Distortion of mandibular kinesthesia induced by vibration of human jaw muscles

Kinesthetic experience accompanying vibration of human jaw muscles was investigated in 12 healthy subjects. Vibration of the masseter muscle with the jaw in a 20-mm opened position caused the subjects either to underestimate jaw closing effects or to experience jaw opening movements depending on whether the mandible was free to move or kept in a constant position. During vibration of the depressor muscles with the mandible in its rest position the subjects underestimated an opening movement, but fixation of the mandible caused no illusions of movement. All kinesthetic illusions perceived during vibration corresponded to elongation of the muscles under study beyond their actual length. Distortion of kinesthesia was independent of the amplitude and frequency of vibration and it persisted during anesthesia of the temporomandibular joints and loading of the mandible. It can be concluded that jaw muscle receptors may contribute to mandibular kinesthesia.