1. Posterior to the axis of the body or any limb, the latter being in the anatomic position. 2. Denoting the portion of a limb bud that lies caudal to the axis of the limb : the ulnar aspect of the upper limb and the fibular aspect of the lower limb.
* * *
post·ax·i·al -'ak-sē-əl adj of or relating to the ulnar side of the vertebrate forelimb or the fibular side of the hind limb also of or relating to the side of an animal or side of one of its limbs that is posterior to the axis of its body or limbs
* * *
post·ax·i·al (pōst-akґse-əl) posterior to an axis. In anatomical usage, this refers to the medial (ulnar) aspect of the upper limb, and the lateral (fibular) aspect of the lower limb.Medical dictionary. 2011.