The composition of the medial articular nerve to the knee in the dog.

Light and electron microscopy were used to characterise the medial articular nerve to the knee in the dog, in terms of the total number of myelinated axons, the frequencies of different diameters of myelinated axons, the number of unmyelinated axons, and the ratios of unmyelinated to myelinated axons. Approximately 70% of all myelinated axons were of less than 5 micron diameter and, with the exception of two of sixteen nerves examined by light microscopy, all distributions were unimodal. The distributions of the two nerves of other than unimodal distribution were each characterised by a second, small peak of axon diameters ranging between 9 and 14 microns. Unmyelinated axons counted in five nerves suggested that approximately 72% of all axons of a given nerve were unmyelinated, giving a ratio of about 2.5 unmyelinated to 1.0 myelinated axon.