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Anterior Root of Second Sacral Nerve (Left)
Nervous System

Anterior Root of Second Sacral Nerve (Left)

Radix anterior nervi sacralis secundi

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Quick Facts

Origin: Surface of the spinal cord ventral to the ventral horn.

Course: Inferiorly towards the second sacral foramen.

Branches: Inferior gluteal, sciatic, pudendal, and pelvic splanchnic nerves

Supply: Motor innervation to gluteal maximus, muscles of the posterior thigh, leg, and foot. Muscles of the perineum and urethral sphincter. Parasympathetic innervation to the hindgut, kidneys, reproductive organs, and genitals.

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Origin

The anterior root of the second sacral nerve originates as a series of rootlets that emerge from the ventrolateral surface of the spinal cord. These quickly merge to form the anterior root.

Course

The anterior root runs inferiorly. At lumbar and sacral levels, the anterior root descends through the vertebral column until it reaches the second sacral foramen. Just before entering this foramen, the anterior and posterior roots merge to form the spinal nerve.

Branches

There are no named branches; however, fibers do contribute to the sacral plexus, specifically, the inferior gluteal, sciatic, and pudendal nerves. Parasympathetic fibers exit the spinal cord via the second, third, and fourth sacral nerves, and combine to form the pelvic splanchnic nerve.

Supplied Structures

The anterior root of the second sacral nerve supplies the multifidus muscle via the posterior ramus. It also contributes to the sacral plexus, and the following nerves and targets.

- The inferior gluteal nerve arises from the fifth lumbar nerve and the first and second sacral nerves. It innervates the gluteus maximus muscle.

- The sciatic nerve is the longest nerve in the body. It gives rise to the common fibular, tibial, and sural nerves. It arises from the fourth and fifth lumbar nerves as well as the first, second, and third sacral nerves. The sciatic nerve innervates all the muscles of the posterior thigh, anterior and posterior leg, and foot.

- The pudendal nerve arises from the second, third, and fourth sacral nerves and transmits motor and sensory innervation to the abdomen and pelvis. Motor innervation is to the muscles of the perineum (bulbospongiosus, ischiocavernousus, superficial transverse perineal, deep transverse perineal, external anal and urethral sphincter muscles).

Muscles significantly innervated by the anterior ramus of the second sacral nerve include the gastrocnemius, soleus, abductor hallucis, abductor digiti minimi pedis, and external anal sphincter muscles.

The pelvic splanchnic nerve carries parasympathetic innervation to the hindgut organs, kidneys, reproductive organs, and genitals. Parasympathetic fibers exit the spinal cord via the second, third, and fourth sacral nerves, and combine to form the pelvic splanchnic nerve.

Learn more about this topic from other Elsevier products

Sacral Nerves

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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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