Mechanoreceptors in human myotendinous junction.

The sensory-nerve-ending system of 40 myotendinous junctions of human palmaris longus and plantaris muscles was studied histologically. All the known four types of nerve endings were identified. The Ruffini corpuscles could be found in equally small numbers (one to five) in both the muscular and tendineal sites of the junction. Also the free nerve endings were distributed equally on both sites. The Pacini corpuscles were frequent in the tendineal site (six to 14), but rare in the muscular site (one to three). The Golgi tendon organs were, in turn, frequent in the muscular site (nine to 12) but rare in the tendineal site (one to four), respectively. Within the muscle and tendon parts of the junction, the distance between two mechanoreceptors was always more than 250 microns and the receptor distribution was homogeneous. Further studies are needed to give functional explanation for these anatomic findings.