Morphological peculiarities of the trigeminal nerve roots and ganglia in human fetus

The study of the intracranial traject of the trigeminal nerve was performed through a dissection of 40 human fetuses whose ages ranged between 4 and 9 months. We examined: the apparent origin of the nerve, the traject, stating the length and width of the roots and of the triangular plexus, the antero-posterior width of the trigeminal ganglion and its transverse diameter, measured between the two extremities (horns). The anatomical landmarks were considered left versus right for each fetus and the trigeminal ganglia were studied only in terms of macroscopy: form and relations. We found that the sensory root length increases greatly between the fourth and the fifth month (more than 1 mm), from six to seven months the root length present a stagnation and in the eighth month its increase in length is very significant, about 4 mm, while in the ninth month we also recorded an increase of about 2 mm. The motor root may have two separate fiber bundles, both as cylinders, which can be present from the apparent origin and up to the mandibular nerve; near their origin of the two bundles are separated by nervous tissue. The trigeminal ganglia has, most often, a semilunar aspect, thus justifying its name. Other times it may be irregular, triangular or quadrilateral (rectangular). There are situations when the trigeminal ganglion shows three lobes, each corresponding to one of its three terminal branches.