ROLE OF PROPRIOCEPTORS IN THE MYLOHYOID MUSCLE

Afferent discharges of the mylohyoid muscle branch during respiration were studied electrophysiologically in the rat. Afferent discharges fr om the mylohyoid muscle branch of the mylohyoid nerve were found to be synchronized with respiration. Stretching of the mylohyoid muscle eli cited afferent discharges of the mylohyoid muscle branch, suggesting t hat lengthening of the mylohyoid muscle caused electrical activity in the proprioceptors. When the central cut end of the mylohyoid muscle b ranch was stimulated electrically, reflex discharges were recorded fro m the EMG lead at the sternohyoid muscle where it is innervated by the cervical nerve. The latency between the electrical stimulation and th e action potential in the sternohyoid muscle was 3-4 ms. Therefore, th e mylohyoid muscle branch may transmit information to the sternohyoid muscle regarding the stretching actions of the mylohyoid muscle result ing from movements of the hyoid bone.