Silent period in the mentalis muscle induced by facial nerve and cutaneousstimulation

The aim of this study was to demonstrate that silent periods of the mentali s muscle are induced after facial nerve stimulation and cutaneous stimulati on in normal subjects. When the marginal mandibular branch of the facial ne rve and the cutaneous nerve in areas adjacent to the lower lip were stimula ted during slight voluntary contraction of the mentalis muscle, silent peri ods were elicited with surface electrodes on the mentalis muscle. The early phase and the late phase of the silent period were elicited by marginal ma ndibular branch stimulation. The early phase of the silent period was recog nized following the F waves and it disappeared at 36.3 msec. The average du ration of the late phase of the silent period was 59.2 msec, with an averag e latency of 62.5 msec. Only the late phase of the silent period after cuta neous stimulation could be elicited, with a duration and latency of 55.9 ms ec and 54.0 msec respectively. The authors conclude that the silent period is able to be elicited in the mentalis muscle by peripheral nerve stimulati on, and is one of the late responses in facial muscles.