The distal (third) phalanx differs between species to conform to the hoof or to the claw that encloses it. They have in common a an articular facet, a parietal surface and solar surface.
The parietal surface of the distal phalanx is situated dorsally.
In dogs, the parietal surface is subdivided laterally in a palmar surface and a solar surface.
In horses, the parietal surface is separated from the solar surface by the solar border, and from the articular surface by the coronary border. The parietal surface is convex from side to side and is perforated or notched by numerous foramina and grooves for blood vessels and nerves. The medial and lateral parietal grooves run on the parietal surface of the distal phalanx, they encompass blood vessels (dorsal branches or palmar digital artery) and terminate dorsally with the largest parietal foramina and terminate palmarly in the notch of the palmar process.