Anat. [L. trochlea: cf. Gr. τροχιλία, -χιλέα, -χαλία sheaf of a pulley.] A pulley-like structure or arrangement of parts, with a smooth surface upon which some other part, as a bone or tendon, slides;
spec. (a) the surface of the inner condyle of the humerus at the elbow-joint, with which the ulna articulates; (b) the cartilaginous loop through which the superior oblique muscle of the eye passes; (c) the orifice of the metathorax in hymenopterous insects, through which the tendon of the abdomen passes.
1693. trans. Blancard’s Phys. Dict. (ed. 2), Trochlea, the same that Bathmis.
1826. Kirby & Spence, Entomol., xxxvi. III. 701. Here the upper orifice in the trunk is the pulley (trochlea), the tendon is the rope (funiculus), and the abdomen is the weight to be lifted.
1854. Owen, Skel. & Teeth (1855), 64. The distal end of the tibia forms a transverse pulley or trochlea.
1857. Dunglison, Med. Lex., Trochlea, a pulley;… for example, the articular surface at the lower extremity of the os humeri; so called from its forming a kind of pulley on which the ulna moves…. Also, the cartilaginous pulley over which the tendon of the trochlearis muscle passes, at the upper and inner part of the orbit.
