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

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The Axial Skeleton

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The axial skeleton

The Axial Skeleton


The skull

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 skull1

The 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

The Skull


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

Sutures


Figure 7 2a the skull cranial and facial divisions and fossae

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

Bones of cranium (cranial vault)

Coronal

suture

Squamous

suture

Facial

bones

Lambdoid

suture

(a) Cranial and facial divisions of the skull


The floor

The floor is divided into the

anterior , middle and posterior fossae

The Floor


Figure 7 2b the skull cranial and facial divisons and fossae

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

Anterior cranial

fossa

Middle cranial

fossa

Posterior cranial

fossa

(b) Superior view of the cranial fossae


The axial skeleton

External Features


Anterior and posterior aspects of the skull

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


Anterior and posterior aspects

Anterior and Posterior Aspects

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


Figure 7 5a bones of the lateral aspect of the skull external and internal views

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

Frontal bone

Coronal suture

Sphenoid bone

(greater wing)

Parietal bone

Ethmoid bone

Temporal bone

Lacrimal bone

Lacrimal fossa

Lambdoid

suture

Squamous

suture

Nasal bone

Occipital

bone

Zygomatic

bone

Zygomatic

process

Maxilla

Occipitomastoid

suture

External acoustic

meatus

Alveolar

margins

Mastoid process

Styloid process

Mandibular condyle

Mandible

Mandibular notch

Mental foramen

Mandibular ramus

Coronoid process

Mandibular angle

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


Figure 7 7b the floor of the cranial cavity

Figure 7.7b The floor of the cranial cavity.

Crista galli

Frontal bone

Ethmoid

bone

Cribriform

plate

Olfactory

foramina

Anterior cranial

fossa

Optic canal

Foramen

rotundum

Lesser

wing

Sphenoid

Foramen ovale

Greater

wing

Foramen

spinosum

Middle cranial

fossa

Foramen lacerum

Hypophyseal fossa

of sella turcica

Jugular foramen

Temporal bone

(petrous part)

Foramen

magnum

Posterior

cranial fossa

View

Parietal bone

Occipital bone

(b) Superior view of the skull, calvaria removed


Figure 7 6b inferior aspect of the skull mandible removed

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

Hard palate

Zygomatic

arch

Foramen ovale

Foramen spinosum

Foramen lacerum

Mandibular

fossa

Carotid canal

Styloid process

Mastoid

process

Jugular foramen

Occipital condyle

Foramen magnum

Superior nuchal

line

(b) Photo of inferior view of the skull


Skull fractures

Skull Fractures


Figure 7 11a detailed anatomy of the mandible and the maxilla

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

Mandibular fossa

of temporal bone

Temporomandibular

joint

Mandibular notch

Coronoid

process

Mandibular

condyle

Mandibular foramen

Alveolar

margin

Ramus

of

mandible

Mental

foramen

Mandibular

angle

Body of mandible

(a) Mandible, right lateral view


Broken jaw

Broken Jaw


The hyoid bone

The Hyoid Bone

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

It forms the base for the tongue.


The spinal column

The Spinal Column

The vertebral column consists of 26 irregular bones.

It provides the main axial support for the skeleton.


Figure 7 16 the vertebral column

Figure 7.16 The vertebral column.

C1

Cervical curvature

(concave)

7 vertebrae, C1–C7

Spinous

process

Transverse

processes

Thoracic

curvature

(convex)

12 vertebrae,

T1–T12

Intervertebral

discs

Intervertebral

foramen

Lumbar curvature

(concave)

5 vertebrae, L1–L5

Sacral curvature

(convex)

5 fused vertebrae

sacrum

Coccyx

4 fused vertebrae

Anterior view

Right lateral view


The spinal column1

The Spinal Column

There are 7 cervical vertebrae

12 Thoracic vertebrae

5 Lumbar vertebrae

5 Sacral vertebrae


Anterior and posterior aspects of the skull1

Anterior and Posterior Aspects of the Skull

You have breakfast at

7


Anterior and posterior aspects of the skull2

Anterior and Posterior Aspects of the Skull

You have lunch at 12


Anterior and posterior aspects of the skull3

Anterior and Posterior Aspects of the Skull

You have dinner at 5


Anterior and posterior aspects of the skull4

Anterior and Posterior Aspects of the Skull

You have to go to the bathroom at 5 am


The spinal column2

The Spinal Column

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


Figure 7 17a ligaments and fibrocartilage discs uniting the vertebrae

Figure 7.17a Ligaments and fibrocartilage discs uniting the vertebrae.

Intervertebral

disc

Supraspinous ligament

Anterior

longitudinal

ligament

Transverse process

Sectioned

spinous process

Intervertebral foramen

Posterior longitudinal

ligament

Ligamentum flavum

Interspinous

ligament

Anulus fibrosus

Nucleus pulposus

Inferior articular process

Sectioned body

of vertebra

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


The spinal column3

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.


The spinal column4

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.


Figure 7 17c ligaments and fibrocartilage discs uniting the vertebrae

Figure 7.17c Ligaments and fibrocartilage discs uniting the vertebrae.

Vertebral spinous process

(posterior aspect of vertebra)

Spinal cord

Spinal nerve root

Transverse

process

Herniated portion

of disc

Anulus fibrosus

of disc

Nucleus

pulposus

of disc

(c) Superior view of a herniated intervertebral disc


Figure 7 17d ligaments and fibrocartilage discs uniting the vertebrae

Figure 7.17d Ligaments and fibrocartilage discs uniting the vertebrae.

Nucleus

pulposus of

intact disc

Herniatednucleus

pulposus

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


The cervical vertebrae

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.


The thoracic vertebrae

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


Figure 7 20b posterolateral views of articulated vertebrae

Figure 7.20b Posterolateral views of articulated vertebrae.

Superior articular

process

Transverse

process

Transverse

costal facet (for

tubercle of rib)

Intervertebral

disc

Body

Inferior costal

facet (for head

of rib)

Spinous

process

Inferior articular

process

(b) Thoracic vertebrae


The lumbar vertebrae

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


Figure 7 20c posterolateral views of articulated vertebrae

Figure 7.20c Posterolateral views of articulated vertebrae.

Superior

articular

process

Body

Transverse

process

Intervertebral

disc

Inferior

articular

process

Spinous

process

(c) Lumbar vertebrae


The sacral vertebrae

The Sacral Vertebrae

There are 5 (S1-S5)

These are fused and articulates with L5 and the ileum


Figure 7 21 the sacrum and coccyx

Figure 7.21 The sacrum and coccyx.

Facet of

superior

articular

process

Body

Sacral

canal

Ala

Sacral

promontory

Auricular

surface

Ala

Body

of first

sacral

vertebra

Median

sacral

crest

Lateral

sacral

crest

Posterior

sacral

foramina

Transverse

ridges (sites

of vertebral

fusion)

Sacral

hiatus

Anterior

sacral

foramina

Coccyx

Apex

(b) Posterior view

Coccyx

(a) Anterior view


The thoracic cage

The Thoracic Cage

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

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


The thoracic cage1

The Thoracic Cage

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

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

Ribs 8-10 are false ribs because they attach indirectly


The thoracic cage2

The Thoracic Cage

This is composed of the ribs, thoracic vertebrae dorsally andsternum 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


Figure 7 22 the thoracic cage

Figure 7.22 The thoracic cage.

Jugular notch

Clavicular notch

Manubrium

Sternal angle

Body

Sternum

Xiphisternal joint

Xiphoid process

True

ribs

(1–7)

Intercostal spaces

Jugular

notch

Sternal

angle

False

ribs

(8–12)

Heart

Costal

cartilage

Xiphisternal

joint

L1

Vertebra

Floating

ribs (11, 12)

Costal

margin

(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


Figure 7 23c ribs

Figure 7.23c Ribs.

Facets for

articulation

with vertebrae

Articular

facet

on tubercle

Shaft

Head

Neck

Costal angle

Junction with

costal cartilage

Costal groove

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


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