The lumbar and sacral plexuses

The lumbar plexus is derived from the anterior primary rami of L1, L2, L3, and part of L4. It may also receive a contribution from T12. Its major derivatives are the femoral and the obturator nerves. The sacral plexus arises from the anterior primary rami of the five sacral nerves and the coccygeal nerve, together with the lumbosacral trunk, an important contribution which comprises the whole of L5 together with a contribution from L4. Its terminal branches are the sciatic and the pudendal nerve. In addition, both plexuses have numerous collateral muscular and cutaneous branches, and the sacral plexus gives rise to the pelvic parasympathetic outflow from S2 and S3.