ウサギ顔面神経構成線維に関する定量的解析

抄録

Recovery of the orbicularis oculi muscle is often slower than that of the orbicularis oris muscle in patients with idiopathic facial nerve palsy. This difference is considered to depend on anatomical or physiological differences of these muscles and their innervating nerve fibers, but there has been little discussion of this problem.
Myelinated nerve fibers innervating the orbicularis oris and the orbicularis oculi muscles, from the buccal branch and zygomatic branch of a rabbit were analyzed quantitatively. After complete dissection of the facial nerve, the nerve branch to be taken as a sample was decided with the use of electrostimulation. Cross sections of the nerve were examined microscopically, and magnified photographs (×500) were studied with an image analyzer. Histograms showed larger fibers in the zygomatic branch than in the buccal branch. The mean value and standard deviation of diameter of nerve fibers in the zygomatic branch and buccal branch were 10.6±2.7μm and 7.6±2.7μm, respectively a statistically significant difference.
These findings suggest that the delay in recovery of the paralyzed orbicularis oculi muscle might be due to the difference in diameter of the zygomatic and buccal branch nerve fibers.