The humerus is the long bone in the upper arm that extends from the shoulder to the elbow. It plays a crucial role in the movement of the arm and supports various activities such as lifting and throwing. The humerus has three main parts: the head, which fits into the shoulder socket; the shaft, which is the long middle section; and the distal end, which connects to the bones of the forearm. In addition to its structural importance, the humerus serves as an attachment point for several muscles, including those involved in flexion and extension of the arm. Injuries to the humerus, such as fractures, can significantly impact arm function and require medical attention for proper healing.