Petroclival Clinoidal Folds and Relationships with Arachnoidal Membranes of Anterior and Middle Incisural Spaces: Old Neuroanatomical Terms for a New Neurosurgical Speech in Cadaver Labs with Limited Resources Era. Part II: Free Edge of the Tentorium, Petroclinoid Folds, and Incisural Spaces.

BACKGROUND Anatomical dissections play an irreplaceable role in the training of new generations of effective neurosurgeons, especially when addressing skull base lesions is required.The Authors describe an inter-laboratory dissection study aimed at improving the knowledge of a complex region of the skull base. The anterior and middle incisural spaces are of remarkable anatomical and surgical interest due to complex relationships between bony, dural, arachnoidal, and neurovascular structures. The primary purposes of this study are to describe the anatomy of this region with particular emphasis on the relationships between the anterior margin of the free edge of the tentorium and the sphenoid and petrous bone; to identify surgical implications in many different types of neurosurgical procedures dealing with this challenging, complex anatomic area.METHODS Thirteen anatomical specimens, including five injected specimens, were dissected in this study. In the formalin-fixed specimens, vessels were injected with colored silicone.RESULTS The anatomical study was focused on the description of the relationships between bony dural, arachnoid, and neurovascular structures. Surgical implications are described accordingly.CONCLUSIONS Detailed anatomical knowledge of this region finds concrete applications in neurosurgical practice since the anterior and middle incisural spaces are often surgically exposed in neoplastic and vascular diseases. The high-definition pictures reported in this study could represent useful support to understand the anatomy of this complex region.Finally, our study could provide guidance to neurosurgical centers in which resources are limited that are either planning to establish their own cadaver dissection laboratory or failed to do so because of the supposed high-costs.