Anatomy study of the superior petroclival region

Objective To observe and measure the anatomical relationship of nerves and arteries to adjacent structures in the petroclival region. Methods The nerves and arteries were anatomized and measured under microscope via retrosigmoid and presigmoid approaches for their distribution, course and anatomical relationship to adjacent structures in 10 cadaveric specimens (20 sides). Results Meckel cave contained the trigeminal ganglion and trigeminal cistern, and the width and height of the cave's opening were 8.3±1.2 mm and 5.0±1.0 mm respectively. The cisternal segment lengths of the oculomotor nerve, trochlear nerve, trigeminal nerve, abducent nerve and facial nerve were 18.8±2.8, 35.9±3.1, 12.8±1.7, 17.5±1.9 and 13.2±2.2 mm respectively. The mean distance from the point where the trochlear nerve enters into the edge of tentorium cerebelli to the oculomotor nerve was 5.4 mm (ranged 4.2 to 6.8 mm). The inferior petrosal sinus located at the middle of the cranial nerve Ⅸ and Ⅹ in 14 sides, between Ⅹ and Ⅺ in 2 and at the petrosal part of the jugular foramen or the internal jugular vein in front of cranial nerves Ⅸ in 4. Conclusion The complexity of the structure of the nerve and blood vessel in the petroclival region, familiarity with the anatomic relationships in the region may help to protect the nerve and vessel in the surgery and reduce surgical complications.