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Rotenstreich L, Eran A, Siegler Y, Grossman R, Edery N, Cohen R, Marom A. Unveiling the vulnerability of the human abducens nerve: insights from comparative cranial base anatomy in mammals and primates. Front Neuroanat 2024; 18:1383126. [PMID: 38741761 PMCID: PMC11089250 DOI: 10.3389/fnana.2024.1383126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 04/11/2024] [Indexed: 05/16/2024] Open
Abstract
The topographic anatomy of the abducens nerve has been the subject of research for more than 150 years. Although its vulnerability was initially attributed to its length, this hypothesis has largely lost prominence. Instead, attention has shifted toward its intricate anatomical relations along the cranial base. Contrary to the extensive anatomical and neurosurgical literature on abducens nerve anatomy in humans, its complex anatomy in other species has received less emphasis. The main question addressed here is why the human abducens nerve is predisposed to injury. Specifically, we aim to perform a comparative analysis of the basicranial pathway of the abducens nerve in mammals and primates. Our hypothesis links its vulnerability to cranial base flexion, particularly around the sphenooccipital synchondrosis. We examined the abducens nerve pathway in various mammals, including primates, humans (N = 40; 60% males; 40% females), and human fetuses (N = 5; 60% males; 40% females). The findings are presented at both the macroscopic and histological levels. To associate our findings with basicranial flexion, we measured the cranial base angles in the species included in this study and compared them to data in the available literature. Our findings show that the primitive state of the abducens nerve pathway follows a nearly flat (unflexed) cranial base from the pontomedullary sulcus to the superior orbital fissure. Only the gulfar segment, where the nerve passes through Dorello's canal, demonstrates some degree of variation. We present evidence indicating that the derived state of the abducens pathway, which is most pronounced in humans from an early stage of development, is characterized by following the significantly more flexed basicranium. Overall, the present study elucidates the evolutionary basis for the vulnerability of the abducens nerve, especially within its gulfar and cavernous segments, which are situated at the main synchondroses between the anterior, middle, and posterior cranial fossae-a unique anatomical relation exclusive to the abducens nerve. The principal differences between the pathways of this nerve and those of other cranial nerves are discussed. The findings suggest that the highly flexed human cranial base plays a pivotal role in the intricate anatomical relations and resulting vulnerability of the abducens nerve.
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Affiliation(s)
- Liat Rotenstreich
- Laboratory for Anatomy and Human Evolution, The Farkas Family Center for Anatomical Research and Education, Rappaport Faculty of Medicine, Department of Neuroscience, Technion – Israel Institute of Technology, Haifa, Israel
| | - Ayelet Eran
- Laboratory for Anatomy and Human Evolution, The Farkas Family Center for Anatomical Research and Education, Rappaport Faculty of Medicine, Department of Neuroscience, Technion – Israel Institute of Technology, Haifa, Israel
- Neuroradiology Unit, Department of Radiology, Rambam Medical Center, Haifa, Israel
| | - Yoav Siegler
- Department of Obstetrics and Gynecology, Rambam Medical Center, Haifa, Israel
| | - Rachel Grossman
- Department of Neurosurgery, Rambam Medical Center, Haifa, Israel
| | - Nir Edery
- Department of Pathology, Kimron Veterinary Institute, Bet Dagan, Israel
| | - Roni Cohen
- Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Assaf Marom
- Laboratory for Anatomy and Human Evolution, The Farkas Family Center for Anatomical Research and Education, Rappaport Faculty of Medicine, Department of Neuroscience, Technion – Israel Institute of Technology, Haifa, Israel
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Ma C, Zhu X, Chu X, Xu L, Zhang W, Xu S, Liang L. Formation and Fixation of the Annulus of Zinn and Relation With Extraocular Muscles: A Plastinated Histologic Study and Its Clinical Significance. Invest Ophthalmol Vis Sci 2022; 63:16. [DOI: 10.1167/iovs.63.12.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Chunjing Ma
- Department of Anatomy, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Xingyu Zhu
- Department of Anatomy, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Xuan Chu
- Department of Anatomy, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
- Hefei Cancer Hospital, Chinese Academy of Sciences, Hefei, China
| | - Liu Xu
- Department of Anatomy, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Wei Zhang
- Department of Anatomy, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
- Human Brain Tissue Resource Center, Anhui Medical University, Hefei, China
| | - Shengchun Xu
- Department of Anatomy, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
- Human Brain Tissue Resource Center, Anhui Medical University, Hefei, China
| | - Liang Liang
- Department of Anatomy, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
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Yağmurlu K. Editorial: Neurosurgery and Neuroanatomy. Brain Sci 2022; 12:brainsci12030341. [PMID: 35326297 PMCID: PMC8946273 DOI: 10.3390/brainsci12030341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 02/28/2022] [Indexed: 11/16/2022] Open
Abstract
Microsurgical anatomy is not only the backbone for neurosurgical operations, but also for technological innovations, novel surgical techniques, a better understanding of the etiopathogenesis of pathologies, and translational medicine from neuroscience to daily clinical practice [...]
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Affiliation(s)
- Kaan Yağmurlu
- Department of Neurological Surgery and Neuroscience, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
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