The Collaborative International Dictionary of English v.0.48:

Trochlea \Troch"le*a\, n. [L., a case or sheaf containing one or
   more pulleys, Gr. ?. See Trochilics.]
   1. (Mach.) A pulley. [Obs.]
      [1913 Webster]

   2. (Anat.) A pulley, or a structure resembling a pulley; as,
      the trochlea, or pulleylike end, of the humerus, which
      articulates with the ulna; or the trochlea, or fibrous
      ring, in the upper part of the orbit, through which the
      superior oblique, or trochlear, muscle of the eye passes.
      [1913 Webster]