate nucleus, the internal capsule, and the thalamus. The inferior lateral frontal a. supplies the inferior frontal gyrus (Broca's convolution) and the lateral part of the orbital surface of the frontal lobe. The ascending frontal a. suppHes the anterior central gyrus. The ascending parietal a. is distributed to the posterior central gyrus and the lower part of the superior parietal lobule. The parietotemporal a. suppUes the supra-marginal and angular gyri, and the posterior parts of the superior and middle temporal gyri. The temporal branches are distributed to the lateral surface of the temporal lobe.

9. The posterior communicating artery (a. communicans posterior) arises from the back side of the internal carotid, and anastomoses with the posterior cerebral artery. From its posterior half some perforating arteries arise, which supply the medial surface of the thalamus and the walls of the third ventricle.

10. The anterior choroidal artery (a. choroidea; choroid artery) is a small branch that arises from the internal carotid, close to the posterior communicating artery. It enters the inferior horn of the lateral ventricle through the choroidal fissure and ends in the choroid plexus.

11. Vertebral Artery and Branches

The vertebral artery can be divided into four segments: VI or extraosseus (from the subclavian artery to C6), V2 or foram-inal (from C6 to axis), V3 or extraspinal (from CI to foramen magnum), V4 or intradural (from foramen magnum to basilar junction).

The artery gives rise to cervical branches destined to spine and muscles; meningeal branches (anterior and posterior

A Intracranial Arteries 299

meningeal branches of the V.A.), and intracranial arteries: anterior and posterior spinal arteries; postero-inferior cerebellar artery (PICA).

The anterior spinal artery arises from both distal vertebral arteries from two branches that fuse on the midline. It supplies the anterior surface of the medulla. The posterior spinal artery originates from the distal VA or from the PICA. The PICA has four segments and originates from the distal part of the VA. The first or anterior segment goes lateralward toward the cerebellar olive; the second or lateral continues posteriorly in the cerebel-lo-medullary cistern, forming a caudal loop; the third or posterior medullary segment turns upward behind the posterior medullary velum. The fourth or supratonsillar segment gives the second, cranial loop and courses above the cerebellar tonsil.

By the fusion on the midline of both vertebral arteries, the basilar artery is formed.

III. Basilar Artery and Branches

The basilar artery (BA) starts from the vertebral artery confluence and ends at its subdivision into the two posterior cerebral arteries. Its main branches are:

1. Pontine perforating arteries They are median, paramedian, and lateral perforating branches destined to supply the midbrain.

2. Anterior inferior cerebellar artery (AICA) It is the smallest of the three cerebellar arteries. It courses posteriorly, ventromedial to the facial and vestibulocochlear nerve, giving rise in 50 % of cases to the

3. Internal auditory (labyrinthine) artery. In the remaining cases, this artery can originate directly from the basilar artery or from the PICA. It follows facial and vestibulo-cochlear nerves in the internal acoustic canal. The AICA terminates by coursing over the anterolateral aspect of the cerebellum.

4. Superior cerebellar artery (SCA) It arises immediately before the basilar artery bifurcation. It courses posterolaterally, below the oculomotor nerve, then curves around the midbrain.

5. Posterior cerebral artery (PCA) It is the terminal branch of the BA. During its course it furnishes important collaterals (posterior thalamoperforating, medial posterior choroidal, lateral posterior choroidal and cortical arteries). Anatomically, it is divided into four portions:

Maxillary Artery

"Hairpin" shape at the cross with

the zygomatic bone

Middle deep temporal artery

Anterior deep temporal artery

Middle meningeal

artery

Transverse facial artery

Maxillary artery

Inferior alveolar artery

Masseteric artery

Facial artery

Infraorbital artery

Sphenopalatine arteries and nasal branches

Superficial temporal artery

Middle deep temporal artery

. Middle ^ meningeal

artery

- Maxillary artery

Greater Superior (descending) posterior

palatine artery alveolar artery

Buccal Transverse branches facial

artery

External Carotid Artery

Superficial temporal artery

Scalp's branches

Occipital artery

Muscular branches

3 0 0 6 Vascular Anatomy

PI or precommunicating or mesencephalic segment, which Hes in the interpeduncular cistern, curving around the midbrain and ending at its junction with the posterior communicating artery. This segment gives off perforating branches destined to the midbrain and thalamus. P2 or ambient segment, which extends to the posterior aspect of the midbrain; P3 or quadrigeminal segment, which goes from the quadrigeminal plate to the calcarine fissure. Sometimes it subdivides into two arteries; P4 or calcarine fissure includes the terminal branches (parieto-occipital and calcarine arteries, cortical branches).

Internal Carotid Artery

C7

C5

f •C I ^ ""^Jlg ^ Ophthalmic artery

Anterior choroidal artery


C4

C4

C3

'i ' I " ^

Bouthillier

.1

— Anterior choroidal artery


C4

Fischer



Middle internal frontal artery

Posterior internal frontal artery

Anterior internal frontal artery

Frontopolar artery

Orbitofrontal artery t'*" >

Ophthalmic artery

Internal carotid artery: clinoid segnnent (C5)

Internal carotid artery: cavernous segment (C4)

Pericallosal artery

Rolandic artery

Superior internal parietal artery

Inferior internal parietal artery

Fronto-opercular artery (prefrontal artery, prerolandic artery)

Anterior parietal artery

Posterior parietal artery

Angular artery

Posterior temporal artery

Internal carotid artery: communicating segment (C7)

Internal carotid artery: lacerum segment (C3)

Internal carotid artery: ophthalmic segment (C6)

Internal carotid artery: cervical segment (CI)

Internal carotid artery: petrous segment (C2)

302 6 Vascular Anatomy


Pericallosal artery

Anterior cerebral artery: pre-communicating segment(AI)

Middle cerebral artery: pre-bifurcation Ml segment

Internal carotid artery: clinoid segnnent {C5)

Internal carotid artery: cavernous segnnent (C4)



Anterior cerebral artery (bifurcation)

Anterior cerebral artery: postcommunicating segment (A2)

Internal carotid artery: communicating segment (C7)





Medial lenticulostriate arteries

Lateral lenticulostriate arteries

Middle cerebral artery: opercular segment (M3)

Middle cerebral artery: insular segment (M2)

Middle cerebral artery: pre-bifurcation Ml segment

Middle cerebral artery: post-bifurcation Ml segment



Callosomarginal artery

Pericallosal artery

Anterior cerebral artery (bifurcation)

Anterior cerebral artery: post-communicating segment (A2)

Anterior cerebral artery: pre-communicating segment (A1)

Anterior communicating artery


/* Internal carotid artery: clinoid segment (C5)

Internal carotid artery: cavernous segment (C4)



Basilar artery


Middle cerebral artery: pre-bifurcationMI segment

Anterior cerebral artery: pre-communicating segment (A1)


^

ti Ki

Anterior cerebral artery: post-communicating segment (A2)



Posterior cerebral artery: quadrigeminal segment (P3)


Posterior cerebral artery: ambient segment {P2)

Temporal branches

Posterior cerebral artery: calcarine segment (P4)

Posterior cerebral artery: pre-communicating segment (PI)



Anterior cerebral artery: post-communicating segment {A2)



Anterior cerebral artery: pre-communicating segment (Al)

Posterior cerebral artery: ambient segment (P2)

Posterior cerebral artery: horizontal or precommunicating segment (PI)

Middle cerebral artery: prebifurcation Ml segment

Middle cerebral artery: Insular segment (M2)

Middle cerebral artery (knee)

Middle cerebral artery: postbifurcation Ml segment


Basilar artery Internal carotid artery









Anterior cerebral artery: precommunicating segment (Al)



Temporal branches


Basilar artery





Anterior cerebral artery: precommunicating segment (A1)



Basilar artery






Temporal branches





Internal carotid artery ~


Y w\

Basilar artery A





Temporal branches



Middle cerebral artery: cortical segment (M4)

Posterior cerebral artery: precommunicating segment (PI)



Temporal branches

Posterior cerebral artery: ambient segment {P2)





Internal carotid artery -

Basilar artery -

X J







j /

1 / ! / -







Temporal branches

Basilar artery Posterior cerebral artery: calcarine segment (P4)






Middle cerebral artery: postbifurcation M1 segment

Anterior temporal artery

Middle cerebral artery: / insular segment (M2)

Middle cerebral artery: prebifurcation M1 segment



Basilar artery




Middle cerebral artery (knee) Posterior cerebral artery: quadrigeminal segment (P3)




V_ Posterior cerebral artery: ambient segment (P2)




Antero-inferior cerebellar artery (AICA) - Basilar artery




Middle cerebral artery: postcommunicating Ml segment

Middle cerebral artery: precommunicating Ml segment

Internal carotid artery -.

\





Posterior cerebral artery: precommunicating segment (P1)

Superior cerebellar artery (SCA)

Antero-inferior cerebellar artery (AICA) - Basilar artery



Middle cerebral artery: prebifurcation Ml segment "






> • • € f


Anterior temporal artery


Basilar artery


Antero-inferior cerebellar artery (AICA) Temporal branches


Vertebrobasilar System

Calcarine artery



Inferior temporal arteries


Cerebellar branches of the SCA

Basilar artery

Right vertebral artery

Parieto-occipital artery

— Superior vermian branch of SCA



Antero-inferior cerebellar artery (AICA)

Postero-inferior cerebellar artery (PICA)

Left vertebral artery




Calcarine artery —



Inferior temporal arteries


Basilar artery

Thalamoperforating arteries


Posterior temporal artery


Postero-inferior cerebellar artery (PICA)

Vertebral artery: intradural segment (V4)

Vertebral artery (V3 segment)

Antero-inferior cerebellar artery (AICA) Vertebral artery: foraminal segment (V2)



Lateral-posterior choroidal arteries

Medial-posterior choroidal arteries

Posterior thalamoperforating arteries

Anterior thalamoperforating arteries

Posterios temporal branches

Basilar artery


Antero-inferior cerebellar artery (AICA) --

Anterior and lateral segments of PICA ^

Splenial branches (posterior pericallosal artery)


Superior vermian branches of SCA

Calcarine artery

Supratonsillar segment of PICA

Posterior medullar segment of PICA

Hemispheric branches of PICA

Vertebral artery — - Caudar'loop"of PICA

B Arterial Vascular Territories 319

\

>.<y •

^ B Anterior cerebral artery

^ B Middle cerebral artery

^ B Posterior cerebral artery

^ B Antero-inferior cerebellar artery

i j p Postero-inferior cerebellar artery

^ B Superior cerebellar artery


/

'"'"""'.-.

k ^ '

\

^

/

k

•

•

•

•

«

•

- •

1





Postero-inferior cerebellar artery


Anterior choroidal and anterior thalamoperforating arteries


^ P Anterior cerebral artery

^ ^ Middle cerebral artery

^ ^ Posterior cerebral artery

^ ^ Antero-inferior cerebellar artery

n j f Postero-inferior cerebellar artery



Lateral lenticulostriate branches (from middle cerebral artery)


? WF->

^ p Anterior cerebral artery

• P Posterior cerebral artery

^ p Antero-inferlor cerebellar artery

U P Postero-inferlor cerebellar artery

^ p Superior cerebellar artery


Lenticulostriate branches (from middle cerebral artery)

Medial lenticulostriate and callosal perforating arteries (from anterior cerebral artery)

Posterior choroidal and posterior thalamoperforating arteries


^ . . - . . j |

^ p Anterior cerebral artery

^ P Posterior cerebral artery

( | ^ Postero-inferior cerebellar artery

^ P Superior cerebellar artery

s Lenticulostriate branches (from middle cerebral artery)


0.'^\ /

Posterior choroidal and posterior thalamoperforating arteries

Perforating branches of basilar artery

Perforating branches of vertebral artery


f t

y

A

^ B Anterior cerebral artery

^ B Posterior cerebral artery

n ^ Postero-inferior cerebellar artery



Posterior choroidal and posterior thalamoperforating arteries (from posterior cerebral artery)


Perforating branches of vertebral artery

6 Arterial Vascular Territories 325

^

• • / ^



Medial lenticulostriate arteries and callosal perforating arteries (fronn anterior cerebral artery)






Medial lenticulostriate arteries and callosal perforating arteries (from anterior cerebral artery)

Lateral lenticulostriate branches (fronn nniddle cerebral artery)









Perforating branches of the basilar artery




Medial lenticulostriate and callosal perforating arteries (from middle cerebral artery)



Perforating branches of the basilar artery

^h

ik ^m m^


1 ^ ^ Postero-inferior cerebellar artery

Perforating branches of the vertebral artery


^ P Middle cerebral artery

^ P Posterior cerebral artery

^ P Antero-inferior cerebellar artery

IP^ Postero-inferior cerebellar artery

^ P Superior cerebral artery


• *




^ 1 ^ Postero-lnferior cerebellar artery


r

V Perforating branches of vertebra I artery


^S Postero-inferior cerebellar artery ^ « ^ (* lateral medullary segment)

tp^'


^ .

^

%

i ^ Postero-inferior cerebellar artery

^ P Antero-inferior cerebellar artery




i




Posterior choroidal and anterior thalamoperforating arteries






\ Middle cerebellar artery


^ ^ Medial lenticulostriate and callosal ^ P perforating arteries

J (from anterior cerebral artery)



^


Anterior choroidal and anterior thalannoperforating arteries



Medial lenticulostriate and callosal perforating branches (from anterior cerebral artery)

. g^ Lateral lenticulostriate branches ^ P (from middle cerebral artery)

B Arterial Vascular Territories 3 3 7

Vascular Territories: Anterior Cerebral Artery

Vascular Terrritories

The color intensity is directly proportional to the frequency of distribution. For example, in this case, the area in dark red indicates the distribution of the anterior cerebral artery identifiable in 100% of the population. The surrounding area in lighter shades expresses the possible extension of vascularity in relation to individual variability in progressively decreasing percentages.

-^j^


Vascular Territories: Middle Cerebral Artery

. ' i C -

^l*sf-f*^^

1 . "^-L. ~

B Arterial Vascular Territories 3 3 9

Vascular Territories: Posterior Cerebral Artery

#*--*K^^ir* '^'^

: * i j C -

3 4 0 Short Introduction pp. 341 -352

Veins and Dural Sinuses

I. Cerebral Veins

The cerebral veins are divided into two groups: external and internal, depending on whether they drain the outer or inner parts of the brain.

The external veins are the superior, middle and inferior cerebral veins.

The superior cerebral veins (w. cerebri superiores), eight to twelve in number, drain the superior, lateral, and medial surfaces of the hemispheres. They open into the superior sagittal sinus.

The middle cerebral vein (v. cerebri media; superficial sylvian vein) runs along the lateral cerebral fissure and ends in the cavernous sinus. It is connected with the superior sagittal sinus through the great anastomotic vein of Trolard, which opens into one of the superior cerebral veins; with the transverse sinus through the posterior anastomotic vein of Labbe, which passes over the temporal lobe.

The inferior cerebral veins drain the lower surfaces of the hemispheres. Those on the orbital surface of the frontal lobe join the superior cerebral veins, and the superior sagittal sinus; the temporal ones drain into the middle cerebral and basal veins.

The basal vein is formed at the anterior perforated substance by the union of a small anterior cerebral vein, the deep middle (deep sylvian) cerebral vein, and the inferior striate veins. The basal vein goes around the cerebral peduncle and ends in the internal cerebral vein (vein of Galen); it receives small veins from the interpeduncular fossa, the hip-pocampal gyrus, and the midbrain.

The internal cerebral vein (w. cerebri interna) is formed by the choroid vein and the terminal vein (v. ter-minalis; vena corporis striati). The former originates between the corpus striatum and the thalamus, and drains the deep parts of the hemisphere. Beneath the splenium of the corpus callosum the internal cerebral vein joins the contralateral, and receives the corresponding basal vein, thus forming the great cerebral vein (v. cerebri magna; great vein of Galen).

The cerebellar veins are arranged in two sets: superior and inferior. The superior cerebellar veins cross the superior vermian surface, and end in the straight sinus and the inter

nal cerebral veins. The inferior cerebellar veins end in the transverse, superior petrosal, and occipital sinuses.

II. Dural Sinuses

The dural sinuses are blood channels situated between the two layers of the dura mater and covered by endothelium that is continuous with that of the veins. They are:

Superior sagittal, inferior sagittal, straight, transverse, sigmoid, occipital, cavernous, superior petrosal, intercavernous, inferior petrosal, basilar plexus.

1. The superior sagittal sinus occupies the convex margin of the falx. It starts at the foramen cecum, where it receives a vein from the nasal cavity. It runs backwards, lying in midline, in the inner surface of the skull, until the occipital protuberance, where it deviates (usually to the right side), and continues with the corresponding transverse sinus. The confluence of the sinuses (confluens sinuum; torcular Herophili) is its dilated extremity, located in correspondence with the internal occipital protuberance. The transverse sinus derives from it. The superior sagittal sinus is triangular in section, narrow in the front, and gradually increases in size as it passes backwards. Small openings communicate with irregular venous spaces (venous lacunae) in the dura mater near the sinus; there are usually three, on either side: a small frontal, a large parietal, and a medium-size occipital. Most cerebral veins and arachnoid granulations (pacchionian bodies) open into these lacunae.

2. The inferior sagittal sinus (sinus sagittalis inferior; inferior longitudinal sinus) is in the posterior half or two-thirds of the free margin of the falx cerebri and ends in the straight sinus. It increases in size towards the back, as it receives several veins from the falx cerebri, and some inconstant ones from the medial surfaces of the hemispheres.

3. The straight sinus (sinus rectus; tentorial sinus) lies at the line of junction of the falx cerebri with the tentorium cerebelli. It proceeds backwards and runs downward and backwards from the end of the inferior sagittal sinus to the transverse sinus opposite to the one into which the superior sagittal sinus is prolonged, communicating through a cross branch with the confluence of the sinuses. It drains blood from the inferior sagittal sinus, being

its natural prolongation, the great cerebral vein (great vein of Galen), and the superior cerebellar vein.

4. The transverse sinus (sinus transversus; lateral sinus), is paired in number and large. It begins at the internal occipital protuberance, one (usually the right) being the direct continuation of the superior sagittal sinus, the other, of the straight sinus. Each transverse sinus passes laterally and forward to reach the base of the petrous portion of the temporal bone, and lies in the attached margin of the tentorium cerebelli;

5. The sigmoid sinus is the continuation of the transverse one, beginning when it leaves the tentorium and curving downward and medially to reach the jugular foramen. Before it ends in the internal jugular vein, there is an enlargement called the jugular bulb. In its course it rests upon the squama of the occipital, the mastoid angle of the parietal, the mastoid part of the temporal. They receive blood from the superior petrosal sinuses, from the veins of the pericranium by means of the mastoid and condyloid emissary veins, and from the inferior cerebral and inferior cerebellar veins.

6. The occipital sinus (sinus occipitalis) is the smallest of the cranial sinuses. It is situated in the attached margin of the falx cerebelli, begins around the margin of the foramen magnum from several small veins, and ends in the confluence of the sinuses.

7. The cavernous sinus (sinus cavernosus) is paired and has a reticulated structure due to numerous fibrous filaments that traverse it. It is irregular, placed on either side of the body of the sphenoid bone, from the superior orbital fissure to the apex of the petrous bone. On its medial portion, it contains the internal carotid artery and the abducent nerve; on its lateral wall are the oculomotor, the trochlear, and the ophthalmic and maxillary nerves. The cavernous sinus drains blood from the superior ophthalmic vein through the superior orbital fissure, from some of the cerebral veins, and from the small sphenoparietal sinus, which courses along the lower surface of the small wing of the sphenoid. It communicates with the transverse sinus by means of the superior petrosal sinus; with the internal jugular vein through the inferior petrosal sinus; with the pterygoid venous plexus through the foramen Vesalii, foramen ovale, and foramen lacerum, and with the angular vein through the ophthalmic vein. The two sinuses also communicate with each other

C Intracranial Veins 341

by means of the anterior and posterior intercavernous sinuses.

8. The intercavernous sinuses (sini intercavernosi) are two, an anterior one and a posterior one, and connect the two cavernous sinuses passing in front of, and behind, the pituitary gland. Together with the cavernous sinuses, they form a venous circle (circular sinus) around the hypophysis.

9. The superior petrosal sinus (sinus petrosus superior) is small and narrow, and connects the cavernous with the transverse sinus going lateralward and backward in the attached margin of the tentorium cerebelli and in the superior petrosal sulcus of the temporal bone. It receives some cerebellar and inferior cerebral veins, and veins from the tympanic cavity.

lO.The inferior petrosal sinus (sinus petrosus inferior) is located in the inferior petrosal sulcus formed by the junction of the petrous bone with the occipital bone. It begins in the cavernous sinus and ends in the superior part of the bulb of the internal jugular vein. The inferior petrosal sinus receives the internal auditory veins and veins from the medulla oblongata, pons, and lower surface of the cerebellum.

11. The basilar plexus (plexus basilaris; transverse or basilar sinus) consists of several interlacing venous channels between the layers of the dura mater. It connects the two inferior petrosal sinuses lying over the basi-occipital bone.

Internal jugular vein

Sigmoid sinus -

Transverse sinus

S r


Torcular Herophili (sinus confluence)


Cortical veins Superior sagittal sinus

Transverse sinus

Sigmoid sinus

K



Cortical veins — ^


Vein of Trolard

Vein of Labbe

Straight sinus

Signnoid sinus —

Transverse sinus


Cortical veins

Vein of Galen ^


Middle cerebral vein

Veinof Trolard


Transverse sinus

Sigmoid sinus -

f

X- ^ • '


Veinof Labbe

Basal vein of Rosenthal

Straight sinus


Cortical veins -



Thalamostriate vein -

Middle cerebral vein

Vein of Trolard

Vein of Labbe

^.k. ,

" ^ ^

y

Vein of Galen


Straight sinus


Transverse sinus

Sigmoid sinus


Cortical veins ^

Internal cerebral vein ^

Inferior sagittal sinus —

Basal vein of Rosenthal -

Carotid siphon —

Superior petrosal sinus ^

Inferior petrosal sinus ^

Jugular bulb ^

Internal jugular vein ^

f if

/


Vein of Galen

Veinof Labbe

Straight sinus


Transverse sinus

Sigmoid sinus


^^.^T«g-n?^--*^«e>ppi^p^l^pi^i^.

Inferior vermian vein

Hemispheric cerebellar vein

Petrosal vein

Sigmoid sinus


—

. ^ .'

^0^I^F

.2

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^

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1

Thalamostriate vein


Transverse sinus

Bulb of the internal jugular vein

Occipital sinus



Vein of Galen

Superior choroidal vein


Thalannic vein

Basal vein of Rosenthal (posterior mesencephalic vein)

Lateral mesencephalic vein

Anterior pontomesencephalic venous plexus

Petrosal vein

Transverse pontine vein

Superior petrosal sinus -

Inferior petrosal sinus -

Sigmoid sinus -

Internal jugular vein -

Superior vermian vein

Straight sinus

Precentral cerebellar vein

Transverse sinus



Inferior vermian vein

Cerebellar hemispheric vein


Superior superficial cortical veins ^

Thalamostriate vein

Anterior caudate vein

Septal vein


Superior petrosal sinus




Vein of Galen

- Straight sinus

Veinof Labbe


Thalamostriate vein


Sylvian vein


Inferior ophthalmic vein

Cavernous sinus

Inferior petrosal sinus


Vein of Galen

Superior petrosal sinus


Intercavernous sinus

Superficial petrosal sinus

f^ » • • . ^

Cavernous sinus

^ Transverse sinus

Inferior petrosal sinus

Sigmoid sinus



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Anterior intercavernous sinus

Cavernous sinus i ^

u 1/

Inferior petrosal sinus —'


f PI segment

P2 segment

P3 segment

P4 segment

4r i'

/

t i

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r Internal carotid artery

Basilar artery

/

. Bibliography 353

Bibliography

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Di Salle R, Duvernoy H., Rabischong R, Scarabino T., Salvo-lini U., Atlas of Morphology and Functional Anatomy of the Brain. Springer-Verlag, Berlin, 2005.

Duvernoy H.M., The Human Brain: Surface, Blood Supply, and Three Dimensional Sectional Anatomy, 2" edition. Springer, Vienna, 1999.

Duvernoy H.M., The Human Hippocampus, 2" edition. Springer-Verlag, Heidelberg, 1998:

Gallucci M., Gagliardo O., Splendiani A., De Amicis R., La loggia cavernosa: anatomia neuroradiologica normale. Ri-vista di Neuroradiologia 13:367-73,2000.

Gallucci M., Sparvoli L., Patologia delVosso temporale. In: Dal Pozzo G., Compendio di Risonanza Magnetica, Cranio e Rachide. UTET, Torino, 2001:807-836.

Gallucci M., Splendiani A., Masciocchi C., Spine and spinal cord: Neuroradiological functional anatomy. Rivista di Neuroradiologia 11:293-304,1998.

Herrero, Barcia C., Navarro J.M., Functional anatomy of thalamus and basal ganglia. Child's Nerv. Syst. 18:386-404, 2002.

Krayenbuhl H., Huber P., Yasargil M.G., Cerebral angiography, 2" completely revised edition. Thieme-Verlag, Stuttgart, 1982.

Lasjaunias P.L., Berenstein A., Surgical Neuroangiography: Functional Vascular Anatomy of Brain, Spinal Cord and Spine. Springer-Verlag, Berlin, 1991.

Mazzucato R, Anatomia radiologica tecnica e metodologia. Propedeutiche alia diagnostica mediante immagini. Ed. Piccin, Torino, 1997.

Nieuwenhuys R., Voogd J., van Huijzen C, The human central nervous system. Springer-Verlag, Berlin, 1988.

Nolte J., The Human Brain. An introduction to its functional anatomy, 4 ^ edition. Mosby, St. Louis, MO, 1999.

Osborn A.G., Cerebral Angiography, 2" edition. Lippincott Williams and Wilkins, Philadelphia, 1999.

Osborn A.G., Diagnostic Neuroradiology. Mosby-Year Book, St. Louis, MO, 1994.

Perugini S., Ghirlanda S., Manfre L., Gallucci M., Castrucci M., Rocche petrose, in: Compendio di Tomografia compu-terizzata e TC spirale. Ed. Dal Pozzo G., 1999:263-285.

Talairach J., Co-Planar Stereotactic Atlas of the Human Brain. Thieme Verlag, Stuttgart, 1988.

Tamraz J.C, Comair Y.G., Atlas of Regional Anatomy of the Brain Using MRI with Functional Correlations. Springer-Verlag, Berlin, 2000.

Truwitt C.L., Lempert T.E., High resolution atlas of cranial neuroanatomy. Lippincott Williams and Wilkins, Baltimore, 1994.

Subject Index . Subject Index 355

Adenohypophysis 280,281,283,284 Aditus ad antrum 178,179 Amnion's horn 263,270 Ampulla, - posterior 176,196 - superior 171,178,196 Amygdala 228,229,235,236,271,276 Antrum 179,180,192,193 Aqueduct, - cochlear 174,175 - vestibular 162,177,180,195 Area 1,2,3,208-210 - Broca's speech (44) 253,254 - entorhinal 51,52,64,115,266,269 - hand motor 211,212 - marginal 253 - nasal 119 - premotor(6,8)208-210 - primary olfactory 116 - second olfactory 116 - septal (see also septal nuclei) 273 - striata 119 - subcallosal 263 - temporal 119 - vestibular cortical 168,170 - Wernicke's speech 253,254 Artery/ies, - angular 301 - anterior cerebral 49,70,226,227,319,326,334 - - bifurcation of 302,303 - - post-communicating segment, A2 302-304,313

pre-communicating segment, Al 285,302-304,307,308, 310,313

- anterior choroidal 300,320 - anterior communicating 303,306,310 - anterior deep temporal 299 - anterior internal frontal 301 - anterior parietal 301 - anterior temporal 314

anterior thalamoperforating 317,320 antero-inferior cerebellar 145,312,314,315,317,319,328, 329 basilar 52,66,67,103,106,107,122,287,290,304,306,311, 315,327 calcarine 315 callosomarginal 303 descending (greater) palatine 299 external carotid 299 fronto-opercular 301 frontopolar 301 inferior internal parietal 301 inferior temporal 315,316 infraorbital 299 internal carotid 50,65,120,227,300,304,310 - cavernous segment, C4 301,303 - cervical segment, CI 301-303 - clinoid segment, C5 301-303 - communicating segment, C7 285,301,302 - in carotid canal 184 - lacerum segment, C3 301,303 - ophthalmic segment, C6 301,303 - petrous segment, C2 301-303 lateral lenticulostriate 303 lateral-posterior choroidal 317 masseteric 299 maxillary 299 medial-posterior choroidal 317 middle cerebral 50,69,139,227,319,326,334 - insular segment, M2 303,304 - opercular segment, M3 303,304 - post-bifurcation Ml segment 303-305,307,308 - pre-bifurcation Ml segment 285,302-305,308 middle deep temporal 299 middle internal frontal 301 middle meningeal 153,299 occipital 299 ophthalmic 120,300,301 orbitofrontal 301

- parieto-occipital 315-317 - pericallosal 301-303 - posterior cerebral 139,142,287,305,319,329,334 - - ambiens segment, P2 304,307,314,315 - - calcarine segment, P4 305,310,315 - - horizontal or pre-communicating segment, PI 304,306 - - pre-communicating segment, PI 110,315 - - quadrigeminal segment, P3 304,307,311,315 - posterior communicating 145,300,304,308-310 - posterior internal frontal 301 - posterior parietal 301 - posterior temporal 301,311 - postero-inferior cerebellar 315,319,328,329 - prefrontal 301 - prerolandic 301 - rolandic 301 - spheno-palatine 299 - superficial temporal 299 - superior cerebellar 305,308-310,312,315,317,319,329 - superior internal parietal 301 - superior posterior alveolar 299 - thalamoperforating 316 - transverse facial 299 - vertebral 101,102,316,328 Asterion 8 Atlanto-axial, - articular space 7 Atlas 20 - lateral mass of 3,7,197 - peduncle of 7 Axis, - lateral mass of 7 - odontoid process of 7,20,22 - spinous process of 7

Body - ciliary 128 - amygdaloid 115 - lateral geniculate 111,119,257

356 Subject Index

- mammillary 44,69,111,257,263 - medial geniculate 164,166,220 - trapezoid 164,165,260 Bone, - ethmoid 11,15,17 - - cribriform plate of 117 - - lamina papyracea of 127 - - perpendicular lamina of 18 - frontal 11,15,17,19 - - orbital aspect 127 - hyoid 5,19,21 - lacrimal 11,12 - malar 5 - maxillary 11,13,15 - - frontal process of 18,127 - nasal 5,11,13,15,19,21 - occipital 14,16,20 - palatine 15 - - orbital process of 12 - parietal 13-15,17,19 - petrous - - superior border of 6 - sphenoid 12,13,15,16 - - greater wing of 18,19,23,127

lesser wing of 3,22,278,279 - temporal 13,15-18 - - petrous pyramid of 6,22,23 - vomer 15 - zygomatic 6,11,12,18,19,127 Brachium, - conjunctivum inferior 164,166 - conjunctivum superior 124 Bregma 8 Bulb - olfactory 45,115,118,133 - jugular 190,346,347

Calcaravis 71 Canal - carotid 120,174 - carotid (horizontal portion) 175,176 - carotid (vertical portion) 173 - Dorello's 142

- external auditory 171,173,174,189,193,279 - facial 189 - - first segment (horizontal, labyrinthine) of 181,188 - - second segment (horizontal, tympanic) of 190,192 - - third segment (vertical, mastoid) of 173,174,176,196,197 - hypoglossal 201 - inferior vestibular 195 - internal auditory 171,179,180,182,193,278 - lateral semicircular 163,171,178,180,191 - of stapedial muscle 176 - of tensor tympani muscle 178,184,185 - optic 23,120 - posterior semicircular 163,171,175,176,178,180 - superior semicircular 163,171,183,190,191 - superior vestibular 194 - vertical semicircular 162 Capsule - extreme 227 - external 227 - internal

anterior limb of 219,225,226 posterior limb of 208,219

Cave, Meckel's 22 Centrum semiovale 78 Cerebellum 108 Cerebral aqueduct of Sylvius 55,67,108, 232,291,293,296 Chorda tympani 159 Choroid 128 Cistern - ambiens 291 - cerebello-medullar is (see also cisterna magna) 290,293 - chiasmatic 293 - insular (see also cistern of sylvian fissure) 291 - interpeduncular 110,293,294 - interhemispheric 292 - of sylvian fissure (see also insular cistern) 291 - of the cerebello-pontine angle 290 - of the great cerebral vein (of Galen) 59,291-293 - of the lamina terminalis 293 - of transverse fissure (see also cistern of velum interposi-

tum) 56,293 - of velum interpositum (see also cistern of transverse fis

sure) 293

- pericallosal 293 - pontine 290,293 - posterior basal 290 - quadrigeminal (see also tectal cistern) 291-294 - superior cerebellar 291,293 - suprasellar 282 - tectal (see also quadrigeminal cistern) 291,293,294 Cisterna, - magna (see also cerebello-medullaris cistern) 290,293 Claustrum 217,230,238-240 Clivus 278,279 Cochlea 163,178,189,190 - apical turn 177 - basal turn 162,171,175,177,191 - middle turn 162,177,186 - spiral lamina of the 180 - upper turn 162,186 Colliculi (see also quadrigeminal tubercle or quadrigeminal

plate or tectum of midbrain) 224 Colliculus, - facial 105 - inferior 56,68,109,166,233,258 - superior 43,55,56,70,111,233,257 Commissure, - anterior 38,42,44,71,115,223,224,228,237,273,275 - habenular 115 - posterior 44,55,71,224,237 Condyle, occipital 197 Cornea 128,137 Corona radiata 208,214,241 Corpus callosum 41,275 - body of 44,48 - genu of 42,43,47, 73, 75 - isthmus of 43,54 - radiation of 119 - rostrum of 44 - splenium of 42,43,56,57,72,75 - sulcus of 48,57 Cortex - premotor (area 6) 205 - premotor (area 8) 205 - primary motor (area 4) 205,208,210 - retrosplenial 71

. Subject Index 357

Crista galli 22,117 Culmen 92,96,99,106,107 Cuneus(O6)41,42,60,69

Declive 92 Diploe 4 Dorsum sellae 22 Duct, endolymphatic 181

Ear, - external 171 - inner 171 - middle 171

Falciform crest 161,190,191 Fasciculus, - dorsal longitudinal 257,259 - gracile 243,262 - inferior occipitofrontalis 276 - medial longitudinal 168,259 260,262 - medial telencephalic 115,263 - superior longitudinal 276 - superior occipitofrontalis 276 Fasciola cinerea 263 Fibers, - arcuate 243 - thalamo-cortical 245 - zonular 128 Fissure, - antero-superior (primary fissure) 96 - calcarine 40,61,62,68,119,122,124 - cavernous 278 - central of Rolando 25,26 - choroidal 263 - horizontal 87,90,93,97 - inferior orbital 127 - interhemispheric 25 - lateral of Sylvius 26,31-33,35,47,48,69,73,75 - longitudinal 45 - parieto-occipital 26,39,40,42,60 - post-central 93,95,105,106 - postero-superior 98 - postpyramidal (secondary fissure) 95,96

- prepyramidal 94,97 - sphenoidal 279 - superior anterior 92 - superior orbital 23,127,146,278 - temporo-occipital 68 Flocculus 88,93 Folium 92 Foramen - infraorbital 18 - interventricular (of Monro) 289,292,296

choroid tela of the 295 - jugular 22,200 - lacerum 278 - mental 18 - occipital 6,22 - ofLuschka 103,200 - ofMagendie 101,200,290,293 - ovale 120,155,174,278 - rotundum 3,6,22,23,155,279 - spinosum 22,155,174 - stylomastoid 159,196,197 Fornix 43,223,231,237,240,271,272 - body 52,72,74,276 - column 43,51,69,71,228,229,276 - crus 41,42,73,263 Fossa, - geniculate 180,181 - jugular 173 - middle cranial 182 - posterior cranial 182 - pterygopalatine 155 Fourth ventricle 63,94,101,289 - choroid plexus 290 - choroid tela of 293,294 - lateral foramen of Luschka 289 - lateral recess 289,290,294 - median sulcus of 56 - midline foramen of Magendie 289

Ganglion, - gasserian 63,145,150,152 - sensory 214 Glabella 9

Gland, - lacrimal 129,132 - pineal 44,56,94,295 - pituitary 50 Globus pallidus, - pars lateralis 219,230,237-239 - parsmedialis 219,230,237,238 Gnathion 9 Gonion 8 Gray bridges, caudate-lenticular 232 Groove, - carotid 22,279 - chiasmatic 23,279 - infraorbital 127 - of greater petrosal nerve 179,185 - olfactory 117 - superior sagittal sinus 23 Gyrus/i, - ambiens (see also uncus) 51,52,115,136 - angular 31,34,35,59,62,78 - anterior orbital 38,39,45,71 - anterior transverse temporal 32,54 - ascending frontal (Fa) 25 - ascending parietal (Pa) 25 - central 35 - cingulate 41,42,46,51,56,71,72,273 - dentatum 263,270,273 - descendens (Ecker) 39,40,65,67,122 - diagonal 263 - fasciolar 263,273 - fourth occipital (04) 36,62 - frontomarginal 34,35,39,70,72,137 - frontopolar 42 - fusiform (04) 60,66 - fusiform (14)35,51,52,64 - inferior frontal (F3) 25,26,47,133 - - pars opercular is (op) 26,31,48,49,72,73,251 - - pars orbitalis (o) 26,31,46,72 - - pars triangularis (t) 26,31,46,47,73 - inferior frontopolar 36,39,137 - inferior lingual (05) 58,59 - inferior occipital (03) 35,38,60,62,65,67 - inferior parietal (P2) 25,59

358 Subject Index

- inferior temporal (T3) 26,31,35,47,48,52,64,66 - insular long 34,35 - insular short 34,35 - intraparietal 34 - lateral orbital 33-35,45,71,72 - lingual (05) 39,68 - long insular 51 - medial orbital 39,45,68,70 - middle frontal (F2) 25,33,34,46,47,53,73,75,133,208-210 - middle occipital (02) 32,34,36,38,60-62,69,75 - middle orbital 38 - middle temporal (T2) 26,31,35,47,49,52,64,66 - nuclei (see also paraterminal gyrus) 136 - orbital 27 - parahippocampal (T5) 37,39,53,64,66,67,267 - paraterminal (see also gyrus nuclei) 43,44,50,136 - postcentral (Pa, ascending parietal gyrus) 31,35,36,40,54,

73,74,208,210,245,246 - posterior orbital 36-39,47,70,71 - posterior transverse temporal 54 - precentral (Fa, ascending frontal gyrus) 31, 35, 36, 40,

50-52,54,74,80,208-210 - rectus 27,41,42,46,47,68,134 - semilunar 52,115 - short insular 48,49,51 - subcallosal 44,70-72 - subcentral 32,33,51,52 - superior frontal (Fl) 25,36,37,40,46,47,53,71,73,79,208-210 - superior frontopolar 36,39,137 - superior lingual (05) 122 - superior occipital (01) 37,38,71,73 - superior parietal (PI) 25,37,59,60,80,84,246 - superior temporal (Tl) 26,31,35,47,48,52,54,64,66 - supramarginal 31,33,55,56,58,76 - transverse temporal (of Heschl) 73,164,166 - temporo-occipital 66

Hard palate 5 Hippocampus 36,271,273 - body 264 - fimbria 273 - head 37,40,54,66,67,264 - queue 265

- tail 39,40,57,71,72,56 Hypoglossal canal 22 Hypothalamic-pituitary, - stalk 281,282,284 Hypothalamus 228,229,237 Hypotympanum 172,173,185

Incisure, - lateral temporo-occipital 31-33 - medial temporo-occipital (see also collateral sulcus) 36 - supraorbital 18 Incus, - body 171,178,187,188 - longcrus 171,175,177 - short crus 171,177,178,192 Indusium griseum 263,273 Inhibitory interneuron 215 Inion (see also external occipital protuberance) 8 Insula 36,71,74,251 Isthmus 41,42,57

Joint, - atlanto-axial 3 - atlanto-occipital 3 - incudo-malleolar 179 - incudostapedial 176 - temporo-mandibular 175,184

Labyrinth 171 Lambda 8 Lamina, - quadrilateral 279 - terminalis 295,296 Lateral ventricle 43 - atrium of 36,37,40,57,72,73,75 - body of 53 - choroid plexus 57,74,291,292 - - glomus of 291,292 - choroid tela 294,296 - frontal horn of 41,46,47,49, 72, 73, 74,289,292 - occipital horn of 58,59,70,289,291 - temporal horn of 35,36,52,53,66,67,69,289,291 - trigone 289,291,292

Lemniscus, - lateral 164,165 - medial 105,243,244,258-262 - medialis 214 Lens 128,137 Limen insulae 34,35 Line, - auricular vertical 10 - Frankfurt or Wirchov's line 10 - innominate 3 - orbito-meatal 10 - superior horizontal 10 Lingula (vermis) 91 Lobe, - frontal 25,45 - occipital 26 - parietal 26,57 - piriform 64,269 - temporal 26,27 Lobule, - biventral 87,89,93,97,101 - inferior semilunar 87,93,94,100,102 - paracentral 57,81,82,84,210 - quadrangular 87,93 - simplex 87,88,93,100,104 - superior semilunar 87,94,100 Locus coeruleus 92

Malleus 187 - body of 178 - head of 171,177,189,190 - manubrium of 171,174,175,189 Mandible 5,11,13,15 - angle of 6,20 - condyle 3 - horizontal ramus of 7 - vertical ramus of 7,18 Massa intermedia 238 Mastoid 182,196,197 - air cell 171,173,174 Meatus, - external acoustic 8,19 - internal acoustic 2122

. Subject Index 359

Medulla oblongata 93,101 Membrane - tympanic 187,173,188,189 Midbrain - tectum of 93,109 Modiolus 162,179,187 Muscle, - inferior rectus 45,133,134,139 - lateral rectus 45,129,134 - levator palpebrae superioris 131,134,139 - medial rectus 45,129,134 - superior oblique 130,134 - - trochlea of 130 - superior rectus 45,131,134,139 - tensor tympani 186

Nasal septum 6 Nasion 9 Nerve, - abducens VI 284 - - cavernous portion 142 - - nucleus of 141 - accessory 200,202 - cochlear 164 - facial 260 - - cisternal segment 160 - - genu of 157 - - geniculum of 186 - - internal genu of 260 - - intracanalicular segment 160 - - petrous segment 160 - glossopharyngeal 200,202 - great petrosal 159 - hypoglossal 201,202 - inferior vestibular 160 ~ intermedins 159 - mandibular (V3) 145 - maxillary (V2) 145,284 - oculomotor (III) 146,284 - - accessory nucleus of 141 - - cavernous portion 142 - - nucleus of 141

- ophthalmic (VI) 145,146,284 - optic 41,43,45,67,119,120,133,134

infraorbital portion 121 - posterior auricular 159 - superior vestibular 161 - to stapedius muscle 159 - trigeminal - - cisternal portion of 148,149 - - mesencephalic nucleus 147 - - mesencephaHc tract 147 - - motor nucleus of 147

motor root of 147 - - sensory nucleus 147 - - sensory root of 147 - - spinal nucleus 147 - - spinal tract 147 - trigeminal (V) 145 - trochlear (IV) 146,284 - - nucleus of 141 - vagus (X) 200,202 - vestibular 168 Neurohypophysis 281,283 Nodulus 92,96,104 Nuclei, - cochlear 157,165 - medial and lateral vestibular 260 - septal (see also gyrus paraterminal, septal area) 43, 273 - vestibular 157 Nucleus, - abducent 260 - accessory 115 - accumbens 41,42,226 - ambiguus 199,261 - anterior amygdaloid 115,263 - basal amygdaloid 218,219,263 - caudate 219 - - body of 200,228,230 - - head of 205,220-222,225,237-241 - - tail of 205,232,233,237,238,241 - cortical amygdaloid 219, 263 - cuneate 244,261,262 - dentate 90,96,97,104 - dorsal cochlear 164,260

- dorsal vagal 199,261,262 - emboliform 91,96 - facial 260 - fastigial 91,96 - globose 91 - gracile 243,244,262 - habenular 72,115,238,263 - hypoglossal 261,262 - inferior olivary 93,101 - inferior vestibular 168,260,261 - interstitial 168 - lateral amygdaloid 218 - lateral of amygdala 263 - lateral vestibular (Deiters') 168,169 - medial cuneate 243 - medial superior olivary 164 - medial vestibular 168 - mesencephalic - - of trigeminal nerve 258 - - motor trigeminal 259 - of lateral lemniscus 164 - of nerve glossopharyngeal 199 - of nerve hypoglossal 199 - of oculomotor nerve 168,257 - of spinal root of accessory nerve 199 - of trapezoid body 164 - of trochlear nerve 168,258 - oval 249 - red 91,111,221231,257,263 - salivatory 157,199 - solitary 250,261,262 - - pars gustatoria of 249 - spinal - - of trigeminal nerve 260-262 - superior lateral olivary 164 - superior vestibular 168,259,260 - thalamic - - anterior 223,238-240

centromedian 221-223,237-239 - - lateral dorsal 221-223,240

lateral posterior 220,238,240 - - medial 115 - - mediodorsal 221-223,238,239

360 Subject Index

ventral anterior 222,223 - - ventral intermediate 170 - - ventral lateral 220,221,230,238,239,240 ~ - ventral posterolateral 220,237,238,239,243 - - ventral posteromedial 237,238,249,251 - trigeminal 259 - ventral cochlear 164,260

Obex 92,289 Olive 200,261,262 Operculum, - central (see also rolandic operculum) 50 - frontal 48,49 - parietal 55 - rolandic (see also central operculum) 50,52 Optic, - bulb 119 - canal 278,279 - chiasm 43,44,50,68,119,277,280,295 - nerve 139,226,277 - tract 51,277 Orbit 6 Orbital, - fat 128 - floor 6 Ossicular chain 171

Peduncle, - inferior cerebellar 94,164,260,261 - middle cerebellar 89,93,104,105,106,260 - superior cerebellar 94,106,257,258,259 Periarcheo cortex 272 Periorbit 128 Petrous pyramid 6,22,23 - apex of 278 Pineal, body 224 Pituitary - gland 137 - stalk 50,123,277,295 Planum, - polare 164 - sphenoidal-ethmoid 5 - temporale 56

Plate, - quadrigeminal (see also quadrigeminal tubercle or tectum

of midbrain or colliculi) 93,224 Plexus venous, - anterior ponto-mesencephalic 348 Pogonion 9 Pons 93,104,107,161 Porion 8 Precuneus (PI) 60,74,79 Process, - alveolar 5,18 - anterior clinoid 4,21,22,23,120,278,279 - posterior clinoid 4,21,23,278,279 - mastoid 7,19 - palatine 21 - pterygoid

hook of 21 - - lamina of 21 - styloid 20,195,196 Promontory 191,192 Protuberance, - external occipital (see also inion) 4,8,20 - frontal 18 - mental 18 Pterion 8 Pulvinar 219,221,238,239 Putamen 219,237,240 Pyramid 102 - of medulla 101,103 Pyramidal, decussation 205,262 Pyramis 92

Radiation, - acoustic 164,166 - optic 71,124 - - occipital genu 119 - - temporal genu 119 Recess, - infundibular 289,295 - optic 289 - parabrachial 106,107 - pineal 289 - suprapineal 289

Retinic ganglion cells 121

Saccule 162 Sclera 128 Scutum 188,189,190 Sella turcica 21,278,279 - floor 4,22 Sensibility, - epicritic 215 - pain and temperature 215 - protopathic 215 - propioceptive 215 Septum, - jugulohypotympanicum 173,187,190 - Korner's 193 - pellucidum 44,49,50,73,273 - verum 263 Sinus, - cavernous 142,280,286,287 - ethmoidal 6 - - cells of 3 - frontal 5,6 - inferior petrosal 348,350 - inferior sagittal 295,296,346,349,350 - intercavernous 351 - intercavernous anterior 352 - maxillary 6 - occipital 347 - sigmoid 173,197,341,342,344,347,348 - sphenoid 4,128,283,280,284 - straight 70,297, 343,348 - superior petrosal 348,350 - superior sagittal 45,70,76,81,292,341,348,349 - transverse 341-343,348,351 - tympani 176,194 Siphon, internal carotid 151,277,280,284 Space, - Prussak 189 Spina, - jugular 173 Spinal cord 92,93 Spine, - anterior nasal 9,19,21

. Subject Index 3 6 1

Stapes 171,177,190,192 Stria, - dorsal acoustic 164 - lateral olfactory 115 - medial olfactory 115 - meduUaris 239 - sagittal 119 - terminalis 115,263 Subiculum 194,263,267 Substance, - anterior perforated 51,115,118,228,273,296 Substantia nigra 91,230,231 - pars compacta 257 - pars reticulata 257 Sulcus, - anterior calcarine 59 - anterior temporal 70 - arcuate (see also transverse orbital sulcus) 45 - calcarine 73 - central 31,33,36,40,54,73,74,77 - central insular 34,35 - cingulate 40,42,46,51,56,72,77,81 - circular insular 34,35,48,49,51,52 - collateral (see also medial occipito-temporal incisure or

sulcus) 36,39,51,52,60,64,65,66 - frontal middle 49 - frontomarginal 37,39,72,137 - inferior frontal 33,45,47 - inferior occipital 61,62 - inferior precentral 74,75,77 - inferior temporal 32,52 - intermedins primus (Jensen) 31,77 - intraoccipital 76 - intraparietal 36,55,56,62,77 - lateral occipital 32,33,61 - lateral orbital 33 - lateral temporo-occipital 52,54,58,60 - lingual 59,70 - lunate 36 - middle frontal 77 - olfactory 41,45,47,68 - orbital 46 - paracentral 82,83

- parieto-occipital 71 - ponto-medullar 91 - ponto-mesencephalic 92 - postcentral 32 - posterior transverse collateral 35,61,67,68 - precentral 32 - retrocalcarine 68,124 - subparietal 44,77 - superior calcarine 58 - superior frontal 37,39,46,77 - superior postcentral 58,81,82,84 - superior precentral 38,40 - superior temporal 32,48,52,58,59,62,66,67,70,77 - supraorbital 42,43 - transverse occipital 37 - transverse orbital (see also arcuate sulcus) 45 - transverse parietal 41,43 Suture, - coronal 19 - fronto-zygomatic 6,18 - intermaxillary 18 - lambdoid 4,19,20 - maxillary-nasal 18 - maxillo-lacrimal 18 - occipital-mastoid 20 - petro-clival 155 - sagittal 3,18 - spheno-occipital 23 System, - vertebrobasilar 315

Table, - inner 4 - outer 4 Tarsal plate, of the eyelid 128 Tectum, - of midbrain (see also quadrigeminal tubercle or quadri-

geminal plate or colliculi) 224 Tegmen tympani 189 Temporal, - squama 19 Tendon, - of tensor tympani muscle 187,188

Tentorium, - border of 286 Territories, - vascular 319 Thalamus 224 Third ventricle 53,71,280,293 - chiasmatic recess 282 - choroid tela of 296 - infundibular recess of 111,122,282,291 - optic recess of 291 - pineal recess of 295 - suprapineal recess of 295 Tonsil 101 - of cerebellum 90,94 Torcular Herophili (sinus confluence) 341,347,348 Tract, - anterior spinocerebellar 262 - corticospinal 206,208 - dorsal trigeminus-thalamic 249,250 - frontopontine 205,257 - lateral olfactory 116 - lateral vestibulospinal 169 - mammillothalamic 237,238,276 - medial vestibulospinal 169 - occitopontine 205 - olfactory 115,118 - optic 42,69,111,257 - - lateral root 119 - - medial root 119 - parietopontine 205 - parietotemporopontine 257 - pontocerebellar 258,260 - posterior spinocerebellar 262 - pyramidal 104,106,205,257,262 - spino-thalamic 257 - temporopontine 205 - vestibulothalamic 169 Tractus, - pyramidalis anterior 214 - pyramidalis lateralis 214 Trigone, olfactory 68,69,131 Tube, auditory (eustachian) 174,175,184 Tuber 92

362 Subject Index

Tubercle, Vertex 8 - quadrigeminal (see also quadrigeminal plate or tectum Vestibulus 171,178,179,191-193

of midbrain or coUiculi) 224 Vitreous 137 Tuberculum sellae 23,279 Tympanic cavity, 171,175 Window, - epitympanum 172 - oval 171,192 - hypotympanum 172 - round 175,194 - mesotympanum 172

U-fibers 275 Uncus (see also gyrus ambiens) 50,136 - apex 266 Utricle 162 Utriculus 194 Uvula 92,96,97,101

Vasal imprint 4 Vein, - anterior caudate 349 - basal of Rosenthal 344,348 - cerebellar hemispheric 348 - choroid 292 - cortical 342 - hemispheric cerebellar 347 - inferior ophthalmic 350 - inferior vermian 347,348 - internal cerebral 55,73,74,292,295,296,344,348 - internal jugular 341,347 - lateral mesencephaHc 348 - middle cerebral 344,345 - of Galen 224,292,295,296,344,345,348 - ofLabbe 343,344 - ofTrolard 343 - petrosal 347,348 - posterior mesencephalic (see also basal vein of Rosenthal) 348 - precentral cerebellar 348 - septal 349 - superior choroidal 348 - superior ophthalmic 130,139,350 - thalamic 348 - thalamostriate 347 - transverse pontine 348 Velum, superior medullary 92

13675335 radio-graphic-atlas-of-skull-and-brain-anatomy-20061120-3540341900-massimo-gallucci-silvia

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