The lumbar plexus is a neuroanatomical structure comprising five primary nerves originating from spinal roots L1 through L4 (and contributing fibers to the lumbosacral trunk), which emerge exclusively from the posterior surface of the psoas major muscle. This theoretical framework defines specific sensory and motor distributions for each branch, including innervation of abdominal musculature, cutaneous supply to the anterior thigh and genitalia, and compartment-specific motor control within the leg via divisions that pass under or through fascial boundaries like the inguinal ligament. The concept establishes a topological relationship between these nerves and adjacent retroperitoneal structures such as the kidney, defining critical safety corridors where injury results in defined deficits including muscle weakness, sensory loss, or post-operative hernias.
The lumbar plexus is a neuroanatomical structure comprising five primary nerves originating from spinal roots L1 through L4 (and contributing fibers to the lumbosacral trunk), which emerge exclusivel…