The Petroclinoid Ligament: Its Morphometrics, Relationships, Variations, and Suggestion for New Terminology

Abstract

The anatomy and definition of the petroclinoid ligament (PCL) and its relationship with the abducens nerve are variably described. The goal of this study was to clarify the anatomy of the PCL and better elucidate its relationship with the abducens nerve. Thirty-six sides from 18 fresh-frozen adult cadaveric heads were used in this study. Specimens were all Caucasian and derived from 10 males and 8 females. The mean age at death was 79 years. Dissection of the PCL and abducens nerve was performed using a surgical microscope. The anterior and posterior attachments of the PCL, and position of the abducens nerve were noted. Subsequently, the width, thickness, and length of the ligament, and diameter of the abducens nerve were measured. Thirty-one sides (86.1%) were found to have a PCL, on two sides (5.6%), the PCL was ossified, and on three sides (8.3%), the PCL was absent. The width, thickness, and length of the PCL ranged from 0.54 to 3.39, 0.07 to 0.49, and 3.27 to 17.85 mm, respectively. No PCL had an anterior attachment onto the posterior clinoid process but rather, the clivus. Therefore, based on our findings, the PCL would be better described as the petroclival ligament.

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

“…The petrosphenoidal ligament (also known as Grüber’s ligament, the superior sphenopetrosal ligament or the petroclival ligament) is a useful surgical landmark for the abducens nerve [ 8 , 12 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. However, the nomenclature for Grüber’s ligament has been inconsistent in reports in the literature, and some authors used the term petroclinoid ligament instead of the petrosphenoidal ligament [ 1 ].…”

“…A recent study by Iwanaga et al investigated the ligament’s morphology and found that Grüber’s ligament does not attach to the posterior clinoid process but to the lateral edge of the clivus. Therefore, the term petroclival ligament should be used when describing the petrosphenoidal ligament [ 26 ]. In contrast, the petroclinoid folds are folds of the dura mater that extend between the anterior and posterior clinoid processes and the petrosal part of the temporal bone.…”

“…In a study by Icke and Ozer [ 25 ], the ligament was complete in 52% of cases and incomplete (fragmented or hypoplastic) in 38%. In one of the most recent reports, the ligament was absent in 8.3% of cases [ 26 ]. Additionally, the structural relationships between the abducens nerve’s dural covering and Dorello’s canal (both are among the contents of the inferomedial triangle) are clinically relevant; a secondary tunnel forming a “tube within a tube” is located within Dorello’s canal and exclusively contains the abducens nerve [ 27 ].…”

Review of the Petroclinoid Ligament

“…This fundamental structure has been named very differently at different moments of history. However, not all of the given names can fully describe its morphology adequately, and therefore, recent studies have proposed new nomenclature to clarify its anatomy [6].…”

“…Interestingly, the dissection showed that the PCL's anterior attachment was primarily to the upper extension of the clivus instead of to the posterior clinoid process. Therefore, the authors concluded that its current name did not accurately describe the real anatomy of the structure and proposed the term petroclival ligament [6].…”