Proprioception is the sense of position and movement of the limbs. The sense arises through activity in sensory neurons located in skin, muscles, and joint tissues. Proprioception appears to be a compound sense, relying on simultaneous activity in a number of types of afferent neurons. Position sense is largely mediated by activity in muscle afferent neurons. Afferent neurons originating in soft tissues of the joints contribute a sense of joint position only when the joint is rotated into a limit of its range of motion. Joint neurons have an important role in protecting the integrity of joints if they are unstable. Afferent neurons in skin appear to contribute little to position sense but may contribute to the sense of movement.
Peter Grigg is with the Department of Physiology, S4-245, University of Massachusetts Medical School, Worcester, MA 01655.