A dense fibrous membrane covering the surface of bones (except at their extremities) and serving as an attachment for tendons and muscles. It surrounds the shaft of long bones.

• A. Endosteum
• B. Periosteum
• C. Perichondrium
• D. Perimysium

Answer: (D)

The membrane described is the periosteum. It is a dense fibrous covering that lines the outer surface of bone, except where articular cartilage covers the ends of joints. It surrounds the shaft of long bones and provides a surface for tendon and muscle attachment through its collagen fibers that anchor into the bone. The periosteum has two layers: an outer fibrous layer and an inner osteogenic layer containing cells important for bone growth and repair. It is richly supplied with nerves and blood vessels, and Sharpey fibers help anchor it firmly to the bone.

This differs from the endosteum, which lines the inner surfaces of bone (like the medullary cavity); the perichondrium, which surrounds cartilage; and the perimysium, which surrounds muscle fascicles rather than bone.