The Skeletal System
NO BONES ABOUT IT!
Did you know?
The adult skeleton has 206 bones
Things to Know:Oste “bone”
Art “joint”
-blast “germ” or embryonic
-clast “broken”
-cyte “cell”
Peri- “around”
Dia- “between or across”
Epi- “upon”
Hemat- “blood”
The Skeletal System
• Parts of the skeletal system– Bones (skeleton)– Joints (flexibility)– Cartilages (cushion)– Ligaments (connect bone to bone)
Functions of Bones
• Support the body (internal framework)
• Protect soft organs (vertebrae)
• L
• Allow movement due to attached skeletal muscles
• Store minerals and fats (fats, clacium, phosphorus)
• Hematopoiesis (Blood cell formation)
The Skeletal System• Two subdivisions of the skeleton
1. Axial skeleton
(skull, ribs, spine)
2. Appendicular skeleton
(pectoral girdle, pelvic girdle,
bones of limbs)
Figure 5.1a
Shaft
Head
Head 1. Long bones
Have a shaft with heads at both ends
Typically longer than they are wide
Contain mostly compact bone
Examples:
Femur (longest bone in the body)
Classification of Bones by Shape
Anatomy of a Long Bone• Diaphysis
– Compact bone– Protected by periosteum (membrane)
• Epiphysis – Ends of the bone– Thin layer of compact bone– But mainly spongy bone in the middle– Protected by articular cartilage
Anatomy of a Long Bone
• Medullary cavity – Cavity inside of the diaphysis– Contains yellow marrow
(mostly adipose) in adults– Contains red marrow
(for blood cell formation)
in infants
Figure 5.1b
2. Short bones
Generally cube-shape
Contain mostly spongy bone
Example:
Carpals
Tarsals
Patella
3. Flat bones– Thin, flattened, and usually curved– Two thin layers of compact bone inside– Layer of spongy bone inside
Example: • Skull• Ribs• Sternum
4. Irregular bones– Irregular shape– Do not fit into other bone classification
categories– Example:
• Vertebrae • Hip bones