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Posterior Root of First Lumbar Nerve (Right)
Nervous System

Posterior Root of First Lumbar Nerve (Right)

Radix posterior nervi lumbalis primi

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Quick Facts

Origin: In or just lateral to the intervertebral foramen below the first lumbar vertebra (L1).

Course: Medially through the intervertebral foramen and superiorly 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 skin of the lower back, inguinal, and pubic region. Autonomic innervation to the hindgut and genitals.

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Origin

The posterior root of the first lumbar nerve originates in, or just lateral, to the intervertebral foramen, inferior to the first lumbar (L1) vertebra. It is at this point that the first lumbar nerve splits into anterior and posterior roots.

Course

The posterior root of the first lumbar nerve runs medially through the intervertebral foramen. Inside the vertebral canal, it runs superiorly towards its corresponding spinal cord level. The posterior root runs posterior to the denticulate ligament and splits into smaller rootlets, before entering the dorsal aspect of the spinal cord.

Branches

The posterior root of the first lumbar nerve branches into several smaller rootlets before entering the dorsal aspect of the spinal cord.

Supplied Structures

The posterior root of the first lumbar nerve carries sensory information from the skin of the lower back and inguinal region. It also carries autonomic afferent fibers to the hindgut, kidneys, and genitals.

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Lumbar Nerves

ScienceDirect image

The ileoinguinal nerve arises from the first lumbar nerve, giving branches to the obliquus internus muscle and to the skin covering the mons pubis and labia majora.

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