In human anatomy of the arm, the lateral portion of the articular surface of the humerus consists of a smooth, rounded eminence, named the capitulum of the humerus. In non-human tetrapods, the name capitellum is generally used, with "capitulum" limited to the anteroventral articular facet of the rib (in archosauromorphs).
It articulates with the cupshaped depression on the head of the radius, and is limited to the front and lower part of the bone.
In non-avian archosaurs, including crocodiles, the capitellum and the trochlea are no longer bordered by distinct ect- and entepicondyles respectively, and the distal humerus consists two gently expanded condyles, one lateral and one medial, separated by a shallow groove and a supinator process. Romer (1976) homologizes the capitellum in archosauromorphs with the groove separating the medial and lateral condyles.