A Study of Muscular Atrophy after Tenotomy and Denervation Single Fiber Electromyography and Tissue

To study atrophic muscles after tenotomy and denervation, we used as subjects leghorn superficial pectoral muscle (type II fiber muscle), and examined changes in Single Fiber Electromyography (SFEMG) and tissue for four weeks. The amplitude of SFEMG gradually decreased, the duration became prolonged, and waves like those of type I fibers were found with an amplitude of less than 2.4 mV and a duration of over 2 msec. The amplitude was smaller in denervated muscle than in tenotomized muscle. The duration of the tenotomized muscle was more uneven than that of denervated muscle. Histological findings (ATPase stain) showed that the muscle fibers gradually atrophied and that the type of muscle fibers did not change. Although SFEMG showed that tenotomy and denervation caused type II fibers to change in to type I fibers, histological findings showed no change