Gruber's Ligament is a Part of the Dura Mater: An Anatomical and Histological Study of Dorello's Canal Relevant to Skull Base Surgery.

Objective: Many studies have focused on Gruber's ligament and Dorello's canal. However, only scant studies have analyzed these structures via histological analysis. Furthermore, the histology studies for these structures did not sufficiently evaluate them and their surrounding anatomical relationships. Therefore, this study aims to assess the comprehensive morphology of Gruber's ligament and Dorello's canal. Materials and Methods: Histological observation in coronal and sagittal sections and microsurgical observations (using both conventional and inferior approaches) were conducted on Gruber's ligament, Dorello's canal, and related structures. Results: Histological observation revealed that the only extension of the dura was found between the petrous apex and the clivus. Microsurgical dissection using the conventional approach identified a fibrous band, whereas the inferior approach did not reveal any distinct connective tissue other than dura. Our multidirectional approach demonstrated that Gruber's ligament is part of the dura between the petrous apex and clivus. The petrous apex end was artificially separated from the dura along the medial wall of the cavernous sinus. The previously reported variations of Gruber's ligament, such as duplication or absence, can now be explained by our findings. Conclusion: Gruber's ligament is simply a part of the dura at the skull base. The extension of the dura between the petrous apex and clivus, which forms part of a mesh-like structure rather than a distinct ligament, traditionally has been termed Gruber's ligament.