The oculomotor nerve in the cavernous sinus and orbit

Abstract

The pathway of the oculomotor nerve in the human cavernous sinus and orbit was examined with serial sections. The oculomotor nerve separates into the superior and inferior division at 4.5 mm within the cavernous sinus before the orbital apex. After subdividing of the superior division, the inferior division persists as a single funiculus up to about 5 mm from the orbital apex. Fiber count of the superior division is one third of that of the inferior division. Therefore, the inferior division seem to be more resistant than the superior division. From these results the authors suggest that relative pupil sparing in cavernous sinus and orbital lesions of the oculomotor nerve reflects sparing of the inferior division.