THE SHEATHS OF THE 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 t he so-called cavernous sinus lateral wall anatomy. Special attention h as 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 adu lt and cadaveric micro-dissections (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 lod ge up to the anterior cliniod process for the oculomotor nerve. Howeve r, the remaining distal portion of these nerves are embedded in a peri pheral sheath. Conversaly, the meninges of the Meckel's cave stop at t he 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 superi or walls of the lodge, around the trigeminal ganglion, near the oculom otor, throchlear and ophtalmic nerves explains the location of meningi omas in these areas. These anatomical findings could provide the basis for a classification of meningiomas of the cavernous sinus and help t he surgeon to preverve the uninvolved cranial nerves.