A Skull Base Surgeon's GPS: 27 Anatomical Triangles of the Anterior, Posterior and Middle Fossae

Procedures at the skull base are technically challenging and demand a thorough knowledge of anatomy. Anatomical triangles created by the natural intersection of nerves and vessels have been described to guide the surgeon during delicate dissections along the skull base. These geometrical corridors improve the safety of approach by orientating the surgeon in the operative field, helping to locate the lesion, and protecting critical structures, such as cranial nerves and vasculature. Review of the literature identified 27 anatomical triangles of the skull base. The eight anterior fossa triangles include: interoptic triangle, carotid–oculomotor triangle, optic–carotid triangle, supracarotid–infrafrontal triangle, oculomotor–tentorial triangle, precommunicating triangle, junctional triangle, and falcofrontal triangle. The 14 middle fossa/cavernous sinus triangles include: clinoidal/anteromedial triangle (Dolenc), oculomotor/medial triangle (Hakuba), supratrochlear/paramedian triangle, infratrochlear triangle (Parkinson), Anteromedial Triangle (Mullan), Anterolateral Triangle, Posterolateral Triangle (Glasscock), Posteromedial Triangle (Kawase), inferolateral triangle, inferomedial triangle, superior petrosal triangle, parapetrosal triangle, parasellar triangle, and internal carotid artery triangle. The five posterior fossa triangles include: vagoaccessory triangle, suprahypoglossal triangle, infrahypoglossal triangle, Trautmann's triangle/retromeatal trigone, and Guillain–Mollaret Triangle. Our goal was to create a comprehensive review of skull base triangles, with borders, contents and surgical applications, to increase anatomical knowledge and inform microsurgical dissection.