Brain Stem 3-Dimensional Microsurgical Anatomy, Interior Architecture and Safe Entry Zones




Brainstem Anatomy, Brainstem safe entry zones, Mesencephalon, Pons, Medulla Oblongata


Objective: It is aimed to reveal the 3D microsurgical anatomy of the cranial nucleii, other gray matter assemblies and white matter tracts in the brainstem, and to identify the neighbor structures of all the safe entrance ways to the brainstem and to compare the safe entrance ways with the literature.

Materials and Method: This study was carried out at Istanbul University, Cerrahpaşa Medical Faculty Department of Neurosurgery, Micro-Endo-Neurosurgery and Neuroanatomy Education Research Laboratory. Seven cadaveric human brain stems were fixed according to Klingler J. And Ludwig E. Method and prepared for dissection. The dissections were performed with a microsurgical set under a surgical microscope. Disections were performed from the front, back and lateral. Microsurgical anatomy of brain stem was revealed. Digital photographs and 3D photographs were taken at each stage.

Results: In the literature, 18 safe entry regions were revealed with surrounding boundaries.It has been revealed for the first time in the literature that intramesencephalic fibers of the oculomotor nerve also pass through the lateral aspect of the red nucleus in the anterior mesencephalic region. It has been shown for both infracollicular entry and intercollicular safe entry zones, IV. cranial nerve is under high risk. The proximity of the vestibular nerve and the inferior cerebellar peduncle in the lateral pontin region have been documented for the first time. When moved deeper in the supratrigeminal region the medial and lateral lemniscus are encountered. The dorsolateral border of the olivary region in medulla oblongata is formed by CTT, which has not been mentioned in the literature.

Conclusion: Surgeons who deal with brain stem surgery must know brainstem anatomy with all cranial nerves, descending and ascending pathways in detail. Fiber dissection technique is the best way to gain this knowledge. Surgeons should consider to combine this information with new neuroimaging techniques, in addition to the changes in intraoperative neurophysiology and act accordingly.


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How to Cite

Taçyıldız AE, Üçer M, Aydın İlhan. Brain Stem 3-Dimensional Microsurgical Anatomy, Interior Architecture and Safe Entry Zones. J Nervous Sys Surgery [Internet]. 2023 Jul. 8 [cited 2024 Jun. 22];9(1):16-30. Available from:



Research Article