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The Axial Skeleton

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Page 1: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

The Axial Skeleton

Page 2: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

THE SKELETAL SYSTEMThe Axial Skeleton

• The skeleton consists of– Bones (206)– Cartilages– Joints – also called articulations, are the junctions

between skeletal elements– Ligaments – connect bones

• Divided into axial and appendicular

Page 3: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

• Axial skeleton - forms long axis of body– Skull– Vertebral column– Thoracic cage

• Appendicular skeleton – appendages and what they attach to– Upper limbs (arms)– Pectoral girdle (shoulder)– Lower limbs (legs)– Pelvic girdle

Page 4: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Axial skeletonSkullVertebral columnThoracic cage

Axial skeleton is shown in green

Page 5: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are
Page 6: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

The Skull• Cranial bones (or cranium)– Enclose the cranial cavity, which supports and protects the

brain– Attachment sites for some head and neck muscles

• Facial bones (anterior aspect of skull)– Form framework of face– Form cavities for sense organs of sight, taste and smell– Provides openings for passage of air and food– Hold the teeth– Anchor the muscles of the face

Page 7: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Cranium• Vault – “calvaria” = skullcap– Forms superior, lateral and

posterior aspects of skull, and forehead

• Base or floor: inferior part– Prominent bony ridges divide

cranial base into 3 “fossae” (steps) – anterior, middle and posterior

Anterior cranial fossa

Middle cranial fossa

Posterior cranial fossa

(looking down on the floor of the skull)

Page 8: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Cranial bones

• Frontal bone• Parietal bones (paired)• Occipital bone• Temporal bones (paired)• Sphenoid bone• Ethmoid bone

Page 9: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Cranial bones

parietal parietalfrontal

temporal

parietal

occipital

_______sphenoid_____ethmoid

occipital

Page 10: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Temporal bones

this is the right temporal bone looking at it from the right side

Page 11: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Sphenoid

Ethmoid Small cranial bones…

Page 12: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Sutures

• Immovable, interlocking joints of flat bones of skull• Irregular, saw-toothed appearance

• Largest 4 skull sutures: where bones articulate with parietal bones– Coronal– Sagittal– Squamous– Lambdoid

Page 13: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Find: coronal, squamous and lamboid sutures

Page 14: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Find: sagittal and lambdoid sutures

Page 15: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

• Cranial “cavity” – houses brain

• Smaller cavities– Housing middle and inner ear– Nasal cavity– Orbits– Sinuses

• Openings (foramina, canals, fissures) for:– Spinal cord– Blood vessels– Twelve cranial nerves: I-XII

Page 16: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Remember, the skull is composed of:1. Cranial bones (or cranium)

and

2. Facial bones (anterior aspect of skull)– Form framework of face– Form cavities for sense organs of sight, taste and

smell– Provides openings for passage of air and food– Hold the teeth– Anchor the muscles of the face

Page 17: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Facial bones• Mandible• Vomer• Maxillae (paired)• Zygomatics (paired)• Nasal (paired)• Lacrimal (paired)• Palatines (paired)• Inferior nasal conchae (paired)

Page 18: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

MandibleVomerMaxillae (paired)Zygomatics (paired)Nasal (paired)Lacrimal (paired)Palatines (paired)Inferior nasal conchae (paired)

Facial bones:

Page 19: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are
Page 20: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are
Page 21: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are
Page 22: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are
Page 23: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are
Page 24: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are
Page 25: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Mandible (lower jaw)

Maxilla (there are 2 which fuse, forming the upper jaw)

Page 26: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Nasal cavity

• Of bone and cartilagenasal bone

maxilla___________

Page 27: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

OrbitCone-shaped bony cavities holding the eyes, muscles that move the eyes, some fat and tear-producing glands

optic nerve passes out through it

Page 28: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Paranasal sinuses• Air-filled sacs in the bones• “Paranasal” because they cluster around and

connect to the nasal cavity

Page 29: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Hyoid bone

• Only bone which does not articulate with any other bone

• Moveable base for the tongue

• Points of attachment for neck muscles that raise and lower the larynx during swallowing

Page 30: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

SkullVertebral columnThoracic cage

Axial skeleton is shown in green

Page 31: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

The Vertebral Column

• Fetus and infant: 33 separate bones or vertebrae

• Adult: 24 vertebrae– Inferior 9 have fused forming• The sacrum (5) and• The coccyx (4)

Page 32: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Vertebrae

• Cervical – 7• Thoracic - 12• Lumbar - 5• Sacrum (5 fused)• Coccyx (4 fused)

Page 33: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Spinal curvatures

• Cervical and lumbar are concave posteriorly* (lordosis)

• Thoracic and sacral are convex posteriorly* (kyphosis)

• Abnormal: – Too much of either– Scoliosis (more than 10 degrees of

lateral curvature)

*when viewed from the side

Page 34: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are
Page 35: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Abnormal curvatures

Page 36: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Disorders of the axial skeleton

• Scoliosis (over 10% curvature)

• Kyphosis

• Lordosis

• Vertebral compression fractures

• Spinal stenosis

Page 37: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Non-bony parts• Intervertebral

discs – anulus fibrosis

and nucleus pulposus)

• Anterior longitudinal ligament

• Posterior longitudinal ligament

• Ligamentum flavum

Page 38: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Anterior longitudinal ligament: wide, strong and attaches to vertebrae as well as discs (prevents hyperextension)

Posterior longitudinal ligament: narrow and relatively weak, attaching only to discs

*

Page 39: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Structure of a typical vertebra

Page 40: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Cervical vertebrae (C1-C7)C1 (atlas)

C2 (axis)

Page 41: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

• Smallest• Lightest• Most flexible• Triangular vertebral

foramen• Transverse processes

have foramina (transverse foramen)

• Spinous process bifid (forked) except for C7

Cervical Vertebrae

Page 42: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

• Heart shaped body• Additional small

costal facets (costal=ribs)

• Round or oval vertebral foramen

• Form posterior part of rib cage

Thoracic Vertebrae T1-T12

Page 43: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

• Massive blocklike bodies

• Short, thick hatchet-shaped spinous processes

• Limited mobility

Lumbar Vertebrae L1-L5

Page 44: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

The SacrumShapes posterior wall of pelvis

Composite bone of 5 fused vertebrae

Sacral foramina allow passage of vessels & nerves

Coccyx(the tailbone)

Page 45: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Remember that the Axial skeleton includes:

SkullVertebral columnThoracic cage

Axial skeleton is shown in green

Page 46: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

The Thoracic Cage

Page 47: The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of – Bones (206) – Cartilages – Joints – also called articulations, are

Sternum Ribs

• Manubrium

• Body

• Xiphoid process

• True ribs 1-7

• False ribs 8-12

• Floating ribs 11,12