The lumbar nerves are the five pairs of spinal nerves emerging from the lumbar vertebrae. 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, 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 the ...

s which arise from either side of the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...

below the

thoracic spinal cord 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 the ...

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 intervertebral foramen (also called neural foramen, and often abbreviated as IV foramen or IVF) is a foramen between two spinal vertebrae. Cervical, thoracic, and lumbar vertebrae all have intervertebral foramina. The foramina, or openi ...

. 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 of the greater trochanter.

Anterior divisions

The anterior divisions of the lumbar nerves ( la, rami anteriores) 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 Each spinal nerve receives a branch called a gray ramus communicans (plural rami communicantes) from the adjacent paravertebral ganglion of the sympathetic trunk. The gray rami communicantes contain postganglionic nerve fibers of the sympathetic n ...

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 ganglia here, and contri ...

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 The psoas major ( or ; from grc, ψόᾱ, psóā, muscles of the loins) is a long fusiform muscle located in the lateral lumbar region between the vertebral column and the brim of the lesser pelvis. It joins the iliacus muscle to form the ilio ...

. 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 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 are both sympathe ...

. 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

, or between its

fasciculi Fascicle or ''fasciculus'' may refer to: Anatomy and histology * Muscle fascicle, a bundle of skeletal muscle fibers * Nerve fascicle, a bundle of axons (nerve fibers) ** Superior longitudinal fasciculus *** Arcuate fasciculus ** Gracile fasci ...

, distributing filaments to it and the

Quadratus lumborum The quadratus lumborum muscle, informally called the ''QL'', is a paired muscle of the left and right posterior abdominal wall. It is the deepest abdominal muscle, and commonly referred to as a back muscle. Each is irregular and quadrilateral in s ...

. 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 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 The furcal nerve (forked nerve) links the lumbar plexus and the sacral plexus. It has its own dorsal and ventral branches with fibres that branch out to become part of the femoral and obturator nerves. The furcal nerve is found in the lumbosacral ...

, 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 The iliohypogastric nerve is a nerve that originates from the lumbar plexus that supplies sensation to skin over the lateral gluteal and hypogastric regions and motor to the internal oblique muscles and transverse abdominal muscles. Structure ...

ilioinguinal The ilioinguinal nerve is a branch of the first lumbar nerve (L1). It separates from the first lumbar nerve along with the larger iliohypogastric nerve. It emerges from the lateral border of the psoas major just inferior to the iliohypogastric, a ...

, 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 The quadratus lumborum muscle, informally called the ''QL'', is a paired muscle of the left and right posterior abdominal wall. It is the deepest abdominal muscle, and commonly referred to as a back muscle. Each is irregular and quadrilateral in s ...

(partly) * iliopsoas muscle (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: *

(partly) * iliopsoas (partly)

Third lumbar nerve

The third lumbar spinal nerve (L3) originates from the spinal column from below the

lumbar vertebra 3 The lumbar vertebrae are, in human anatomy, the five vertebrae between the Human rib cage, rib cage and the Human pelvis, pelvis. They are the largest segments of the Human vertebral column, vertebral column and are characterized by the absence ...

(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: *

(partly) * iliopsoas (partly) * obturator externus (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: *

* gluteus medius muscle * gluteus minimus muscle *

tensor fasciae latae The tensor fasciae latae (or tensor fasciæ latæ or, formerly, tensor vaginae femoris) is a muscle of the thigh. Together with the gluteus maximus, it acts on the iliotibial band and is continuous with the iliotibial tract, which attaches to the ...

* obturator externus * inferior gemellus * quadratus femoris * tibialis anterior

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 *

* tibialis anterior *

tibialis posterior The tibialis posterior muscle is the most central of all the leg muscles, and is located in the deep posterior compartment of the leg. It is the key stabilizing muscle of the lower leg. Structure The tibialis posterior muscle originates on the i ...

* 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