ANATOMICAL VARIATIONS AND DISTRIBUTIONS OF OBTURATOR NERVE ON ETHIOPIAN CADAVERS

Abstract

ABSTRACT Introduction: Obturator nerve arises from the ventral divisions of the second, third, and fourth lumbar nerves. However, the nerve has also been reported to arise only from the third and fourth lumbar nerves. The nerve divides into anterior, posterior and hip articular branches at variable levels in the inguinal region around the obturator canal. The anterior and posterior branches provide variable subdivisions to provide innervation for medial compartment muscles of thigh. Accessory obturator nerve forms part of the lumbar plexus and is occasionally present in 10% of the population. Objective: The study has been conducted to assess the anatomical variations and distribution of obturator nerve on Ethiopian cadavers. Method: Observational based descriptive study design was implemented to assess the anatomical variations and distribution of obturator nerve on 34 (67sides) embalmed human specimens in dissection rooms of Anatomy Departments of the selected seven Ethiopian public universities from October 2017 to February 2018. Anatomy of obturator nerve was examined bilaterally from origin to its final distribution and the variations and normal features were recorded and photographed. Result: A total of 34 cadavers (67 sides; 34 right and 33 left sides) were observed in this study. Obturator nerve arise from L2, L3 and L4 spinal nerves in 88.1%and from L3 and L4 spinal nerves in 11.9% of the specimens. In 23.9%, 44.8% and 31.3% of specimens the bifurcation levels of obturator nerve was determined to be intrapelvic, within the obturator canal and extrapelvic, respectively. The anterior branch subdivided into two, three and four subdivisions in 9%, 65.7% and 25.4% of the specimens, respectively. Posterior branch provides two subdivisions in 65.7% and three subdivisions in 34.3% of the specimens. Hip articular branch most commonly arises from common obturator nerve in 67.2% to provide sensory innervation to the hip joint. AON was not observed at all in this study. Conclusion: The study shows that there are important variations with regard to the prevalence of variations of the root values, the bifurcation levels into its branches around the obturator canal and the subdivisions of the anterior and posterior branches of the obturator nerve. Knowledge of these variations is important for pelvic and hip joint surgeries; and for proper localization and blocking of the nerve along with evaluation of groin pain.