from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Located behind an axis of the body, as the lateral aspect of the lower leg or the medial aspect of the upper arm.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Situated behind any transverse axis in the body of an animal; caudal; posterior.
from the GNU version of the Collaborative International Dictionary of English
- adj. Situated behind any transverse axis in the body of an animal; caudal; posterior; especially, behind, or on the caudal or posterior (that is, ulnar or fibular) side of, the axis of a vertebrate limb.
from The Century Dictionary and Cyclopedia
- Of or pertaining to, or situated upon, that side of the axis of either fore or hind limb of a vertebrate which is posterior when the limb is extended at a right angle to the long axis of the body: opposed to preaxial.
Of the surfaces, onethe future flexor surface of the limbis directed ventrally; the other, the extensor surface, dorsally; one border, the preaxial, looks forward toward the cephalic end of the embryo, and the other, the postaxial, backward toward the caudal end.
The preaxial part is derived from the anterior segments, the postaxial from the posterior segments of the limb-bud; and this explains, to a large extent, the innervation of the adult limb, the nerves of the more anterior segments being distributed along the preaxial (radial or tibial), and those of the more posterior along the postaxial (ulnar or fibular) border of the limb.
The radius and tibia are, at an early stage in development, on the anterior edge of their respective limbs; the ulna and fibula, posterior; the former are spoken of as preaxial in position, the latter as postaxial.