A study of nerve-muscle relations and fine innervation patterns is reported for the stapedius muscle of the cat. Gross relations of the muscle to its associated nerves and other middle ear structures are shown by illustrations. Histologic features of innervation are studied with the Bodian silver method. the thiocholine technique, and iron hematoxylin and osmic acid stains.

The muscle is richly supplied by 3 to 4 facial nerve branches in which no axons are found above 8 μ and the majority are unimodally grouped at 2–4 μ. The auricular nerve of the vagus does not penetrate the muscle. Three to four distinct zone is of fasciculi are found whose muscle fibers are 14–20 μ in diameter. Each zone is supplied by primary nerves whose branches do not exhibit terminal overlap or multiple innervation of muscle fibers. Short terminal axons lead to motor and plates from all intramuscular nerve branches. Nerve branches and motor end plates are confined to the basal third of the muscle. Sensory endings are not detected within the muscle or its tendon. It is estimated that each motor neuron supplies no more than five muscle fibers but more probably three or less.