Humerus or Arm
The arm has one bone called the humerus, which consists of a body and two articular ends. The proximal part of the humerus articulates with the shoulder girdle. The distal humerus is broad and flattened and presents numerous processes and depressions.
Humeral Condyle, Trochlea and Capitulum
The distal end of the humerus is called the humeral condyle and includes two smooth elevations for articulation with the bones of the forearm. The trochlea on the medial side and the capitulum on the lateral side. The medial and lateral epicondyle are superior to the condyle and easily palpated.
Coronoid Fossa
On the anterior surface superior to the trochlea, a shallow depression called the coronoid fossa receives the coronoid process when the elbow is flexed. The relatively small radial fossa, which receives the radial head when the elbow is flexed, is located lateral to the coronoid fossa and proximal to the capitulum.
Olecranon Fossa
The olecranon fossa is a deep depression found immediately behind the coronoid fossa on the posterior surface and accommodates the olecranon process when the elbow is extended.
Head, Neck and Body
The proximal end of the humerus contains the head, which is large, smooth and rounded and lies in an oblique plane on the superomedial side. Just below the head, lying in the same oblique plane, is the narrow, constricted anatomic neck. The constriction of the body just below the tubercles is called the surgical neck, which is the site of many fracture.
Lesser Tubercle
The lesser tubercle is situated on the anterior surface of the bone immediately below the anatomic neck. The tendon of the subscapularis muscle inserts at the lesser tubercle.
Greater Tubercle
The greater tubercle is located on the lateral surface of the bone just below the anatomic neck and is separated from the lesser tubercle by a deep depression called the intertubercular groove.
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