What anatomical term describes the fixed end of a muscle?

The term that describes the fixed end of a muscle is the origin. In anatomy, muscles are attached to bones at two points: the origin and the insertion. The origin is the attachment point that does not move during muscle contraction; it serves as the anchor point for the muscle. When the muscle contracts, it pulls on the insertion, which is the end of the muscle that typically moves. Thus, the origin is critical for understanding how muscles function in movement and stability.

The other terms in the choices refer to different aspects of muscle anatomy. The insertion is the movable attachment point of the muscle, while the belly refers to the fleshy, central part of the muscle that contracts. The head typically refers to a specific part or section of a muscle in certain contexts, rather than the anchor point. Understanding these terms helps clarify how muscles interact with bones to facilitate movement.