Chaha

ḫumma, ḫuma - heel, elbow (EDG 343)

PS
*kVm- - articulation, joint, wrist (SED I No. 143; Kogan 2011: 215)
*-­u-­ may be a secondary development due to the influence of *m-­. As a nominal anatomic term based on Akk. and M. Eth. only.