Bone Anatomy and Markings

Foramen

Round or oval opening through a bone (passageway for blood vessels/nerves).

Process

Any bony prominence or projection that grows out from the surface (usually starts with a "T").

Head

Bony expansion carried on a narrow neck.

Neck

The narrow section connecting a head to the shaft.

Condyle

A rounded, smooth articular knob that helps form a joint.

Epicondyle

A raised area on or above a condyle.

Sinus

A cavity within a bone, filled with air and lined with mucous membrane.

Fissure

A narrow, slitlike opening.

Meatus

A canal-like passageway.

Trochanter

A very large, blunt, irregularly shaped projection (only on the femur).

Crest

A prominent, narrow ridge of bone.

Fossa

A shallow, basinlike depression in a bone.

Spine

A sharp, slender, pointed projection.

Ramus

An armlike bar or branch of bone.

Tubercle

A small, rounded projection.

Tuberosity

A large, rounded, and roughened projection.

Compact Bone

Structure: Dense, smooth, and homogeneous. Location: Forms the outer shell of bones and the diaphysis of long bones.

Spongy Bone

Structure: Made of small, needlelike pieces (trabeculae) with open, marrow-filled spaces. Location: Found in the epiphyses of long bones and the core of flat/short bones.

Diaphysis

Makes up most of bone's length; composed of compact bone.

Periosteum

Outside covering of the diaphysis; fibrous connective tissue membrane.

Epiphysis

Composed mostly of spongy bone enclosed by thin layer of compact bone.

Articular cartilage

Covers the external surface of the epiphyses; made of hyaline cartilage; decreases friction at joint surfaces.

Epiphyseal line

Remnant of the epiphyseal plate; seen in adult bones.

Epiphyseal plate

Flat plate of hyaline cartilage seen in young, growing bone; causes lengthwise growth of a long bone.

Endosteum

Lines the inner surface of the shaft; made of connective tissue.

Medullary cavity

Cavity inside the shaft; contains yellow marrow in adults and red marrow for blood cell formation until age 6 or 7.