Bones of the Upper Limb: Humerus

The upper limb includes the arm, forearm, wrist, and hand bones.

The humerus is the only long bone of the arm; it consists of the head, shaft, and condyles.

At the proximal end, the head articulates with the shoulder blade's glenoid cavity and allows the arms to hang freely at the sides.

Lateral to the head, prominent projections, the greater and lesser tubercles anchor the rotator cuff muscles, stably attaching the humerus to the scapula.

Between the tubercles, a central bicipital groove allows the bicep tendon to pass through, which helps flex the arm.

About midway through the shaft, a rough elevation, the deltoid tuberosity, attaches the shoulder's deltoid muscle.

Posteriorly, the radial groove provides passage to the radial nerve to control motor and sensory responses of the muscles during elbow extension.

Condyles–trochlea and capitulum attach the humerus to the forearm bones— ulna and radius, forming the elbow joint.

The ulnar nerve crossing the elbow joint often produces a tingling sensation upon being hit as it gets rubbed against the humerus.