Organization of sensory neurons to the muscles of mastication in the cat.

The sensory neurons in the trigeminal ganglion which project to the muscles of mastication of the cat were studied using the retrograde transport of horseradish peroxidase. Horseradish peroxidase either was injected directly into the masticatory muscles or applied to the nerves supplying them. Numerous retrogradely labeled neurons were found in the ipsilateral trigeminal ganglion. All labeled neurons were sequestered within the posterolateral (mandibular) portion of the ganglion, but the ganglion cells innervating individual muscles were not organized topographically. The diameter of the labeled neurons varied greatly and included profiles considered small, medium and large. The organization of the neurons in the trigeminal mesencephalic and trigeminal motor nuclei which project to individual masticatory muscles also was noted. It is suggested that many of the ganglion cells of small and medium size may be important for the perception of muscle pain from the masticatory muscles in the cat.