The lumbar nerves are the five pairs of

spinal nerves A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into ...

emerging from the

lumbar vertebrae The lumbar vertebrae are located between the thoracic vertebrae and pelvis. They form the lower part of the back in humans, and the tail end of the back in quadrupeds. In humans, there are five lumbar vertebrae. The term is used to describe t ...

. They are divided into posterior and anterior divisions.

Structure

The lumbar nerves are five

spinal nerve A spinal nerve is a mixed nerve, which carries Motor neuron, motor, Sensory neuron, sensory, and Autonomic nervous system, autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each s ...

s which arise from either side of the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...

below the thoracic spinal cord and above the sacral spinal cord. They arise from the spinal cord between each pair of lumbar spinal vertebrae and travel through the intervertebral foramina. The nerves then split into an anterior branch, which travels forward, and a posterior branch, which travels backwards and supplies the area of the back.

Posterior divisions

The middle divisions of the posterior branches run close to the articular processes of the vertebrae and end in the multifidus muscle. The outer branches supply the

erector spinae muscles The erector spinae ( ) or spinal erectors is a set of muscles that straighten and rotate the back. The spinal erectors work together with the glutes ( gluteus maximus, gluteus medius and gluteus minimus) to maintain stable posture standing or ...

. The nerves give off branches to the skin. These pierce the

aponeurosis An aponeurosis (; : aponeuroses) is a flattened tendon by which muscle attaches to bone or fascia. Aponeuroses exhibit an ordered arrangement of collagen fibres, thus attaining high tensile strength in a particular direction while being vulnerable ...

of the greater trochanter.

Anterior divisions

The anterior divisions of the lumbar nerves () increase in size from above downward. The anterior divisions communicate with the sympathetic trunk. Near the origin of the divisions, they are joined by gray rami communicantes from the

lumbar ganglia The lumbar ganglia are paravertebral ganglia located in the inferior portion of the sympathetic trunk. The lumbar portion of the sympathetic trunk typically has 4 lumbar ganglia. The lumbar splanchnic nerves arise from the Ganglion, ganglia here, ...

of the sympathetic trunk. These rami consist of long, slender branches which accompany the lumbar arteries around the sides of the vertebral bodies, beneath the Psoas major. Their arrangement is somewhat irregular: one ganglion may give rami to two lumbar nerves, or one lumbar nerve may receive rami (branches) from two

ganglia A ganglion (: ganglia) is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system, this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system, there a ...

. The first and second, and sometimes the third and fourth lumbar nerves are each connected with the lumbar part of the sympathetic trunk by a white ramus communicans. The nerves pass obliquely outward behind the Psoas major, or between its fasciculi, distributing filaments to it and the Quadratus lumborum. As the nerves travel forward, they create nervous plexuses. The first three lumbar nerves, and the greater part of the fourth together form the

lumbar plexus The lumbar plexus is a web of nerves (a nerve plexus) in the lumbar region of the body which forms part of the larger lumbosacral plexus. It is formed by the divisions of the first four lumbar nerves (L1–L4) and from contributions of the su ...

. The smaller part of the fourth joins with the fifth to form the lumbosacral trunk, which assists in the formation of the sacral plexus. The fourth nerve is named the furcal nerve, from the fact that it is subdivided between the two plexuses.

Divisions

First lumbar nerve

The first lumbar spinal nerve (L1) originates from the spinal column from below the lumbar vertebra 1 (L1). The three terminal branches of this nerve are the iliohypogastric, ilioinguinal, and the genitofemoral nerves. L1 supplies many muscles, either directly or through nerves originating from L1. They may be innervated with L1 as single origin, or be innervated partly by L1 and partly by other spinal nerves. The muscles are: * quadratus lumborum (partly) *

iliopsoas muscle The iliopsoas muscle (; ) refers to the joined psoas major muscle, psoas major and the iliacus muscles. The two muscles are separate in the abdomen, but usually merge in the thigh. They are usually given the common name ''iliopsoas''. The iliopso ...

(partly)

Second lumbar nerve

The second lumbar spinal nerve (L2) originates from the spinal column from below the lumbar vertebra 2 (L2). L2 supplies many muscles, either directly or through nerves originating from L2. They may be innervated with L2 as single origin, or be innervated partly by L2 and partly by other spinal nerves. The muscles are: * quadratus lumborum (partly) * iliopsoas (partly)

Third lumbar nerve

The third lumbar spinal nerve (L3) originates from the spinal column from below the lumbar vertebra 3 (L3). L3 supplies many muscles, either directly or through nerves originating from L3. They may be innervated with L3 as single origin, or be innervated partly by L3 and partly by other spinal nerves. The muscles are: * quadratus lumborum (partly) * iliopsoas (partly) *

obturator externus The external obturator muscle or obturator externus muscle (; OE) is a flat, triangular muscle, which covers the outer surface of the anterior wall of the pelvis. It is sometimes considered part of the medial compartment of thigh, and sometime ...

(partly)

Fourth lumbar nerve

The fourth lumbar spinal nerve (L4) originates from the spinal column from below the lumbar vertebra 4 (L4). L4 supplies many muscles, either directly or through nerves originating from L4. They are not innervated with L4 as single origin, but partly by L4 and partly by other spinal nerves. The muscles are: * quadratus lumborum * gluteus medius muscle * gluteus minimus muscle * tensor fasciae latae *

* inferior gemellus * quadratus femoris * tibialis anterior * vastus lateralis

Fifth lumbar nerve

The fifth lumbar spinal nerve 5 (L5)American Medical Association
Nervous System -- Groups of Nerves originates from the spinal column from below the lumbar vertebra 5 (L5). L5 supplies many muscles, either directly or through nerves originating from L5. They are not innervated with L5 as single origin, but partly by L5 and partly by other spinal nerves. The muscles are: * gluteus maximus muscle mainly S1 * gluteus medius muscle * gluteus minimus muscle * tensor fasciae latae * tibialis anterior * tibialis posterior * extensor digitorum brevis * extensor hallucis longus File:Slide1w.JPG, Lumbar spinal nerve 3 File:Slide2w.JPG, Lumbar spinal nerve 4 File:CORECTAT.jpg, Lumbar spinal nerve 5 Sobo 1909 612.png, The spinal cord with spinal nerves Sobo 1909 715.png, The plan of the lumbosacral plexus

Function

Additional images

File:Gray823.png, The lumbar plexus and its branches. File:Slide4ARS.JPG, Lumbar spinal nerves.Deep dissection. Posterior view.

References

Hsu, Philip S., MD, Carmel Armon, MD, and Kerry Levin, MD. "Acute Lumbosacral Radiculopathy: Pathophysiology.Clinical, Features, and Diagnosis." www.uptodate.com. Uptodate, 11 Jan. 2011.Web. 26 Sept. 2012. https://www.uptodate.com/contents/acute-lumbosacral-radiculopathy-pathophysiology-clinical-features-and-diagnosis Loizidez, Alexander, MD, Siegfried Peer, MD, Michaela Plaikner, MD, Verena Spiss, MD, and HannesGruber, MD. "Ultrasound-guided Injections in the Lumbar Spine." www.medultrason.ro. Medical Ultrasonography, 20 Jan. 2011. Web. 26 Sept. 2012. http://www.medultrason.ro/assets/Magazines/Medultrason-2011-vol13-no1/10loizides.pdf Zhu, Jie, MD, and Obi Onyewu, MD. "Alternative Approach for Lumbar Transforaminal Epidural Steroid Injections." www.painphysicianjournal.com. Pain Physician, 21 Apr. 2011. Web. 26 Sept. 2012. http://www.painphysicianjournal.com/2011/july/2011;14;331-341.pdf {{Authority control Spinal nerves