[Sheaths of cranial nerves in the lateral wall of the cavernous sinus. An embryological and anatomical study].

The present study has been carried out in order to better understand the so-called cavernous sinus lateral wall anatomy. Special attention has been drawn at the sheaths of the cranial nerves running through it. Serial sections of the parasellar region of four human embryos (7, 10, 11, 12 week-old), two fetuses (14 week-old and 7 month-old), one adult and cadaveric microdissections (14 cavernous sinus) have been used. We could observe that the oculomotor and the trochlear nerve possess meningeal sheaths, which accompany the nerves into the parasellar lodge up to the anterior clinoid process for the oculomotor nerve. However, the remaining distal portion of these nerves are embedded in a peripheral sheath. Conversely, the meninges of the Meckel's cave stop at the trigeminal ganglion, its branches have only peripheral sheaths and are located, as the venous system, in an "interperiosto-dural space". The presence of arachnoid granulations into the lateral and superior walls of the lodge, around the trigeminal ganglion, near the oculomotor, trochlear and ophthalmic nerves explains the location of meningiomas in these areas. These anatomical findings could provide the basis for a classification of meningiomas of the cavernous sinus and help the surgeon to preserve the uninvolved cranial nerves.