Introduction: The hypoglossal canal (HGC) is the most important structural landmark for the endoscopic endonasal approach to access the lower clivus (LC). We explored the feasibility of using the tough fibrous tissue covering the supracondylar groove (SCG) as a useful landmark to identify the location of the HGC.
Methods: Four cadaveric specimens were dissected and analyzed. The craniovertebral junction (CVJ) region was accessed utilizing a 4-mm endoscope with either 0° or 30° lenses. CVJ exposure and the surgical corridor areas were measured. The relationship between the tough fibrous tissue covering the SCG and the HGC was analyzed.
Results: Tough fibrous connective tissue was tightly attached the SCG and ran superomedially to inferolaterally. The angle between the horizontal plane and the long axis of the SCG was 30°. Separating the tough tissue inferolaterally, we could locate the external orifice (EO) of the HGC to further accurately isolate the hypoglossal nerve.
Conclusions: The tough fibrous connective tissue covered the SCG to the upper part of the HGC EO. The course of the tough fibrous connective tissue was superomedial to inferolateral. Using the tough fibrous connective tissue covering the SCG as a landmark, it was possible to accurately locate the HGC EO via the endoscopic endonasal approach to access the LC.
Patient Care: The tough fibrous connective tissue attached the SCG points to the upper part of the HGC EO. The course of the tough fibrous connective tissue is superomedial to inferolateral. The SCG tough fibrous connective tissue can be used as a landmark to accurately locate the upper part of the HGC EO when performing endoscopic endonasal approaches to access the LC.
Learning Objectives: The tough fibrous connective tissue attached the SCG points to the upper part of the HGC EO. The course of the tough fibrous connective tissue is superomedial to inferolateral. The SCG tough fibrous connective tissue can be used as a landmark to accurately locate the upper part of the HGC EO when performing endoscopic endonasal approaches to access the LC.