Anatomical variations of the lumbar plexus: a descriptive anatomy study with proposed clinical implications

Abstract

This study used dissection of 34 lumbar plexes to look at the prevalence of anatomical variations in the lumbar plexus and the six peripheral branches from the origin at the ventral roots of (T12) L1-L4 to the exit from the pelvic cavity. Prevalence of anatomical variation in the individual nerves ranged from 8.8-47.1% with a mean prevalence of 20.1%. Anatomical variations included absence of the iliohypogastric nerve, an early split of the genitofemoral nerve into genital and femoral branches, an aberrant segmental origin for the lateral femoral cutaneous nerve, bifurcation of the lateral femoral nerve prior to exiting the pelvic cavity, bifurcation of the femoral nerve into two to three slips separated by psoas major muscle fibers, the presence of a single anterior femoral cutaneous nerve rather than the normal presentation of two separate anterior femoral cutaneous branches, and the presence of an accessory obturator nerve. Comparison with relevant research literature showed a wide variation in reported prevalence of the anatomical variations noted in this study. Clinical implications and directions for future research are proposed.

Keywords: Anatomical Variation; Clinical Implications; Lumbar Plexus.

Figures

FIGURE 1

Lumbar plexus with surrounding musculature: Normal anatomy

FIGURE 2

Variation of the genitofemoral nerve. The genitofemoral nerve has prematurely bifurcated into two components, the genital branch (G) and femoral branch (F). Fibers of the psoas major lie between these branches.

FIGURE 3

Variation of the femoral nerve. Cadaver 8 Left. The psoas major is sectioned (PMS) to reveal the bifurcation of the femoral nerve into medial and lateral segments (FM & FL) with an interconnecting segment (FIS). There are fibers of the psoas major (PM) traversing between this nerve plexus.

FIGURE 4

Variation of the femoral nerve. Cadaver #10 Right. The femoral nerve (F) bifurcates into a medial (FM) and lateral (FL) segment. The lateral segment travels posterior to the PM proper (PM), exits along the lateral border, and then rejoins the medial segment.