Lumbar plexus comprises which nerve roots?

Lumbar plexus comprises which nerve roots?

• A. L4-S4
• B. C1-C5
• C. C5-T1
• D. L1-L4

Answer: (D)

The lumbar plexus is formed by the ventral rami of the first through fourth lumbar nerves as they emerge in the lower back, passing through the psoas major. This root set (L1–L4) explains why the nerves in this plexus—for example, the iliohypogastric and ilioinguinal nerves (L1), genitofemoral (L1–L2), lateral femoral cutaneous (L2–L3), and the femoral and obturator nerves (L2–L4)—supply the lower abdominal wall, groin, and parts of the thigh. The other options do not match this network: the cervical roots (C1–C5) form the cervical plexus, the brachial plexus comes from C5–T1, and the sacral plexus comes from L4–S4 (with L4 contributing to the lumbosacral trunk that feeds into it).

The lumbar plexus is formed by the ventral rami of the first through fourth lumbar nerves as they emerge in the lower back, passing through the psoas major. This root set (L1–L4) explains why the nerves in this plexus—for example, the iliohypogastric and ilioinguinal nerves (L1), genitofemoral (L1–L2), lateral femoral cutaneous (L2–L3), and the femoral and obturator nerves (L2–L4)—supply the lower abdominal wall, groin, and parts of the thigh. The other options do not match this network: the cervical roots (C1–C5) form the cervical plexus, the brachial plexus comes from C5–T1, and the sacral plexus comes from L4–S4 (with L4 contributing to the lumbosacral trunk that feeds into it).