Contraction times of the cat's tongue muscles measured by light reflection. Innervation of individual tongue muscles

The contraction times of the cat's tongue muscles were measured by recording the fine movements of their surfaces and movements of the tongue's surfaces. The recordings were made by means of a commercial, high-sensitive light reflection transducer (Fairchild FPLA 850) which could be operated without any mechanical loading of the tongue. The contraction times of the intrinsic muscles (including pars longitudinalis superior m. hypoglossi and pars longitudinalis inferior m. styloglossi) measured about 22 ms, while the extrinsic muscles were somewhat slower, around 33 ms. The data are considered in the light of the recently reported histochemical composition of these muscles. The study of the hypoglossal nerve supply to individual tongue muscles revealed that, contrary to earlier reports, the medial nerve sends branches to the intrinsic muscles not only at its distal end but during its entire course through the tongue. The transversal and vertical muscles were found to receive numerous fibers innervating small units of their muscle fibers.