Mechanical contraction property of the levator veli palatini muscle.

Twenty adult dogs anesthetized with sodium pentobarbital were used as experimental animals in an analysis of the mechanical contraction properties of the levator veli palatini muscle. The following results were obtained: the contraction time and half relaxation time of maximal isometric twitch of the muscle were revealed to be 43 msec and 33 msec, respectively; a summation curve was obtained with stimulation at 15 Hz and maximal tetanic tension was at 70 Hz. The average of the tetanic tension ratio was found to be 5.7. The maximum rate of tension rise was observed at 150 Hz, and the value was twice the rate of the twitch contraction. The duration time of the active state plateau showed values of 3.9 to 4.5 msec. The contraction time of the levator veli palatini muscle closely resembles that of the intrinsic laryngeal and the orbicularis oris muscle.