brainstem i neuroscience 2005. lecture overview definition of brainstem brief gross orientation...
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BRAINSTEM I
Neuroscience 2005
LECTURE OVERVIEW• Definition of Brainstem
• Brief Gross Orientation
• Brief Cross Sectional Anatomy Orientation
• Correlation of Gross and Cross Sectional Anatomy
• Composite List of Brainstem Structures
• Cranial Nerves (CN’s)– Introduction– Nucleus vs. Ganglion– Organization / Classification Based on Embryology
» Spinal Cord vs. Brainstem» Skeletal mm: Branchial Arch vs. Somite Myotome» Correlation of Location and Function of CN’s
DIVISIONS of the BRAINSTEM
• Midbrain• Pons• Medulla
(Terms “upper” and “lower” sometimes used)
LOCATION of BRAINSTEM
• Cranial Cavity– Begins caudally at
FORAMEN MAGNUM
– Mostly infratentorial
• CNS– Between spinal cord and
diencephalon
Carpenter, Core Text of Neuroanatomy, 1991
Brainstem in situ
Nolte Text, p. 263
Grant’s Atlas of Anatomy
Median Saggital Plane
Nolte Text, p. 267
Haines AtlasHaines Atlas
Haines Atlas, fig. 6-2
SERIAL SECTIONS
Haines Atlas
CLINCAL IMAGING vs. ANATOMYWHICH WAY IS UP?
VENTRAL DORSAL
Haines Atlas
CLASSICAL REPRESENTATIVE SECTIONS
MEDULLA
PONS
MIDBRAIN
Haines Atlas
Nolte Fig. 11-5
Nolte Fig. 11-6
Brainstem Structures:
• Name• Location• Function• Dev. Divisions
MesenMetenMyelen
Nolte Fig. 15-3
Cranial Nerves
Medulla 9 - 12
Pons 5 - 8
Midbrain 3 & 4
Diencephalon 2
Telencephalon 1 (not pictured)
Spinal Cord 11
Cranial Nerves (CN’s)• HEAD AND NECK INNERVATION
• Components of CN’s:1) Sensory2) Special sensory3) Motor (2 embryological types of skeletal mm)4) Autonomic Motor:
Parasympathetics (sm. mm, glds) - preganglionic - head to the transverse colon - where do the sympathetics to the head originate?
• Neurons of origin in:- NUCLEI- GANGLIA
• Clinical relevance: - localization of lesions - extent of damage / prognosis - difficult to treat
CRANIAL NERVENUCLEUS vs. GANGLION
• WITHIN CNS• CLUSTER OF NEURONS• NOT PSEUDOUNIPOLAR*• SENSORY OR MOTOR
• OUTSIDE OF CNS• CLUSTER OF NEURONS• PSEUDOUNIPOLAR• SENSORY
*except mesencephalic nucleus of V
Carpenter, Core Text of Neuroanatomy, 1991
SENSORY GANGLIA of CRANIAL NERVES
Langman’s EmbryologyCarpenter, Core Text of Neuroanatomy, 1991
Cranial Nerve Nuclei
“WORM DIAGRAMS”
NOLTE HAINES ATLAS
CLASSIFICATION OF CRANIAL NERVES
• Based on:A. Function
• Motor – Somatic (skel. mm)– Visceral (sm. & card. mm & spec. skel. mm)
• Sensory• Special Sensory
B. Embryologically Derived Location• Alar plate = sensory (lateral)• Basal plate = motor (medial)
SENSORY and MOTORORGANIZATION
Embryonic CNS Spinal Cord Brainstem
Langman’s Embryology
SPINAL CORD (body) BRAINSTEM (head*)
Motoneurons (EFF) :– somatic motor (skel. mm)– visceral motor (sm. & card. mm.,
glands)
Sensory neurons (AFF):– somatic sensory (skin, muscle,
muc. mem., bone, and joint receptors)
– visceral sensory (viscera)
Motoneurons (EFF):– somatic motor (skel. mm)– visceral motor (sm. &card.
mm., glands)– branchial motor (skel. mm)
Sensory neurons (AFF):– somatic sensory ( skin,
muscle., muc. mem., bone, and joint receptors)
– visceral sensory (viscera)– special visceral (taste, smell)– special somatic (eye, ear)
*vagus and accessory nn. also to body
Somatic vs. Branchiomeric Skeletal Muscle
• Somatic: from the myotomes (part of somites)– extraocular mm = CN III, IV, VI– tongue mm = CN XII
• Branchial: from branchial arch* musculature – mm of mastication = CN V– mm of facial expression = CN VII– mm of the pharynx and larynx = CN’s IX, X, XI (ambiguus)
*also referred to as “pharyngeal arch”
Pharyngeal Arches
Langman’s Embryology
• Pharyngeal = Visceral so skel. musc. from arches is a “special” kind of “visceral” muscle (SVE)• The term Pharyngeal Arch is used interchangeably with Branchial Arch• BRANCHIAL motor = SVE
BRANCHIAL ARCHES (PHARYNGEAL ARCHES)
1st = V musc. mast., ant. belly dig., mylohy., tensor tym., tensor palat.
2nd = VII musc. facial expr., stapedius, post. belly dig., stylohyoid, auricular
3rd = IX stylopharyngeus
4th = X Sup. Laryngeal Br. = cricothyroid, levator palat., pharyng. constr. ( 6th arch supplied by Recurrent Laryngeal Br. = intrinsic laryn. mm; also CN XI)
Langman’s Embryology
Langman’s Embryology
Gilman & Winans-Newman
Nolte Text, p. 376
Nolte Fig. 12-1
Special SensorySomatic SensoryVisceral Sensory
Visceral motorBranchial motorSomatic motor
Haines Atlas
G 5, 7, 9, 10 = skin + mucous mem. (prop. 3, 4, 6, 12)
SS 2, 8 = eye + ear
AG 9, 10 = int. organs
VS 7, 9, 10, 1 = taste, olf.
S G 12, 3, 4, 6 = tongue + eye mm (myotomes)E
G 3, 7, 9, 10 = parasymp.V
S 5, 7 ambig. = branchial mm