Where it is
Upper arm. Its head articulates with the scapula at the shoulder; its lower end articulates with the radius and ulna at the elbow.
What it does
Supports the arm and anchors the muscles that move the shoulder and elbow, including the deltoid, biceps and triceps.
Clinical relevance
- The radial nerve runs in a groove along the shaft: a mid-shaft fracture can cause wrist drop.
- Supracondylar fractures (just above the elbow) in children can injure the brachial artery.
Nursing focus
- After a humerus fracture, check radial pulse, capillary refill and the ability to extend the wrist and fingers.