The base of proximal phalanx is the proximal part of the phalanx. It bears and articular surface (fovea articularis).
In horses, the base of proximal phalange is wider than the head. The articular surface of the base is subdivided into a larger medial cavity and a smaller lateral one by a sagittal groove. On posterior part of the base are the medial and lateral palmar eminences that are prominent structures where respectively the medial part and the lateral part of the collateral ligaments of the fetlock joint and the medial and lateral short sesamoid ligaments insert.