The nerves then split into an anterior branch, which travels forward, and a posterior branch, which travels backwards and supplies the area of the back.

The middle divisions of the posterior branches run close to the articular processes of the vertebrae and end in the multifidus muscle.

The outer branches supply the erector spinae muscles.

The anterior divisions communicate with the sympathetic trunk.

Near the origin of the divisions, they are joined by gray rami communicantes from the lumbar ganglia of the sympathetic trunk.

These rami consist of long, slender branches which accompany the lumbar arteries around the sides of the vertebral bodies, beneath the Psoas major.

Their arrangement is somewhat irregular: one ganglion may give rami to two lumbar nerves, or one lumbar nerve may receive rami (branches) from two ganglia.

The nerves pass obliquely outward behind the Psoas major, or between its fasciculi, distributing filaments to it and the Quadratus lumborum.

As the nerves travel forward, they create nervous plexuses.

The smaller part of the fourth joins with the fifth to form the lumbosacral trunk, which assists in the formation of the sacral plexus.

"Alternative Approach for Lumbar Transforaminal Epidural Steroid Injections."