General Features of a Long Bone
- At each end of such a bone is an expanded portion called an epiphysis, which articulates (forms a joint) with another bone.
- One epiphysis, called the proximal epiphysis, is nearest to the center of the body.
- The other, called the distal epiphysis, is farthest from the center of the body.
- On its outer surface, the articulating portion of the epiphysis is coated with a layer of hyaline cartilage called articular cartilage.
- The shaft of the bone, between the epiphyses, is called the diaphysis.
- A tough, vascular covering of fibrous tissue called the periosteum.
- The wall of the diaphysis is mainly composed of tightly packed tissue called compact bone.
- The epiphyses, in contrast, are composed largely of spongy bone.
- Compact bone in the diaphysis of a long bone forms a semirigid tube, which has a hollow chamber called the medullary cavity.
- A thin layer of cells called the endosteum lines these areas, and a specialized type of soft connective tissue called marrow fills them.
Figure 4- Major parts of a long bone (This is a femur)