Gunnera

The posterior division of the coccygeal nerve does not divide into a medial and a lateral branch, but receives a communicating branch from the last sacral; it is distributed to the skin over the back of the coccyx.^[1]

References

^ Gray, Henry; Lewis, Warren H. (Warren Harmon) (1924). Anatomy of the human body. Philadelphia and New York : Lea & Febiger. p. 931.

This article incorporates text in the public domain from page 925 of the 20th edition of Gray's Anatomy (1918)

Spinal nerves
Cervical	C1 C2 C3 C4 C5 C6 C7 C8 anterior Cervical plexus Brachial plexus posterior Posterior branches of cervical nerves Suboccipital – C1 Greater occipital – C2 Third occipital – C3
Thoracic	T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 anterior Intercostal Intercostobrachial – T2 Thoraco-abdominal nerves – T7–T11 Subcostal – T12 posterior Posterior branches of thoracic nerves
Lumbar	L1 L2 L3 L4 L5 anterior Lumbar plexus Lumbosacral trunk posterior Posterior branches of the lumbar nerves Superior cluneal L1–L3
Sacral	S1 S2 S3 S4 S5 anterior Sacral plexus posterior Posterior branches of sacral nerves Medial cluneal nerves
Coccygeal	anterior Coccygeal plexus posterior Posterior branch of coccygeal nerve