Posterior Root of Fourth Sacral Nerve (Right)
Radix posterior nervi sacralis quarti
Read moreQuick Facts
Origin: In or just medial to the fourth sacral foramen.
Course: Medially from the sacral foramen and superiorly within the vertebral canal towards the posterior surface of the appropriate spinal cord level.
Branches: Unnamed rootlets just prior to entering the spinal cord.
Supply: Sensory innervation from the perianal region.
Origin
The posterior root of the fourth sacral nerve originates in, or just medial, to the fourth sacral foramen. It is at this point that the fourth sacral nerve splits into anterior and posterior roots.
Course
The posterior root of the fourth sacral nerve runs medially from the fourth sacral foramen into the vertebral canal. Here, it runs superiorly towards its corresponding spinal cord level, in a large bundle of nerve roots called the cauda equina. The posterior root splits into smaller rootlets before entering the dorsal aspect of the spinal cord.
Branches
The posterior root of the fourth sacral nerve branches into several smaller rootlets shortly before entering the dorsal aspect of the spinal cord.
Supplied Structures
The posterior root of the fourth sacral nerve carries sensory innervation from the perianal region surrounding the anus.
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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).
