Which nerve is occasionally present as an additional contributor to the lumbar plexus?

Which nerve is occasionally present as an additional contributor to the lumbar plexus?

• A. Accessory obturator
• B. Iliohypogastric
• C. Ilioinguinal
• D. Genitofemoral

Answer: (A)

Anatomical variation in the lumbar plexus can include an extra nerve that sometimes adds to the network. The accessory obturator nerve arises from the ventral divisions of L2–L4 (occasionally L3–L4) and, in some individuals, travels to join the obturator nerve. This provides additional fibers to the medial thigh muscles (notably the pectineus) and can contribute to hip joint innervation. Because this nerve isn’t always present, it’s considered an occasional contributor to the lumbar plexus. The other nerves listed are standard branches of the plexus rather than occasional extras, so they don’t describe this variant.

Anatomical variation in the lumbar plexus can include an extra nerve that sometimes adds to the network. The accessory obturator nerve arises from the ventral divisions of L2–L4 (occasionally L3–L4) and, in some individuals, travels to join the obturator nerve. This provides additional fibers to the medial thigh muscles (notably the pectineus) and can contribute to hip joint innervation. Because this nerve isn’t always present, it’s considered an occasional contributor to the lumbar plexus. The other nerves listed are standard branches of the plexus rather than occasional extras, so they don’t describe this variant.