Skeletal System Terminology Definitions

Long bones

Greater in length than width

Short bones

Similar in length and width

Flat bones

Flat and quite thin

Irregular bones

Do not fit into any other category

Sesamoid bones

Small bones formed within tendons

Articular cartilage

Hyaline cartilage covering the joint surface at the epiphyses

Compact bone

Bone tissue forming the walls of the diaphysis and the bony coverings of spongy bone

Diaphysis

Shaft of the long bone

Endosteum

Connective tissue membrane lining the medullary cavity

Epiphysis

Enlarged proximal and distal ends of a long bone

Epiphyseal line

Part of the bone that replaces the epiphyseal growth plate

Head

Rounded epiphysis

Medullary cavity

Space within the diaphysis

Neck

Bony connection between the head and diaphysis of the long bone; the anatomical neck occurs with the epiphyseal line, while the surgical neck occurs at the junction of the epiphysis and diaphysis where a joint replacement would be made

Periosteum

Dense connective tissue membrane covering the external bone surface

Red marrow

Red blood cell-forming tissue that fills the spaces of spongy bone tissue

Spongy bone

Bone tissue filling the epiphyses and lining the medullary cavity

Yellow marrow

Fatty material occupying the medullary cavity

Fissure

Narrow crevice

Foramen

Round or oval opening

Fossa

Shallow depression

Groove

Narrow depression

Meatus

Penetrating hole

Sinus

Air-filled cavity

Condyle

Rounded articular process

Crest

Prominent narrow ridge

Epicondyle

Elevated area on or above a condyle

Facet

Smooth, almost flat surface

Line (linea)

Small, narrow ridge

Ramus

Flat bridge of a bone

Spine

Sharp, narrow, usually pointed end

Trochanter

Large, blunt process

Tubercle

Small, rounded process

Tuberosity

Large, rounded or roughened process