Panner disease is an osteochondrosis of the capitellum of the elbow.

Romer (1976) homologizes the capitellum in archosauromorphs with the groove separating the medial and lateral condyles.

In non-human tetrapods, the name capitellum is generally used, with "capitulum" limited to the anteroventral articular facet of the rib (in archosauromorphs).

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.

The radial head has a cylindrical form, and on its upper surface is a shallow cup or fovea for articulation with the capitulum (or capitellum) of the humerus.

The pathologic lesion is generally a tear in the attachment of the annular ligament to the periosteum of the radial neck, with the detached portion becoming trapped between the head of the radius and the capitellum.

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.