Humerus: anatomy, landmarks and muscle attachments

The humerus is the only bone of the upper arm. It links the shoulder to the elbow, and almost every muscle that moves the shoulder or the elbow attaches to it.

Upper end

• The rounded head fits into the shallow glenoid cavity of the scapula to form the shoulder joint.
• Just below it, the anatomical neck marks the edge of the joint capsule.
• The greater tubercle (lateral) and lesser tubercle (front) receive the rotator cuff tendons. Between them runs the intertubercular (bicipital) groove, which carries the tendon of the long head of the biceps. The pectoralis major, latissimus dorsi and teres major insert on its lips and floor.
• The surgical neck, just below the tubercles, is where fractures are most common. The axillary nerve wraps around it.

Shaft

• The deltoid tuberosity, on the lateral side, receives the deltoid.
• The radial groove spirals across the back of the shaft, carrying the radial nerve between the origins of the lateral and medial heads of the triceps.

Lower end

• The medial and lateral epicondyles anchor the forearm flexors (medial) and extensors (lateral). The ulnar nerve passes behind the medial epicondyle: the "funny bone".
• The trochlea (spool-shaped) articulates with the ulna; the capitulum (rounded) with the radius.
• The olecranon fossa at the back receives the olecranon when the elbow straightens.

Frequently asked questions

What is the difference between the anatomical and surgical neck?

The anatomical neck is just below the head, at the edge of the joint capsule. The surgical neck is lower, below the tubercles, and fractures there more often.

Which nerve runs in the radial groove?

The radial nerve, with the deep artery of the arm.

What does the humerus articulate with?

The scapula at the shoulder, and the ulna and radius at the elbow.

Sources

• OpenStax, Anatomy and Physiology 2e, 8.2 Bones of the upper limb
• Z-Anatomy, the libre 3D atlas of anatomy