The fifth sacral dorsal rami, which are smaller than the dorsal rami above, exit the sacral canal through the sacral hiatus between the fifth sacral and first coccygeal vertebrae, below multifidus.  They join with the dorsal rami of S4 and the Co1 to form loops on the dorsum of the sacrum, from which branches arise to supply skin over the coccyx.

Supply
Skin over the coccyx.