The term proprioception was introduced by Sherrington, who defined it as a reflex system for the maintenance of body position and coordination of movement and the means whereby one is conscious of body position. The subject of proprioception was an integral part of his brilliant work in elucidating the spinal reflexes in the course of which he described reciprocal innervation and explained the myotatic reflex (Sherrington, 1893 and 1906). He observed that normal movement of limbs is no longer possible when the dorsal roots of spinal nerves are severed and attributed the ataxic movements to loss of sensory feedback (as one would call it now) from the muscles. Muscle receptors, through their reflex activity, are therefore essential for the fine adjustment and maintenance of posture and they act as antigravity receptors in regulating the flexion of joints. When Sherrington first referred to proprioception, Golgi tendon organs were a recent discovery but there was already a large literature on muscle spindles and his experiments provided the first clear evidence of their function.