Surgical anatomy of the femoral nerve in formalin prefixed cadavers in an adult Kenya population

Abstract

Background: Ethnic variations involving femoral nerve have been described in literature. This nerve is the largest branch of the lumbar plexus. It innervates the hip flexors, knee extensors, and sensory function to medial and anterior aspects of the thigh. Risks of insults to nerve can be non-iatrogenic (trauma), and iatrogenic (approaches to the acetabulum, pelvis and proximal femur). The study aimed at providing precise description of variant anatomy of nerve, hence will help surgeons avoid iatrogenic insults. Methods: An anatomic descriptive cross-sectional study design involving fifty six (56), formalin prefixed adult cadaveric specimens. The length of the femoral nerve in relation to the inguinal ligament and its bony attachments, and the patterns of distribution of main branches in the regions were defined. Results: Males-35 (Left=17, Right=18); Females-21(Left=7, Right=14). Femoral nerve location: 53.02 mm (SD 14.59) from the ipsilateral anterior superior iliac spine (ASIS). Nerve trunk in relation to inguinal ligament measured: 47.85mm (SD 13.719) from the psoas muscle proximally and branched 29.32 mm (SD 14.239) distally. Innervations and branches: quadriceps in all specimens (Posterior); Sartorius muscles (Anterior), with noted variability in individual muscles. Branching pattern variations: 6 limbs (10.71%) at ligament level, 2(3.57%) limbs more proximal, while one nerve was split by a slip from the psoas muscle and then united 25.88mm proximal to ligament. The variations in sex were not statistically significant (p> 0.05). Conclusion:The anatomical course, length and branches of the femoral nerve in relation to inguinal ligament concur to great extent with described anatomic studies with some noted variability. Surgeons should be aware of the anatomic variations of femoral nerve and be cautious when operating in the zones traversed by the nerve.