Which lumbar segments correspond with the lumbar plexus?

• A. L1-L4
• B. C5-T1
• C. L4-S4
• D. C1-C4

Answer: (A)

The lumbar plexus is formed primarily by the ventral primary rami of the lumbar spinal nerves, specifically L1 to L4. This network of nerves innervates the muscles and skin of the lower abdominal wall, hips, and anterior and medial aspects of the thigh. Each of these lumbar segments contributes specific nerves to the plexus, including major nerves like the femoral nerve and the obturator nerve.

The other choices do not correspond to the correct segments for the lumbar plexus. The cervical segments (C5-T1 and C1-C4) are related to the cervical plexus and brachial plexus, which innervate the upper extremities and parts of the neck, rather than the lumbar region. The segment L4-S4 pertains to the sacral plexus, which is involved with the innervation of the lower limbs but is not considered part of the lumbar plexus. Therefore, the choice highlighting L1 to L4 succinctly encapsulates the origins of the lumbar plexus.