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 the ...

emerging from the

lumbar vertebrae The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse p ...

. 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 The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

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 multifidus (multifidus spinae : ''pl. multifidi'' ) muscle consists of a number of fleshy and tendinous fasciculi, which fill up the groove on either side of the spinous processes of the vertebrae, from the sacrum to the axis. While very th ...

. 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 The greater trochanter of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system. It is directed lateral and medially and slightly posterior. In the adult it is about 2–4 cm lower than the femoral head.Stan ...

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 The sympathetic trunks (sympathetic chain, gangliated cord) are a paired bundle of nerve fibers that run from the base of the skull to the coccyx. They are a major component of the sympathetic nervous system. Structure The sympathetic trunk lies j ...

. 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 lumbar plexus is a web of nerves (a nervous plexus) in the lumbar region of the body which forms part of the larger lumbosacral plexus. It is formed by the Ventral ramus of spinal nerve, divisions of the first four lumbar nerves (L1-L4) and ...

. 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 The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse p ...

(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 The iliopsoas muscle (; from lat, ile, lit=groin and grc, ψόᾱ, psóā, muscles of the loins) refers to the joined psoas major and the iliacus muscles. The two muscles are separate in the abdomen, but usually merge in the thigh. They are usua ...

(partly)

Second lumbar nerve

The second lumbar spinal nerve (L2) originates from the spinal column from below the

lumbar vertebra 2 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 ...

(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 The iliopsoas muscle (; from lat, ile, lit=groin and grc, ψόᾱ, psóā, muscles of the loins) refers to the joined psoas major and the iliacus muscles. The two muscles are separate in the abdomen, but usually merge in the thigh. They are usu ...

(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) *

obturator externus The external obturator muscle, 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 sometimes c ...

(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 The gluteus medius, one of the three gluteal muscles, is a broad, thick, radiating muscle. It is situated on the outer surface of the pelvis. Its posterior third is covered by the gluteus maximus, its anterior two-thirds by the gluteal aponeuros ...

gluteus minimus muscle The gluteus minimus, or glutæus minimus, the smallest of the three gluteal muscles, is situated immediately beneath the gluteus medius. Structure It is fan-shaped, arising from the outer surface of the ilium, between the anterior and infe ...

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 ...

* inferior gemellus *

quadratus femoris The quadratus femoris is a flat, quadrilateral skeletal muscle. Located on the posterior side of the hip joint, it is a strong external rotator and adductor of the thigh, but also acts to stabilize the femoral head in the acetabulum. Quadratu ...

tibialis anterior The tibialis anterior muscle is a muscle in humans that originates along the upper two-thirds of the lateral (outside) surface of the tibia and inserts into the medial cuneiform and first metatarsal bones of the foot. It acts to dorsiflex and inve ...

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 The gluteal muscles, often called glutes are a group of three muscles which make up the gluteal region commonly known as the buttocks: the gluteus maximus, gluteus medius and gluteus minimus. The three muscles originate from the ilium and sacr ...

mainly S1 *

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 The extensor digitorum brevis muscle (sometimes EDB) is a muscle on the upper surface of the foot that helps extend digits 2 through 4. Structure The muscle originates from the forepart of the upper and lateral surface of the calcaneus (in fron ...

extensor hallucis longus The extensor hallucis longus muscle is a thin skeletal muscle, situated between the tibialis anterior and the extensor digitorum longus. It extends the big toe and dorsiflects the foot. It also assists with foot eversion and inversion. Struct ...

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

Structure

Posterior divisions

Anterior divisions

Divisions

First lumbar nerve

Second lumbar nerve

Third lumbar nerve

Fourth lumbar nerve

Fifth lumbar nerve

Function

Additional images

See also

References