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

Grzegorz Wysiadecki,Michał Polguj,Maciej Radek,R Shane Tubbs,Piotr Brzeziński,Jerzy Walocha,Joe Iwanaga

doi:10.3390/brainsci11050596

Abstract

The inferomedial triangle is one of the two surgical triangles in the paraclival subregion of the skull base. It is delineated by the posterior clinoid process, the dural entrance of the trochlear nerve and the dural entrance of the abducens nerve. The aim of the present article is to describe the anatomical variations within the inferomedial triangle. Measurements of the triangle’s borders and area were supplemented by detailed observations of the topographical anatomy and various arrangements of its contents. Nine adult cadaveric heads (18 sides) and 28 sagittal head sections were studied. The mean area of the inferomedial triangle was estimated to be 60.7 mm2. The mean lengths of its medial, lateral and superior borders were 16.1 mm, 11.9 mm and 10.4 mm, respectively. The dorsal meningeal artery was identified within the inferomedial triangle in 37 out of 46 sides (80.4%). A well-developed petrosphenoidal ligament of Grüber was identified within the triangle on 36 sides (78.3%). Although some structures were variable, the constant contents of the inferomedial triangle were the posterior petroclinoid dural fold, the upper end of the petroclival suture, the gulfar segment of the abducens nerve and the posterior genu of the intracavernous internal carotid artery.

Highlights

The inferomedial triangle is one of the two surgical triangles in the paraclival subregion of the skull base
The dorsal meningeal artery was identified within the inferomedial triangle in 37 out of 46 sides (80.4%; see Figure 2, Figure 4B,C and Figure 6A)
1), who estimated theofmean area of the inferoOnlywas twoby papers gave the exact dimensions of the triangles the cavernous sinus

Summary

Introduction

The inferomedial triangle is one of the two surgical triangles in the paraclival subregion of the skull base. 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 4.0/). 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. The inferomedial triangle is adjacent to the inferolateral triangle [9]. It neighbors the oculomotor triangle located within the middle cranial fossa; the medial half of its upper border contributes to the formation of the oculomotor triangle’s posterior border [1]

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