Capitulum of the humerus

Capitulum of the humerus
Left humerus seen from front (capitulum visible at bottom right)
Left humerus seen from front (part of the Appendicular skeleton)
Details
Identifiers
Latin	Capitulum humeri
TA	A02.4.04.022
FMA	23373
Anatomical terms of bone []

In human anatomy of the arm, the lateral portion of the distal 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.

Lepidosaurs show a distinct capitellum and trochlea on the centre of the ventral (anterior in upright taxa) surface of the humerus at the distal end.

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.

In birds, where forelimb anatomy has adaptation for flight, its functional if notontogenetic equivalent is the dorsal condyle of the humerus.

Elbow joint. Deep dissection. Anterior view.

Elbow joint. Deep dissection. Posterior view.

Elbow joint. Deep dissection. Posterior view.

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918) Romer, A.S. 1976 Osteology of the reptiles. University of Chicago Press, Chicago.