What is the name of the sheath made of connective tissue that covers the connecting bones at a joint?

The correct answer is the joint capsule. The joint capsule is a crucial structure in joints that consists of connective tissue and serves to encase the joint, providing stability and protection to the connecting bones. It is typically composed of two layers: an outer fibrous layer that strengthens the joint and an inner synovial membrane that produces synovial fluid, which lubricates the joint and reduces friction during movement. This architecture allows the joint capsule to play a critical role in facilitating smooth movement and providing structural integrity to the joint.

In contrast, visceral muscle refers to muscle tissue found in the walls of internal organs and is not related to joint structures. Antagonists are muscles that oppose the action of other muscles during movement, playing a role in muscular coordination but not in joint structure. Insertion is a term used to describe the attachment site of a muscle on a bone, indicating where the muscle exerts its force, rather than relating to the connective tissue surrounding joints. Therefore, the joint capsule is specifically designed for the protection and function of joints.