Morphometric study of the meningeal sheath of the oculo motor nerve in the latero-sellar lodge: Neuro surgical interest

Abstract

The meningeal sheath of the oculomotor nerve is also known that the latero-sellar lodge. It has both dural and extra-dural components. This sheath  contains vascular elements including the carotid and nervous siphon, the motor nerves of the eye to which are added the division branches V1 and V2 of the trigeminal nerve. The oculomotor nerve runs through this lodge wrapped in its meningeal sheath. The purpose of this study was to document the dimensions of the different segments of the nerve as it crosses the lodge. Eight pairs of lodges were the subject of this study. Dead bodies fixed with 10% formalin for two to three weeks underwent a craniotomy. After removal of the brain, nerve III and its meningeal envelope were dissected and exposed. The different segments of the nerve were measured in both sides. The entrance orifice of the porus of the oculomotor nerve III was located behind the anterior clinoid process to 7.2 mm (extreme from 3 to 13mm) on the right and to 7.40mm (extreme from 4 to 12) on the left. The meningeal cul-de-sac represented the intra-conical segment and was either 5.2mm long (extreme from 4 to 6.5mm) or short 3.25mm (extreme from 2 to 3.5mm). The supra-cavernous segment measured on the right 5.2 mm (extreme from 2 to 8 mm) and on the left 4.6 mm (extreme from 3 to 7 mm). The latero-sellar lodge, a complex and narrowed region is crossed by nervous elements each in its meningeal sheath. This deserves an approach by surgical microdissection.

Key words: Oculomotor nerves - meningeal cone - measurement – cadaver – latero-sellar lodge.