What defines the course of the genitofemoral nerve?

The genitofemoral nerve, which primarily arises from the L1 and L2 spinal nerves, is indeed notable for its bifurcation into two distinct branches: the genital branch and the femoral branch. The genital branch primarily supplies the cremaster muscle in males and contributes sensory innervation to the skin of the scrotum or labia majora. The femoral branch provides sensory supply to the upper anterior thigh. This division into two branches is a key characteristic that differentiates the genitofemoral nerve from other nerves in the lumbar plexus.

Regarding the other options, while the genitofemoral nerve does arise from spinal roots L1 and L2, it does not arise from L2 and L3 as stated in one of the choices. It also does not pass under the inguinal ligament; instead, it typically emerges through the psoas major muscle and then travels downwards in front of it, before separating into its branches. Lastly, the genitofemoral nerve does not supply the quadriceps muscle; the innervation to the quadriceps comes from the femoral nerve, which originates from different roots (L2, L3, and L4). Thus, the defining bifurcation