The humerus is the long bone in the upper arm. It is located between the elbow joint and the shoulder. At the elbow, it connects primarily to the ulna, as the forearm’s radial bone connects to the wrist. At the shoulder, the humerus connects to the frame of the body via the glenoid fossa of the scapula. The humerus is the foundation to which many muscles insert, such as the deltoid, the pectoralis major, and others. The brachial artery travels most of the bone’s length, before it subdivides into the ulnar and radial arteries at the elbow. In the upper arm, the brachial artery branches into several arteries, distributing oxygenated blood from the lungs and heart. The radial nerve runs a similar course over the bone and into the forearm. Because it connects at the shoulder with a rotational joint, the humerus is instrumental in supporting many of the arm’s functions. For example, the humerus supports all lifting and physical activities. The humerus is one of the longest bones in the body. This means it is also one of the most commonly broken or fractured.