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Background: Anatomical ethnic variations of the obturator nerve have been
described in other populations. Chronic groin pain especially in athletes due to
obturator nerve neuropathy has been reported in local population. Iatrogenic injury to
the nerve has also been documented especially in acetabular reconstruction. Good
anatomical understanding and relevance in surgical approaches and intervention in
situations such as pelvic fractures, acetabular labral cysts, obturator nerve ganglions
among others are important.
Objective: To determine the variations in the course of obturator nerve main trunk,
level of division into anterior and posterior branches and distribution of branches in
the adult Kenyan population.
Methods: Anatomical descriptive cross-sectional study done at Human Anatomy
Laboratory, Moi University, involved census of sixty adult black Kenyan specimens
which were dissected from obturator nerve main trunk, divisions, and distribution of
anterior and posterior branches. Location of the nerve in obturator foramen was
measured in relation to most medial, inferior and superolateral points. Photography
done and data recorded in a structured data collection sheet. Analysis for variables
was done using STATA version 13 SE and presented in prose and diagrams.
Comparison of the measurements between the sexes and left and right side were done
using two sample t-tests.
Results: Main trunk emerged from the medial border of the psoas major muscle,
descended on the lateral wall of the lesser pelvis towards the obturator foramen.
Intatrapelvic branch to the obturator externus occurred in 3.33% of specimens.The
nerve exited obturaor canal at mean distance of 14.95mm from the most medial point
of obturator foramen. Majority divided into anterior and posterior branches in the
obturator canal at 88.3% and in the thigh at 11.7%. Anterior division branches
innervated all of adductor longus, gracilis, 98.3% of adductor brevis and 6.7% of
pectineus in all specimens recorded. Supply to adductor longus and gracilis were from
the same division in 70% with the rest arising independently from the anterior
division branches. The posterior division branches supplied adductor magnus in all
specimens, 1.7% of adductor brevis specimens and all of obturator externus. Articular
branch in the specimens came from anterior division branches in 60%, 30% from
common trunk and 10% from posterior division branches. No statistical difference
between the sexes and the sides were noted as shown by the p-values.
Conclusion: Intrapelvic branch to obturator externus is present in local population.
The division into anterior and posterior in majority occurred within the obturator
canal. Anterior division branches supplied adductor longus, gracilis, most of adductor
brevis and occasionally pectineus. Posterior division branches supplied adductor
magnus, obturator externus and rarely adductor brevis.
Recommendations: Surgeons should be aware of variations in obturator nerve main
trunk, divisions, and branches during surgery. The most medial and most inferior
points of the obturator foramen allow for safe transforaminal procedures. |
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