CALIBRE SPECTRA OF MOTOR AND SENSORY NERVE FIBRES TO FLEXOR AND EXTENSOR MUSCLES

Abstract

The tibialis anticus muscle and the gastrocnemius muscle in cats were de-affer-ented or de-efferented and the number and size of motor and sensory myelinated nerve fibres to the muscles studied separately, using a histological method described by Rexed [J. Neuropathol. exp. Neurol., 1948, 7 (in press)]. No differences in fibre size were noticed between extensor and flexor. The motor nerve fibres ranged from 2-17 [mu] and were collected in 2 groups from 2-7 [mu] and 7-17 [mu], respectively. The peak of the small-sized group lay at 4-5 [mu]. and that of the large-sized group at 11-13 [mu]. The sensory nerve fibres ranged from 1-17 [mu] and were collected in 3 groups from 1-4 [mu], 4-10 [mu] and 10-17 [mu], respectively. The peaks of these groups lay in the small-sized group at 2-3 [mu], in the medium-sized group at 6-8 [mu] and in the large-sized group at 12-13 [mu].Shrinkage was not corrected for. The number of sensory fibres corresponded to half of all nerve fibres in the flexor nerve but only to a 3d of all fibres in the extensor nerve. The flexor nerve thus had a relatively larger number of sensory fibres[long dash]chiefly small fibres[long dash]than the extensor nerve. A similar difference between flexor and extensor motor fibres was less definite.