The first and second, and sometimes the third and fourth lumbar nerves are each connected with the lumbar part of the sympathetic trunk by a white ramus communicans.
12.
Sciatica is generally caused by the compression of lumbar nerves L4, or L5 or sacral nerves S1, S2, or S3, or by compression of the sciatic nerve itself.
13.
"' Posterior divisions "': The medial branches of the posterior divisions of the lumbar nerves run close to the articular processes of the vertebrae and end in the multifidus muscle.
14.
The involvement of spinal reflexes in the genesis of muscular spasticity suggested its possible treatment by surgical interruption of the sensory branch of the thoracic and lumbar nerves ( rhizotomy ), and Foerster developed in 1908 an operation to cut the posterior sensory root in order to alleviate spasticity.
