Posterior Ramus of Second Sacral Nerve (Right)
Ramus posterior nervi sacralis secundi
Read moreQuick Facts
Origin: Second sacral nerve (S2).
Course: Emerges from the posterior sacral foramen, underneath the multifidus muscle.
Branches: Medial and lateral branches.
Supply: Motor innervation to the multifidus muscle and sensory innervation to the posterior gluteal skin.
Origin
The posterior ramus of second sacral nerve originates as one of two terminal branches of the second sacral nerve, the other being the anterior ramus.
Course
The posterior ramus emerges from the posterior sacral foramen and is covered at its exit by the multifidus muscle in the back. It divides into medial and lateral branches. At lower sacral levels (S2-S4), the posterior sacral rami diminish in size.
Branches
The medial branch is small and terminates in the multifidus muscle.
The lateral branch joins with branches of the fifth lumbar nerve (L5), first sacral (S1) and all other posterior sacral rami to form loops posterior to the sacrum. Branches from these loops run posterior to the sacrotuberous ligament and form a second series of loops under gluteus maximus. Two or three gluteal nerves arise here to pierce the gluteus maximus (along a line from the posterior superior iliac spine to the coccygeal apex) and provide sensory cutaneous innervation to the posterior gluteal skin.
Supplied Structures
The medial branch supplies motor innervation to the multifidus muscle. The lateral branch supplies sensory cutaneous innervation to the posterior gluteal skin (middle cluneal nerve).
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Sacral Nerves
The sacral nerves are a set of five spinal nerves that project to the pelvic floor, carrying afferent and efferent fibers for communication between pelvic organs and the central nervous system (CNS).
