BUNDLE 3: THE SKELETON & BODY CAVITIES
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THE SKELETON
Bony framework of the body.
• Forms cavities and fossae that protect structures
• Forms joints
• Gives attachment to muscles
TWO PARTS OF THE SKELETON
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1. AXIAL SKELETON
Consists of: skull, vertebral column, sternum, and ribs.
SKULL
Described in two parts: Cranium (contains brain) and Face.
• Consists of several bones which develop separately but fuse together as they mature
• **Mandible (lower jaw)**: Only movable bone
Functions:
• Protect delicate structures (brain, eye, inner ear)
• Maintain patency of nasal passage enabling breathing
• Eating (movement of mandible allows chewing)
VERTEBRAL COLUMN
Consists of 24 moveable bones plus sacrum and coccyx.
• Bones separated by fibrocartilage **intervertebral discs**
Five parts (numbered):
1. **Cervical**: 7 vertebrae
• First vertebra = **Atlas**; forms joint with skull
2. **Thoracic**: 12 vertebrae
3. **Lumbar**: 5 vertebrae
4. **Sacrum**: 1 (5 fused); articulates with 5th lumbar above, coccyx below, and
innominate (pelvic/hip) bone at each side
5. **Coccyx**: 1 (4 fused); articulates with sacrum above
Functions:
__________________________________________________
THE SKELETON
Bony framework of the body.
• Forms cavities and fossae that protect structures
• Forms joints
• Gives attachment to muscles
TWO PARTS OF THE SKELETON
__________________________________________________
1. AXIAL SKELETON
Consists of: skull, vertebral column, sternum, and ribs.
SKULL
Described in two parts: Cranium (contains brain) and Face.
• Consists of several bones which develop separately but fuse together as they mature
• **Mandible (lower jaw)**: Only movable bone
Functions:
• Protect delicate structures (brain, eye, inner ear)
• Maintain patency of nasal passage enabling breathing
• Eating (movement of mandible allows chewing)
VERTEBRAL COLUMN
Consists of 24 moveable bones plus sacrum and coccyx.
• Bones separated by fibrocartilage **intervertebral discs**
Five parts (numbered):
1. **Cervical**: 7 vertebrae
• First vertebra = **Atlas**; forms joint with skull
2. **Thoracic**: 12 vertebrae
3. **Lumbar**: 5 vertebrae
4. **Sacrum**: 1 (5 fused); articulates with 5th lumbar above, coccyx below, and
innominate (pelvic/hip) bone at each side
5. **Coccyx**: 1 (4 fused); articulates with sacrum above
Functions:
