From which plexus does the sciatic nerve arise?

From which plexus does the sciatic nerve arise?

• A. Lumbar plexus
• B. Sacral plexus
• C. Coccygeal plexus
• D. Brachial plexus

Answer: (B)

The sciatic nerve comes from the sacral plexus. The sacral plexus is formed by ventral rami of L4 to S4 in the pelvis, and the sciatic nerve is its largest branch, typically carrying fibers from L4–S3. It exits the pelvis via the greater sciatic foramen, usually below the piriformis, travels down the posterior thigh, and then splits into the tibial and common fibular nerves near the knee. The other plexuses—lumbar (anterior thigh and abdominal walls), coccygeal (around the tailbone), and brachial (upper limb)—do not give rise to the sciatic nerve.

The sciatic nerve comes from the sacral plexus. The sacral plexus is formed by ventral rami of L4 to S4 in the pelvis, and the sciatic nerve is its largest branch, typically carrying fibers from L4–S3. It exits the pelvis via the greater sciatic foramen, usually below the piriformis, travels down the posterior thigh, and then splits into the tibial and common fibular nerves near the knee. The other plexuses—lumbar (anterior thigh and abdominal walls), coccygeal (around the tailbone), and brachial (upper limb)—do not give rise to the sciatic nerve.