Applied Anatomy of the Trochlear Nerve in the Tentorial Lateral Region

Objective:To study the trochlear nerve in the tentorial lateral region and to determine the important clinical anatomical landmarks of these important neurovascular structures to avoid injury of trochlear nerve.Methods: Fifteen cadaveric heads(ten male,five female) without deformity and disease of adults were examined using 10 times' magnification after perfusing the arteries with red latex and the relationship of the neural structures and arteries in the tentorial lateral region were observed.Trochlear nerve length,width,thickness and the distances between the important neursovascular structures and landmarks were measured,and the results were statistically analyzed.Results: The trochlear nerve entered forward into the tentorial lateral region between the superior cerebellar artery and posterior cerebral artery,and through the free edge of subdural of oculomotor triangle.The length(6.78±1.87)mm,width (1.09±0.21)mm and thickness(0.78±0.11)mm of trochlear nerve were measured.The entrance site of trochlear nerver located at(23.24±3.18)mm posterior to anterior clinoid process,(17.57±3.26)mm posterior to the supraclinoid portion of internal carotid artery,(11.42±3.32)mm posterior to the entrance site of oculomotor nerve,(14.21±3.25)mm lateroposterior to the posterior clinoid process.Conclusion: During the operation of the tentorial lateral regional,to avoid injury trochlear nerve,the anterior clinoid process,the posterior clinoid process,the supraclinoid portion of internal carotid artery,the entrance site of oculomotor nerve can be used as important symbols to find out the trochlear nerve.Meanwhile,it is important to distinguish the superior cerebellar artery and posterior cerebral artery.