The<unk>  is a nervous plexus in the<unk>  region of the body. It is formed by the loops of communication between the anterior divisions of the first three and the greater part of the fourth<unk>  nerves; the first<unk>  often receives a branch from the last thoracic nerve.
It is situated in the posterior part of the Psoas major, in front of the transverse processes of the<unk>  vertebræ.
The mode in which the plexus is arranged varies in different subjects.
Lumbar plexus
Cervical plexus
Sacral plexus
Lumbar nerves
Brachial plexus
Plexus
Trigeminocerebellar fibers
Ventral ramus of spinal nerve