What's the noun for ulna? Here's the word you're looking for.
ulna
(anatomy) The bone of the forearm that extends from the elbow to the wrist on the side opposite to the thumb, corresponding to the fibula of the hind limb. Also, the corresponding bone in the forelimb of any vertebrate.
“They had been crafted from the ulnae of the red-crowned crane and had between five and eight finger-holes.”
“The bones on which this species is founded are a pair of ulnae, one radius, four metatarsi, and one coracoid.”
“This process progresses to the development of caput ulnae syndrome in which the carpus subluxates volarly and supinates while the ulnar head displaces dorsally.”