INNERVATION RATIOS FOR LARGE AND SMALL LIMB MUSCLES IN BABOON

The innervation ratio has been calculated for the abductor pollicis brevis muscle in the hand, and for the medial head of the gastrocnemius muscle in the leg of the baboon. The data presented includes results of the total myelinated nerve fibre counts in the intact, de‐afferented and de‐efferented muscle nerves. The innervation ratio for each muscle has been calculated from the number of large efferent nerve fibres in the muscle nerve, and the total number of muscle fibres present in the muscle. It was calculated that there were 43 motor units in the abductor pollicis brevis muscle and 292 in the medial head of the gastroenemius muscle. The mean number of muscle fibres per motor unit was approximately 220 in the former muscle and 790 in the latter. The calculation was complicated by the inability to section the muscle nerve above the level of axon branching, and by the difficulties encountered in attempting to produce complete de‐afferentation of the muscle. Copyright © 1969 The Wistar Institute Press