The capitellum, also refered to as the capitulum, is the lateral part of the humeral condyle that articulates with the radial head.
The capitellum is only the anterior and inferior part of the lateral humeral condyle. Between it and the radius usually lies a synovial fold. The capitellum should be located such that a radiocapitellar line can be drawn through it from the radius. Blood is supplied by perforating vessels from the recurrent radial artery, however, there can be perforating vessels from the interosseus recurrent and/or radial collateral arteries as well .
Psuedodefect of the capitellum is an anatomic variant.
The capitellum is the first ossification center in the elbow to ossify if development of the joint is normal. This center should have become apparent by two years of age.
History and etymology
Capitellum is derived from the Latin word for head, caput, and the suffix ellum, which is diminuitive; thus the word could be interpreted to imply a little head.