troch·le·a 
(trŏklē-ə)
(trŏklē-ə)n. pl. troch·le·ae (-lē-ē′)
An anatomical structure that resembles a pulley, especially the part of the distal end of the humerus that articulates with the ulna.
[Latin, system of pulleys, from Greek trokhileia; akin to trekhein, to run.]