Functions of the Skeletal System

Support

Structural support for the entire body

Storage

Stores calcium salts and lipids as energy reserves

Blood cell production

Produces red blood cells, white blood cells, and other blood elements

Protection

Surrounds and protects soft tissues and organs

Movement

Bones function as levers for skeletal muscles

Bone

Supporting connective tissue with specialized cells and a matrix of calcium salts and collagen fibers

Long bones

Bones that are longer than they are wide, e.g., humerus and femur

Short bones

Bones with roughly equal dimensions, e.g., carpal and tarsal bones

Flat bones

Thin and broad bones, e.g., parietal bones of the skull and ribs

Irregular bones

Bones with complex shapes, e.g., vertebrae and bones of the skull

Diaphysis

Central shaft of a long bone

Epiphysis

Expanded portions at each end of a long bone

Articular cartilage

Covers the epiphyses and allows for smooth joint movement

Compact bone

Relatively solid bone tissue

Spongy bone

Bone tissue resembling a network of bony rods or struts

Periosteum

Fibrous outer layer covering the outer surface of bone

Endosteum

Cellular layer covering the inner surfaces of bone

Osteon

Basic functional unit of compact bone, consisting of concentric layers of osteocytes around a central canal

Trabeculae

Rods or plates of spongy bone that form an open network

Perforating canals

Provide passageways for blood vessels between the central canals and the periosteum/marrow cavity

Lacunae

Small pockets in bone containing osteocytes

Canaliculi

Small channels that connect lacunae and allow for nutrient exchange between osteocytes and blood vessels

Osteocytes

Mature bone cells that maintain bone structure and assist in repairs

Osteoclasts

Giant cells that dissolve the bony matrix and regulate calcium and phosphate concentrations

Osteoblasts

Cells responsible for the production of new bone matrix and deposition of calcium salts

Ossification

Process of new bone formation by osteoblasts