Trochlea

Trochlea (Latin for pulley) is a term in anatomy. It refers to a grooved structure reminiscent of a pulley's wheel.

Related to joints
Most commonly, trochleae bear the articular surface of saddle and other joints:
 * Trochlea of humerus (part of the elbow hinge joint with the ulna)
 * Trochlea of femur (forming the knee hinge joint with the patella)
 * The trochlea tali in the superior surface of the body of talus (part of the ankle hinge joint with the tibia)
 * Trochlear process of the calcaneus
 * In quadrupeds, the trochlea of Radius (bone)
 * The "knuckles" of the tarsometatarsus which articulate with the proximal phalanges in a bird's foot

Related to muscles
It also can refer to structures which serve as a guide for muscles:
 * Trochlea of superior oblique (see also superior oblique muscle), a mover of the eye which is supplied by the trochlear nerve, or fourth cranial nerve