Plexus

The four primary nerve plexi are the cervical plexus, brachial plexus, lumbar plexus, and the sacral plexus.

The choroid plexus is a part of central nervous system in the brain and it consist of capillaries, ventricles and ependymal cells.

In invertebrates

The plexus is the characteristic form of nervous system in the coelenterates and persists with modifications in the flatworms. The nerves of the radially symmetric echinoderms also take this form, where a plexus underlies the ectoderm of these animals and deeper in the body other nerve cells form plexi of limited extent.