In human anatomy of the arm, the capitulum of the humerus is a smooth, rounded eminence on the lateral portion of the distal articular surface of the
humerus. It articulates with the cup-shaped depression on the
head of the radius, and is limited to the front and lower part of the bone.
In non-human tetrapods, the name capitellum is generally used, with "capitulum" limited to the anteroventral articular facet of the rib (in archosauromorphs).
Lepidosauromorpha
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.
Archosauromorpha
In non-avian
archosaurs, including crocodiles, the capitellum and the trochlea are no longer bordered by distinct etc.- 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
bird
Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
s, where forelimb anatomy has an
adaptation for flight, its functional if not
equivalent is the dorsal condyle of the humerus.
Additional images
File:Elbow joint - deep dissection (anterior view, human cadaver).jpg, Elbow joint. Deep dissection. Anterior view.
File:Slide1bgbg.JPG, Elbow joint. Deep dissection. Posterior view.
File:Slide3bgbg.JPG, Elbow joint. Deep dissection. Posterior view.
References
* Romer, A.S. 1976 Osteology of the reptiles. University of Chicago Press, Chicago.
External links
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