3 - Variations in the Branching Pattern of the Obturator Nerve with a Focus on the Branches of the Common Trunk; Does the Nerve Occasionally Innervate Obturator Internus?

Poster Board Number: 3
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Odd poster #s – first hour
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Abstract Body :
Introduction & Objectives: The obturator nerve is one of the important nerves of the thigh. It takes origin from the lumbar plexus, passes along the lateral pelvic wall, and then courses in the superior medial compartment of the thigh by passing through the obturator foramen. The nerve along with its divisions gives many branches throughout its course. Though the branches of the divisions have been well documented, the branches of the trunk of the obturator nerve and their fate remain underrepresented. A study was done last year to understand the branching pattern of the obturator nerve. This year’s study was done as a continuation of the previous study and to answer the question if the obturator nerve occasionally supplied the obturator internus muscle. Materials and Methods: 22 formalin-fixed cadavers were dissected to observe the course and branches of the right obturator nerve in the pelvic cavity and the superior medial compartment of the thigh. The obturator foramen was opened by taking out part of the superior pubic ramus and the course of the common trunk of the nerve and its branches was examined. Results: In 81.81% (18/22) of the bodies, the common trunk of the obturator nerve gave at least one branch before entering the obturator foramen. The branches from the trunk when present supplied the obturator externus muscle and the hip joint in 50% (11/22) cases and supplied only the muscle in the rest 31.81% (7/22) of the cases. Occasionally, the branch supplied the neighboring blood vessels. It was also noticed that the obturator nerve gave a branch to the hip joint in 86.3% (19/22) cases. The previous observation that the nerve occasionally supplied obturator internus muscle seemed erroneous and after following the branches to their termination, it was observed that they did not supply obturator internus despite the nerve’s course through the muscle. Conclusion: The study confirmed the high anatomic variability of the branches of the obturator nerve. The fate of each of these branches is also highly variable. The nerve supplied obturator externus and all the muscles of the adductor compartment, occasionally supplying pectineus, but it did not innervate obturator internus. Significance: This study improves our understanding of the role of the obturator nerve in the innervation of the hip joint. These variations may be relevant to the development of therapies to address injury of the obturator nerve at the pelvic brim. The author thanks the individuals who donated their bodies and tissues for the advancement of education and research, which were provided by the UC Anatomical Materials Programs.