Description
The posterior rami of the sacral nerves are the posterior branches of the first to fifth sacral (S1—S5) nerves. They are one of two branches of the sacral nerves; the other is the anterior rami.
After branching out from their respective sacral nerves, the posterior rami divide into medial and lateral branches. Medial branches of the first to third posterior rami of sacral nerves (S1-S3) innervate the multifidus muscle in the back. The lateral branches of provide sensory cutaneous innervation to the posterior gluteal skin. The lower posterior sacral rami of the fourth and fifth sacral nerve combine with posterior coccygeal ramus to innervate the skin over the coccyx and the perianal region.
Note: the coccygeal posterior spinal ramus does not divide into medial and lateral branches.
