Coccygeal plexus and anococcygeal nerve

The coccygeal plexus is a network of nerves that lies in the lower sacral and coccygeal regions. It is formed by the ventral rami of the fourth and fifth sacral nerves (S4 - S5) and the coccygeal nerve (Co). The fourth sacral nerve (S4) gives only a small contribution via a small descending branch, while the fifth sacral nerve (S5) provides a major contribution. Additionally, the plexus also receives a contribution from the sacral sympathetic trunk via the gray rami communicantes.