1. The upper bone of the arm from the elbow (articulating with the ulna and the radius) to the shoulder joint, where it articulates with the scapula.
2. The long bone of the human upper arm or of a forelimb in other animals.
3. The bones of the upper arms, extending from the elbows to the shoulders; the humeri.
4. The long bone of the upper forelimb in tetrapods; the upper arm bone in humans, extending from the shoulder to the elbow.

Its rounded upper head articulates with the glenoid cavity of the scapula in a ball-and-socket joint.

The lower end is modified to form an articular surface (condyle) for the radius and the ulna, which produce the hinge joint of the elbow.

Physical injury that is sufficient to break the bone of the upper arm or forelimb that are forming joints at the shoulder and the elbow: If the fracture of the humerus is at the upper end, the arm is on a wire splint for about four weeks.

Usually movements of the fracture of the humerus at the elbow and wrist are started early, and active conditions of the shoulder will begin in about three weeks.