The Morphometrical Evaluation of the Localizations of Oculomotor, Trochlear, Trigeminal and Abducent Nerves in the Sphenopetroclival Region: A Microanatomical Study

Objective: The sphenopetroclival region (SPCR) and cavernous sinus are among the most difficult-to-access areas in the surgery of the skullbase due to the narrow operation corridors and its proximity to eloquent and important neurovascular structures. Oculomotor (CN3), trochlear (CN4), trigeminal (CN5) and abducent (CN6) nerves can be traumatized during the approaches because of their localizations in the SPCR. The aim of our study is to determine the relative localizations of CN3, CN4, CN5 and CN6 in SCPR Methods: On 20 basis cranii, which were obtained from adult human cadavers fixed in formaline, the entrance points of CN3, CN4, CN5 and CN6 into the dura mater of the cavernous sinus (CS) were dissected under Carl Zeiss OPMI. The distances between the entrance points of the CNs to dura mater and the distances between the CNs and the PCP were measured. Results: The mean distances between the entrance points of CN3, CN4, CN5 and CN6 to the dura mater of CS were measured as, CN3 to the CN4 2.94 +/- 0.91 mm, CN4 to the CN5 4.59 +/- 2.04 mm, CN5 to the CN6 6.50 +/- 1.74 mm. The minimum distance values of CN3 and CN4 to the PCP was 1,69 mm and 3,82 mm, respectively. Conclusion: During the surgical approaches, conserving the eloquent neurovascular structures in the SPCR is important with regard to postoperative complications. The data revealed in our study may help in determining a safe approach in SPCR surgery.