What is the interosseous membrane?

• A. A sheath around a nerve
• B. The membrane lining the joint cavity
• C. The membrane between bones
• D. A membrane covering the bone surface

Answer: (C)

The interosseous membrane is a thick sheet of dense connective tissue that fills the space between two adjacent long bones in the same limb, most notably between the radius and ulna. It binds the bones together, helps stabilize the forearm, and distributes some of the load from one bone to the other during activities like weight-bearing or gripping. It also provides a surface for muscle attachments and helps maintain the proper distance between the bones during movement, aiding pronation and supination. It is not a sheath around a nerve, not the lining of a joint cavity, and not the membrane that covers the bone surface.