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Posterior Ramus of Fourth Sacral Nerve (Left)
Nervous System

Posterior Ramus of Fourth Sacral Nerve (Left)

Ramus posterior nervi sacralis quarti

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Quick 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.

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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.

Learn more about this topic from other Elsevier products

Sacral Nerves

ScienceDirect image

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).

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