CYTOARCHITECTONIC STUDY OF THE TRIGEMINAL GANGLION IN HUMANS

Abstract

The trigeminal ganglion (TG), a cluster of pseudounipolar neurons, is located in
the trigeminal impression of the temporal pyramid. It is covered by a sheath of the dura
mater and arachnoid and is near the rear end of the cavernous sinus. The peripheral
processes of the pseudounipolar cells are involved in the formation of the first and
second branch and the sensory part of the third branch of the fifth cranial nerve, and
the central ones form the sensory root of the nerve, which penetrates at the level of the
middle cerebellar peduncle, aside from the pons, and terminate in the sensory nuclei of
the trigeminal complex. We found that the primary sensory neurons involved in sensory
innervation of the orofacial complex are a diverse group. Although they possess the
general structure of pseudounipolar neurons, there are significant differences among
them, seen in varying intensities of staining. Based on our investigations we classified
the neurons into 7 groups, i.e. large, subdivided into light and dark, medium, also
light and dark, and small light and dark, and, moreover, neurons with an irregular
shape of their perikarya. Further research by applying various immunohistochemical
methods will clarify whether differences in the morphological patterns of the neurons
are associated with differences in the neurochemical composition of various neuronal
types.