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