Journal of the neurological sciences
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The trigeminal ganglion, roots and the initial portion of the ophthalmic, maxillary and mandibular nerves were dissected in 3 cadavers, to study the number, area and composition of the fascicles, and the density and diameter spectra of myelinated fibers. The total number of fibers (x 1000) was 26 in the ophthalmic, 50 in the maxillary, and 78 in the mandibular division, 7.7 in the motor root and 170 in the sensory root. In all nerves, the histograms of fiber diameter had a bimodal distribution. ⋯ The findings in the three peripheral divisions agree with electrophysiological data about sensory and motor conduction in human trigeminal nerves. The observation that the ophthalmic and maxillary nerves have similar fiber spectra indicates that a special fiber composition does not account for the sparing of the ophthalmic division in trigeminal neuralgia. The absence of very large (A alpha) fibers in the sensory root does not support the view that impulses from muscle spindles are conducted along this root.