What part of the muscle is attached to another muscle or joint?

The insertion of a muscle is the point where it attaches to another muscle or to a joint. This attachment is crucial for muscle function, as the insertion is typically located on the more movable bone or structure in relation to the muscle's origin. When a muscle contracts, it pulls on its insertion point, leading to movement at the joint involved. The position of the insertion allows for a more extensive range of motion, enabling activities such as lifting, bending, or rotating.

In contrast, the origin is typically the fixed attachment point of the muscle, while the belly refers to the central part of the muscle itself. Tendons, on the other hand, are connective tissues that link muscles to bones, rather than being specific attachment points on muscles. Understanding the role of the insertion helps clarify how muscles contribute to movement in the body.