The distribution of ganglion cells and motor nerve fibers in the rat posterior cricoarytenoid (PCA) muscle were investigated morphologically. Motor nerve fibers were mainly located along the ventral surface of the muscle and entered the muscle at its middle portion to form neuromuscular contacts with individual muscle fibers. Clustered ganglion cells, on the other hand, accompanied with nonmyelinated postganglionic and small myelinated preganglionic nerve fibers, were frequently found on the dorsal side of the muscle, the opposite site of the motor nerves. A few ganglion cells entered the muscle and were occasionally distributed between muscle fibers and near the bifurcation of arterioles. Ganglion cells showed acetylcholinesterase positive reactions, suggesting parasympathetic nature. These findings suggested that intramuscular ganglion cells belong to parasympathetic category and that may play an important role in the complex function of blood vessels and muscle fibers in the PCA muscle.
