Distal extremity of radius

The distal extremity of the radius is often wrongly called the trochlea of the radius (Trochlea radii) and holds in principle an articular surface for the ulna, another for the carpus and a more or less tuberous circumference.

In Carnivorous and Primates, the articular surface for the ulna is particularly distinct; it is concave transversally, covered with cartilage, and constitutes the ulnar notch of the radius (Incisura ulnaris radii).

In Rabbits, it becomes planiform and rough.

In Ungulates, it participates to the synostosis taht merges the two bones of the forearm together and isn't visible anymore.

In Carnivorous and Primates The articular surface for the carpus (Facies articularis carpea) is formed,, by a transversally stretched articular cavity, incompletely subdivided into two parts by a weak dorsopalmar crest, whose weaker is completed by the adjacent ulnar surface. It is overlooked on the palmar side by a very strong transverse crest (Crista transversa) that corresponds to a strong ligamentar attachment.

In Ungulates, the specialisation of the movements goes with the development of strong articular condyles on the palmar side. They push the double glenoidal cavity dorsally, that becomes relatively narrow. Their distal antebrachial surface is very irregular and formed on the palmar side by the juxtaposition of two dorsal cavities and two unequal condyles (more a third one formed by the ulna). Between these and the transversal palmar crest are located strong irregular depressions.