Spinal Level Contribution to Nerves of the Lumbar Plexus- A Systemic Review

Abstract The lumbar plexus originates from the lumbar spinal cord providing sensation to the anterolateral abdominal wall and lower limbs. Primary motor components of the plexus include the femoral and obturator nerves, which innervate the anterior and medial compartments of the thigh, respectively. The plexus typically consists of four ventral segments (L1-L4) (73%); however, it can also consist of five segments (L1-L5) (21%), or even six segments (T12-L5) (6%). The furcal nerve of L4 typically ramifies to both the lumbar and sacral plexuses. An increase in laparoscopic surgeries, especially retroperitoneal approaches, made the areas around the psoas major muscle of major concern. Surgeons operating around the area should be aware of the natural variations in the lumbar plexus to avoid injuries. In this systematic review, we reviewed up to 1248 lumbar plexus variations in the literature. A comprehensive search was carried out using PRISMA guidelines to access the literature published about spinal levels. The femoral nerve was found to originate from L2-L4 in 83% of the cases. The obturator nerve was found to originate from L2-L4 in 83% of the cases. The accessory obturator nerve was found 14% of the time. The ilioinguinal nerve was found to originate from L1 in 81% of the cases. The iliohypogastric nerve was found to originate from L1 in 83% of the cases. The lateral femoral cutaneous nerve was found to originate from L2 and L3 in 72% of the cases. Finally, the genitofemoral nerve was found to originate from L1 and L2 in 81% of the cases. Mini-abstract Knowledge about the natural variations of nerves of the lumbar plexus is of major importance for operating surgeons in the abdomen or pelvis to avoid injuries to the nerves.