Applied anatomy of tentorial notch of cerebellum

Objective:To provide anatomic data for imaging diagnosis and surgical treatment of the diseases of tentorial notch region.Methods:We studied the neurovascular course of tentorial notch region and the adjacent relationships between the tentorial notch and surrounding structures through the microdissection of tentorial notch region afforded by the median infratentorial-supracerebellar approach in 16 cadaveric embalmed heads and using 10 series cranial transverse sections and the MR images of 5 adult healthy volunteers.Results:Great cerebral vein,basal vein and posterior cerebral artery coursed within the superior part of tentorial notch.The parahippocampal gyrus was adjacent laterally to tentorial notch.The trochlear nerve,superior cerebellar artery,posterior cerebral artery,anterior choroidal artery,precentral cerebellar vein and basal vein coursed through the middle part of tentorial notch.The trochlear nerve and superior cerebellar artery coursed inferiorly and medially to the free margin of tentorial notch,however,posterior cerebral artery coursed superiorly and medially to the free margin of tentorial notch from anterior to posterior.The parahippocampal gyrus and uncus was adjacent laterally ro tentorial notch.There were trochlear nerve,basal artery and superior cerebellar artery and its branches within the inferior part of tentorial notch.The parahippocampal gyrus,uncus and the amygdaloid body situated the deep of uncus were adjacent laterally to tentorial notch.Conclusions:The tentorial notch closely contacts with oculomotor nerve,trochlear nerve,posterior cerebral artery and superior cerebellar artery.The trochlear nerve is a very delicate structure that can be easily injured during the exposure of the tentorial notch.The cerebello-mesencephalic segment of the superior cerebellar artery is the good landmark to identify the trochlear nerve that situated within the middle part of tentorial notch.The uncus and the medial part of the parahippocampal gyrus herniate medially and downward through the tentorial incisura,easily causing oculomotor nerve,midbrain and superior cerebral artery compression.