Browse the corpus

The humerus is the largest bone of the upper extremity and defines the human brachium (arm). It articulates proximally with the glenoid via the glenohumeral (GH) joint and distally with the radius and ulna at the elbow joint. The most proximal portion of the humerus is the head of the humerus, which forms a ball and socket joint with the glenoid cavity on the scapula.[1] Just inferior to the head of the humerus is the anatomical neck of the humerus, which divides the head of the humerus from the greater and lesser tubercles. The anatomical neck of the humerus is the residual epiphyseal plate. An intertubercular groove appears proximally, which demarcates the two tubercles vertically. Following the tubercles is the surgical neck of the humerus, a site commonly susceptible to fractures. Continuing distally is the cylindrical-shaped shaft of the humerus, which contains a deltoid tubercle on its lateral aspect and a radial groove on its posterior aspect (also referred to as the spiral groove).[2] At the distal portion of the humerus, there exists a widening of the bone that forms the medial and lateral epicondyles. The distal portion of the humerus ends with an area referred to as the condyle, which is composed of the trochlea, capitulum, olecranon, coronoid and radial fossae.[3]  On the anterior lateral surface of the condyle is the lateral capitulum, which articulates with the head of the radius bone, and on the anterior medial surface of the condyle is the trochlea, which articulates the trochlear notch of the ulna bone. The coronoid fossa is located superior to the trochlea and accommodates the coronoid process of the ulna and superior to the capitulum on the anterior surface of the condyle, which is the radial fossa which receives with the head of the radius, both upon flexion of the elbow joint. On the posterior surface of the condyle is the olecranon fossa, which articulates with the olecranon of the ulnar bone upon flexion of the elbow joint.[4]