[Peculiarities of the innervation of some muscles in the oto-rhino-laryngological region].

Abstract

This study shows different aspects of the innervation of some striated muscles. It appears that neuromuscular spindles are not present in all skeletal muscles. Some muscles of the oto-rhino-laryngological region lack spindles whilst their direct antagonists possess them. Amongst the muscles of the external and middle ear, the soft palate and the larynx having opposite actions, there is in each case one muscle which does not have any spindles. These muscles then have only motor innervation. The muscles which have neuro-muscular spindles are innervated by nerves composed of extra- and intrafusal motor fibres and proprioceptive fibres. The neuro-muscular spindles play a servo-braking role in the muscle where they occur. The oppose then a certain passive elongation of the muscle. At the same time and in this manner, they contribute in controlling and restraining the action of the muscles or of their opponents. This role is particularly important for the various muscles of the oto-rhino-laryngological region and is all the more important since the amplitude of the movements which they cause is very weak. The presence of these spindles increases also the sensitivity and the delicacy of the desired movement, for the behaviour of these muscles is very special. (See formula in text).