ul·na 
(ŭlnə)
(ŭlnə)n. pl. ul·nas or ul·nae (-nē)
1. The bone extending from the elbow to the wrist on the side opposite to the thumb in humans.
2. A corresponding bone in the forelimb of other vertebrates.
[Latin, elbow, forearm; see el- in the Appendix of Indo-European roots.]
ulnar adj.