Intracranial Anatomical Triangles: A Comprehensive Illustrated Review

Abstract

There are multiple anatomical triangles of the skull base. However, to our knowledge, there has been no comprehensive review of these geometric landmarks. To allow for a safe and consistent approach to lesions of the skull base such as those near the internal carotid artery, internal acoustic meatus, and cavernous sinus, a comprehensive review of the variations with illustrations is required. This article provides an overview of the anatomical borders, dimensions, and surgical implications as well as illustrations of the major skull base triangles.

Microsurgical Anatomy of the Inferomedial Paraclival Triangle: Contents, Topographical Relationships and Anatomical Variations

“…The inferomedial triangle is a space in the posterior wall of the cavernous sinus. Several anatomical structures of surgical importance are located within it [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. Its superior border involves the posterior petroclinoid dural fold [ 1 , 2 , 3 , 4 ].…”

“…According to Tomio et al [ 23 ], the petrosphenoidal ligament is visible in most adults. However, it can also be hypoplastic (rudimentary), ossified or even absent [ 6 , 8 , 12 , 24 ]. In our series, the ligament was hypoplastic in 15.2% of cases and absent in 4.3%.…”

“…According to the classical description by Dolenc [ 1 ], it is delineated by the posterior clinoid process (the medial point of the triangle), the dural entrance of the trochlear nerve (the superolateral point) and the dural entrance of the abducens nerve (the inferolateral point). The main contents of this triangle include such anatomical structures as the dura forming the posterior wall of the cavernous sinus, the abducens nerve (typically located in Dorello’s canal under the petrosphenoidal ligament), the petrosphenoidal (Grüber’s) ligament, the posterior genu of the internal carotid artery’s intracavernous segment and the dorsal meningeal artery, which is typically a branch of the meningohypophyseal trunk [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Rhoton [ 2 ] stated that removing the medial half of the triangle exposes the lateral edge of the dorsum sellae and the upper end of the petroclival suture.…”

“…There are few detailed descriptions of the normal anatomy of the triangles around the cavernous sinus in the literature, and only the typical arrangement of structures within each triangle is generally shown [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. A new approach to understanding the triangles around the cavernous sinus addressing the locations and positions of the structures and their three-dimensional relationships was proposed by Chung et al [ 10 ].…”

Morphometry of Glasscock’s Triangle Pertinent to the Exposure of Horizontal Intrapetrosal Segment of the Internal Carotid Artery

“…It has been quoted that there are around 10 different triangles around the CS. [1][2][3][4] Watanabe classified the triangles in three subregions-the parasellar group (anteromedial, paramedial, oculomotor, and superolateral), the middle cranial fossa group (anterolateral, posterolateral, and posteromedial), and the paraclival group (inferomedial and inferolateral). 4 Out of the plethora of specific anatomical triangles (regions) around the CS, one of them is posterolateral triangle-the Glasscock's triangle (GT).…”