Long Bone Anatomy - bone parts

Epiphysis

The expanded portion at each end of the bone.

Epiphyseal growth plate

The cartilaginous region where growth in the length of the bone occurs

Diaphysis

The shaft of the bone

Metaphysis

The wide portion between the epiphysis and the narrow diaphysis. It contains the growth plate – the part of the bone that grows during childhood

Articular hyaline cartilage

Covers the bone ends

Periosteum

A tough, fibrous fascial sheath covering the whole bone

Compact / cortical bone

Solid, strong and resistant to bending

Cancellous / trabecular bone

Gives the bone elastic strength to resist compression forces

Medullary cavity

The hollow cavity down the center of the compact bone

Endosteum

The membrane that lines the cavity

Red or yellow marrow

Produces blood cells or stores fat, respectively

Blood vessels

In a typical long bone, blood is supplied by three routes:

1. an artery to the diaphysis and metaphysis

2. an artery to the periosteum and outer cortical bone

3. an artery to the epiphysis and cartilage.

Ossification

In the human embryo, the skeleton is composed of either fibrous membranes or hyaline cartilage. Parts of the skeletal system begin to form during the first few weeks of pre-natal development and bony structures