The [[posterior fossa tumor]]s can be situated either [[dorsal]] and [[lateral]], [[ventral]] and [[medial]], or occupying both [[region]]s in relation to the [[cranial nerve]]s, with the latter position being especially challenging. In an effort to organize neurovascular complexes contained within, anatomically based [[triangle]]s have been proposed to serve as guiding [[landmark]]s for locating critical neurovascular structures. The objectives of this study were to: (1) provide a review of historical anatomically based vascular-centric triangles of the [[posterior fossa]] based on respective neurovascular complexes; (2) introduce a more organized alternative system of triangles with the conceptualization of a projection system from superficial to deep; and (3) propose and describe two new triangles of the posterior fossa: [[Petrous-Acousticofacial triangle]] and [[Acousticofacial-Trigeminal triangle]]. Five [[cadaver]]s were studied. Neurovascular complexes were described with the use of anatomically guided cranial nerve-centric triangles, each of which was formed by cranial nerves, [[petrous bone]], [[brainstem]], [[tentorium]], and [[superior petrosal vein]]. All [[triangle]]s were measured and anatomical boundaries confirmed by [[neuronavigation]]. Two circumferential frameworks were created to correlate superficial and deep anatomy: (1) Outer circumference and (2) Inner circumference. Posterior fossa was divided into the following: (1) Superior complex-corresponds to the sub-[[asterion]]al region, which was projected to the [[trigeminal nerve]]; (2) Middle complex-corresponds to the [[mastoid emissary vein foramen]], which was projected to the facial and [[vestibulocochlear nerve]]s; and (3) Inferior complex-corresponds to the posterior [[condylar canal]], which projects to the [[lower cranial nerve]]s. [[Neuronavigation]] confirmed these [[landmark]]s. Two new triangles were proposed: (1) The Petrous-Acousticofacial triangle, and (2) The Acousticofacial-Trigeminal triangle. Triangles provide a useful anatomical guide to the posterior fossa. Ortiz-Rafael et al. introduced an organized schema, as well as proposed two new triangles, with the intent to minimize manipulation of neurovascular structures
((Ortiz-Rafael J, Chakravarthi SS, Revuelta-Gutiérrez R, Kassam A, Monroy-Sosa A. Microsurgical anatomy of the cranial nerve-centric triangles of the posterior cranial base: cadaveric and radiological anatomical study. Anat Sci Int. 2021 Jun 16. doi: 10.1007/s12565-021-00620-z. Epub ahead of print. PMID: 34132987.)).