The Sensory and Motor Axons of the Chorda Tympani. ∗

Abstract

Summary

The intact chorda tympani of the cat contains an average of 1955 combined sensory and motor axons; whereas, a total of 3347 sensory and motor nerve fibers is found in the normal chorda tympani of the dog (Table I).

An average of 1157 sensory axons remains in the chordae tympani of the cat and 2205 sensory nerve fibers persist in the chorda tympani of the dog after the preganglionic motor axons are eliminated from the chorda tympani by cutting them in the facial nerve central to the geniculate ganglion.

It is estimated that the chorda tympani of the cat has, on the average, 798 motor nerve fibers in it. Approximately 1142 motor axons are present in the chorda tympani of the dog.

The majority of the motor and sensory axons in the chorda tympani of both the cat and dog belong to the myelinated variety of nerve fiber. In the cat an average of only 18% of the sensory nerve fibers and 20% of the motor axons is without myelin sheaths. In the chorda tympani of the dog 23% of the sensory axons was unmyelinated while just 6% of the motor axons was without myelin sheaths.