Classification of Bones and Bone Structures

Long Bone

Longer than they are wide. Mechanical function is movement.

Short Bone

Generally cube shaped. Unites other bones and functions in movement.

Flat Bone

Thin, flattened, and usually curved. Mechanical function is protection.

Irregular Bone

All other bones.

Compact bone

Hard, dense bone that makes up the outer layer of bones.

Spongy bone

Lightweight, porous bone found inside bones

Diaphysis

The shaft or long middle part of a bone

Epiphysis

The ends of a long bone

Peristeum

Tough outer covering of a bone

Endosteum

Thin lining on the inside of a bone

Sharpey’s fibers

Fibers that attach the periosteum to the bone

Medullary Cavity (Yellow Marrow)

Hollow space inside the shaft that contains yellow bone marrow.

Red Marrow

Bone marrow that makes blood cells.

Bone Matrix

Hard material that makes up bone tissue.

Lamellae

Thin layers of bone tissue

Lacunae

Small spaces that hold osteocytes

Osteoblasts

Cells that build new bone.

Osteocytes

Mature bone cells that maintain bone tissue.

Osteoclasts

Cells that break down old bone.

Osteon

The main structural unit of compact bone

Central (haversian) Canals

Channels in an osteon that contain blood vessels and nerves.

Canaliculi

Tiny channels that connect bone cells to each other.

Perforating (Volkmann’s) Canals

Channels that connect central canals to the outer surface of bones.

Trabecula

A thin supporting structure/beam in spongy bone.