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The Axial Skeleton

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The Axial Skeleton. This structure is composed of 27 bones and is formed from cranial and facial bones. The cranial bones protect the brain and allow attachment for the neck and head muscles. The Skull. The facial bone have several functions: Form the frame work for the face - PowerPoint PPT Presentation

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Page 1: The Axial Skeleton

The Axial Skeleton

Page 2: The Axial Skeleton

Copyright © 2010 Pearson Education, Inc.

The SkullThis structure is composed of 27 bones and is formed from cranial and facial bones.

The cranial bones protect the brain and allow attachment for the neck and head muscles.

Page 3: The Axial Skeleton

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The SkullThe facial bone have several functions:• Form the frame work for the face• Contain cavities for the senses• Provided openings for air and food• Secure the teeth• Anchor the facial muscles

Page 4: The Axial Skeleton

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Sutures• With the exception of the mandible all bones of the adult skull are interlocked by joints called sutures.• The major sutures are the

– Coronal– Sagittal– Squamous– Lambdoid

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Figure 7.2a The skull: Cranial and facial divisions and fossae.

Bones of cranium (cranial vault)

Lambdoidsuture

Facialbones

Squamoussuture

(a) Cranial and facial divisions of the skull

Coronalsuture

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The FloorThe floor is divided into the

anterior , middle and posterior fossae

Page 7: The Axial Skeleton

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Figure 7.2b The skull: Cranial and facial divisons and fossae.

Anterior cranialfossa

Middle cranialfossa

Posterior cranialfossa

(b) Superior view of the cranial fossae

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External Features

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Anterior and Posterior Aspects of the Skull

• Supraorbital margin is a throw back to our simian cousins

• For us it supports our eye brows

• The Supraorbital foramen is the path for the supraorbital nerve and vessels

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Anterior and Posterior Aspects

The superior nuchal and inferior nuchal lines serve as attachment points for muscles and ligaments.

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Figure 7.5a Bones of the lateral aspect of the skull, external and internal views.

Coronal suture Frontal bone

Sphenoid bone(greater wing)

Ethmoid bone

Lacrimal bone

Lacrimal fossa

Nasal bone

Zygomaticbone Maxilla

Alveolarmargins

MandibleMental foramen

Parietal bone

Lambdoidsuture

SquamoussutureOccipitalbone

OccipitomastoidsutureExternal acousticmeatusMastoid processStyloid process

Mandibular condyleMandibular notch

Mandibular ramus

(a) External anatomy of the right side of the skull

Mandibular angle Coronoid process

Zygomaticprocess

Temporal bone

Page 12: The Axial Skeleton

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Figure 7.7b The floor of the cranial cavity.

Sphenoid

Anterior cranial fossa

Middle cranialfossa

Temporal bone(petrous part)

Posteriorcranial fossaParietal bone

Occipital bone

Foramenmagnum

(b) Superior view of the skull, calvaria removed

Ethmoidbone

Hypophyseal fossaof sella turcica

Lesserwing Greaterwing

Cribriformplate

Crista galli Frontal bone

Olfactoryforamina Optic canal

Foramenrotundum Foramen ovale

Foramenspinosum

Jugular foramen

Foramen lacerum

View

Page 13: The Axial Skeleton

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Figure 7.6b Inferior aspect of the skull, mandible removed.

Hard palate

Mandibularfossa

Mastoidprocess

ZygomaticarchForamen ovale

Foramen lacerumCarotid canal

Styloid process

Jugular foramenOccipital condyle

Foramen magnum

Superior nuchalline(b) Photo of inferior view of the skull

Foramen spinosum

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Skull Fractures

Page 15: The Axial Skeleton

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Figure 7.11a Detailed anatomy of the mandible and the maxilla.

Coronoidprocess

Mandibular foramen

Mentalforamen

Mandibularangle

Ramusofmandible

Mandibularcondyle

Mandibular notch

Mandibular fossaof temporal bone

Body of mandible

Alveolarmargin

(a) Mandible, right lateral view

Temporomandibularjoint

Page 16: The Axial Skeleton

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Broken Jaw

Page 17: The Axial Skeleton

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The Hyoid Bone

This is a “U” shaped bone. It is not connected to the skull.

It forms the base for the tongue.

Page 18: The Axial Skeleton

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The Spinal Column

The vertebral column consists of 26 irregular bones.

It provides the main axial support for the skeleton.

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Figure 7.16 The vertebral column.

Cervical curvature (concave)7 vertebrae, C1–C7

Thoracic curvature(convex)12 vertebrae,T1–T12

Lumbar curvature(concave)5 vertebrae, L1–L5

Sacral curvature(convex)5 fused vertebrae sacrum

Coccyx4 fused vertebrae

Anterior view Right lateral view

Spinousprocess

Transverseprocesses

Intervertebraldiscs

Intervertebralforamen

C1

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The Spinal Column

There are 7 cervical vertebrae

12 Thoracic vertebrae

5 Lumbar vertebrae

5 Sacral vertebrae

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Anterior and Posterior Aspects of the Skull

You have breakfast at

7

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Anterior and Posterior Aspects of the Skull

You have lunch at 12

Page 23: The Axial Skeleton

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Anterior and Posterior Aspects of the Skull

You have dinner at 5

Page 24: The Axial Skeleton

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Anterior and Posterior Aspects of the Skull

You have to go to the bathroom at 5 am

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The Spinal Column

The major supporting ligaments are the anterior and posterior longitudinal ligaments.

Page 26: The Axial Skeleton

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Figure 7.17a Ligaments and fibrocartilage discs uniting the vertebrae.

Supraspinous ligamentIntervertebraldisc

Anteriorlongitudinalligament

Intervertebral foramen

Posterior longitudinalligament

Anulus fibrosus

Nucleus pulposus

Sectioned bodyof vertebra

Transverse process

Sectionedspinous process

Ligamentum flavum

Interspinousligament

Inferior articular process

(a) Median section of three vertebrae, illustrating the composition of the discs and the ligaments

Page 27: The Axial Skeleton

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The Spinal Column

The anterior ligament attaches to the vertebrae and discs.

It prevents hyperextension (bending backward)

The posterior ligament is weak and resists hyperflexation.

Page 28: The Axial Skeleton

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The Spinal Column

The Intervertebral discs accounts for 25% of your height and acts as a shock absorber.

A herniated or slip discs is a common cause of back injuries.

Page 29: The Axial Skeleton

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Figure 7.17c Ligaments and fibrocartilage discs uniting the vertebrae.

Vertebral spinous process(posterior aspect of vertebra)

Spinal nerve root

Anulus fibrosusof disc

Herniated portionof disc

Nucleuspulposusof disc

Spinal cord

(c) Superior view of a herniated intervertebral disc

Transverseprocess

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Figure 7.17d Ligaments and fibrocartilage discs uniting the vertebrae.

Nucleuspulposus ofintact disc

(d) MRI of lumbar region of vertebral columnin sagittal section showing herniated disc

Herniatednucleuspulposus

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Scoliosis

Scoliosis is an abnormal curvature of the spine which can occur during adolescence, old age or during pregnancy.

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Scoliosis

• Lordosis. Also called swayback, the spine of a person with lordosis curves significantly inward at the lower back.

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• Kyphosis. Kyphosis is characterized by an abnormally rounded upper back (more than 50 degrees of curvature).

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• Scoliosis. A person with scoliosis has a sideways curve to their spine. The curve is often S-shaped or C-shaped

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The Cervical Vertebrae

These are the smallest with C1 and C2 modified for the skull.

In general cervical vertebrae have– An oval body– A short spinous process which is split except

for C7– A transverse foramen for the vertebral

arteries.

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Page 37: The Axial Skeleton

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The Thoracic Vertebrae

There are12 (T1-T12)

These have :

1) Circular vertebral foramen

2)A long spinous process that points downward.

3) Transverse processes have facets for the ribs

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Page 39: The Axial Skeleton

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Figure 7.20b Posterolateral views of articulated vertebrae.

Transverseprocess

Spinousprocess

Superior articularprocess

Transversecostal facet (fortubercle of rib)

Body

Intervertebraldisc

Inferior costalfacet (for headof rib)Inferior articularprocess

(b) Thoracic vertebrae

Page 40: The Axial Skeleton

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The Lumbar Vertebrae

There are 5(L1-L5)

These have :

1) Spinous process is short & flat

2) Vertebral foramen is triangular

3) articular processes face medially or laterally

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Superiorarticularprocess

Transverseprocess

Spinousprocess

Intervertebraldisc

Body

Inferiorarticularprocess

(c) Lumbar vertebrae

Figure 7.20c Posterolateral views of articulated vertebrae.

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The Sacral Vertebrae

There are 5 (S1-S5)

These are fused and articulates with L5 and the ileum

Page 43: The Axial Skeleton

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Figure 7.21 The sacrum and coccyx.

Coccyx

CoccyxAnteriorsacralforamina

Apex

Posteriorsacralforamina

Mediansacralcrest

Sacralpromontory

Sacralcanal

Sacralhiatus

BodyFacet of superiorarticular process

Lateralsacralcrest

Auricularsurface

Ala

Ala

(b) Posterior view

Bodyof firstsacralvertebra

Transverseridges (sites of vertebralfusion)

(a) Anterior view

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The Thoracic Cage

This is composed of the ribs, thoracic vertebrae dorsally and sternum ventrally.

Ribs 1-7 are true ribs because they attach directly to the sternum.

Page 45: The Axial Skeleton

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The Thoracic Cage

This is composed of the ribs, thoracic vertebrae dorsally and sternum ventrally.

Ribs 1-7 are true ribs because they attach directly to the sternum.

Ribs 8-10 are false ribs because they attach indirectly

Page 46: The Axial Skeleton

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The Thoracic Cage

This is composed of the ribs, thoracic vertebrae dorsally and sternum ventrally.

Ribs 1-7 are true ribs because they attach directly to the sternum.

Ribs 8-10 are false ribs because they attach indirectly

Ribs 11 & 12 are floating and are NOT attached to the sternum

Page 47: The Axial Skeleton

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Figure 7.22 The thoracic cage.

Intercostal spaces

Xiphisternaljoint

Heart

Sternalangle

Jugularnotch

Trueribs(1–7)

Falseribs(8–12)

Jugular notch

Clavicular notch

ManubriumSternal angleBodyXiphisternal jointXiphoid process

L1

VertebraFloatingribs (11, 12) (b) Midsagittal section through the

thorax, showing the relationship of surface anatomical landmarks of the thorax to the vertebral column

(a) Skeleton of the thoracic cage, anterior view

Sternum

Costalcartilage

Costalmargin

Page 48: The Axial Skeleton

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Figure 7.23c Ribs.

Junction withcostal cartilage

Shaft Head Neck

Articularfaceton tubercle

Costal angleCostal groove

Facets forarticulationwith vertebrae

(c) A typical rib (rib 6, right), posterior view