Afferent fibers and sensory ganglion cells within the oculomotor nerve in some mammals and man. I. Anatomical investigations.

The present research shows that sensory ganglion cells are located within the oculomotor nerve of monkeys and man. Furthermore, afferent fibers have been found in the IIIrd nerve of all the animals examined (lamb, pig, cat, dog and monkey). These fibers have their perikarya prevalently in the semilunar ganglion. Their pathway could be studied after section of either the trigeminal ophthalmic branch or of the intracranial portion of the IIIrd nerve. Following these operations, degenerating fibers were found entering the brain stem through the oculomotor nerve. In the brain stem, they were traced through the pons and the medulla and were seen to end in the spinal cord, within the subnucleus gelatinosus of the nucleus caudalis trigemini. Their degenerating endings found in the neuropil of the SG Rolandi, represented peripheral axonal endings of the glomeruli, rather than central axonal endings, as was the case after trigeminal rhizotomy. On the basis of these different degenerating patterns, the conclusion can be reached that the perikarya of the afferent fibers located in the semilunar ganglion represent, in reality, a ganglion of the IIIrd nerve.