Posterior Ramus of Fourth Sacral Nerve (Left)
Ramus posterior nervi sacralis quarti
Read moreQuick Facts
Origin: Fourth sacral nerve (S4).
Course: Emerges from the posterior sacral foramen, caudal to the multifidus muscle.
Branches: Forms neuronal loops on dorsum of the sacrum with the posterior rami of S5 and Co.
Supply: Sensory innervation to the skin over the coccyx.
Origin
The posterior ramus of fourth sacral nerve originates as one of two terminal branches of the fourth sacral nerve, the other being the anterior ramus.
Course
The posterior ramus of fourth sacral nerve is smaller compared to the preceding upper sacral rami. It emerges from the posterior sacral foramen and lies caudal to the multifidus muscle.
Branches
The posterior ramus of fourth sacral nerve unites with the posterior rami of the fifth sacral and the coccygeal nerves to form neuronal loops posterior to the sacrum.
Supplied Structures & Function
Filaments from the loops provide sensory innervation to the skin over the coccyx.
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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).
