Uncommon course of obturator nerve through an osseus tunnel: Clinical relevance

A unilateral variation in the course of the left obturator nerve was observed during cadaveric dissection of the pelvis and lumbar plexus. The donor was a 94‐year‐old Caucasian male died of renal and respiratory failure. Typically, obturator nerve arose from the ventral rami of lumbar spinal segments 2–4 and traveled forwards along the lesser pelvic lateral wall on the obturator internus to the obturator foramen. The variant obturator nerve descended normally anterior to sacroiliac junction continued the lateral pelvic course and entered a 6 cm long osseus tunnel in the superior rami beginning at the iliopectineal junction (close to ischial spine) and emerged to continue a normal course joined by the obturator vessels. The right side exhibited normal course. Although the course of the obturator nerve is often consistent, variations in pelvic vascular and nervous structures do exist, and clinicians should be aware of the possibility of encountering less common presentations of the obturator nerve. Knowledge of alternative course of obturator nerve has a significant impact during pelvic surgery, addressing pelvic fractures resulting from trauma or osteoporosis and approaches to regional anesthesia. This is the first report on the uncommon course of obturator nerve through an independent osseus tunnel in the pelvic bone. Its clinical relevance in surgery or trauma related to pelvic bone will be discussed.