extrinsic muscle (em) [L, extrinsecus, on the outside] , 1. a muscle that is outside the organ it controls, as the extraocular muscles that control eye movements. Extrinsic muscles of the hand include 20 muscles outside the hand and include long flexors and extensors of the wrist and fingers, the pronators, and the supinator. 2. a muscle that links a limb to the trunk of the body.
