Figure 3. Evoked electromyography (EMG) (A) from multiple lower limb muscles in response to repeated electrical stimulation of guidance channel (GC) no. 8 before resection. Stimuli at arrows at bottom of record; note that stimulus artifacts can just be made out in some of the traces and are best seen in records from the lateral hamstring group. All but the tibialis anterior and abductor hallucis muscles discharge at short latency in response to each of the weak stimuli (0.25 V) used. Panel B shows spontaneous EMG caused by surgical transection of the guidance channel. The initial cut (first arrow at bottom of record) failed to transect the GC, whereas the second cut (second arrow) transected the remainder of the soft tissue passing through the GC. Each “cut” was associated with a burst of EMG from the same hindlimb muscles that responded to electrical stimulation (ie, panel A of this figure). Note the difference in time base for panels A and B. The vertical line denotes 1 mV for all records in A and B. Quads, quadriceps; Hip add, hip adductors; Lat Hams, lateral hamstring; Med Hams, medial hamstring; Tib Ant, tibialis anterior; Med Gastroc, medial gastrocnemius; Abd Hallucis, abductor hallucis.