trochlea of humerus
The medial portion of the articular surface of the humerus is named the trochlea, and presents a deep depression between two well-marked borders; it is convex from before backward, concave from side to side, and occupies the anterior, lower, and posterior parts of the extremity. It is directly inferior to the most prominent anterior humeral fossia, the Coronoid fossia. It articulates with the ulna.