| Lumbar nerves | |
|---|---|
 Plan oflumbar plexus. | |
| Details | |
| Identifiers | |
| Latin | nervi lumbales |
| TA98 | A14.2.05.001 |
| TA2 | 6489 |
| FMA | 5861 |
| Anatomical terms of neuroanatomy | |
Thelumbar nerves are the five pairs ofspinal nerves emerging from thelumbar vertebrae. They are divided into posterior and anterior divisions.
The lumbar nerves are fivespinal nerves which arise from either side of thespinal cord below thethoracic spinal cord and above thesacral spinal cord. They arise from the spinal cord between each pair of lumbarspinal vertebrae and travel through theintervertebral foramina. The nerves then split into ananterior branch, which travels forward, and aposterior branch, which travels backwards and supplies the area of the back.
The middle divisions of the posterior branches run close to the articular processes of the vertebrae and end in themultifidus muscle. The outer branches supply theerector spinae muscles.
The nerves give off branches to the skin. These pierce theaponeurosis of thegreater trochanter.
The anterior divisions of the lumbar nerves (Latin:rami anteriores) increase in size from above downward.
The anterior divisions communicate with thesympathetic trunk. Near the origin of the divisions, they are joined bygray rami communicantes from thelumbar ganglia of the sympathetic trunk. These rami consist of long, slender branches which accompany thelumbar arteries around the sides of the vertebral bodies, beneath thePsoas major. Their arrangement is somewhat irregular: one ganglion may give rami to two lumbar nerves, or one lumbar nerve may receiverami (branches) from twoganglia. The first and second, and sometimes the third and fourth lumbar nerves are each connected with the lumbar part of the sympathetic trunk by awhite ramus communicans.
The nerves pass obliquely outward behind thePsoas major, or between itsfasciculi, distributing filaments to it and theQuadratus lumborum.
As the nerves travel forward, they createnervous plexuses. The first three lumbar nerves, and the greater part of the fourth together form thelumbar plexus. The smaller part of the fourth joins with the fifth to form thelumbosacral trunk, which assists in the formation of thesacral plexus.
The fourth nerve is named thefurcal nerve, from the fact that it is subdivided between the two plexuses.
The first lumbar spinal nerve (L1)[1] originates from the spinal column from below thelumbar vertebra 1 (L1). The three terminal branches of this nerve are theiliohypogastric,ilioinguinal, and thegenitofemoral 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:
The second lumbar spinal nerve (L2)[2] originates from the spinal column from below thelumbar 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:
The third lumbar spinal nerve (L3)[3] originates from the spinal column from below thelumbar 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:
The fourth lumbar spinal nerve (L4)[4] originates from the spinal column from below thelumbar 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:
The fifth lumbar spinal nerve 5 (L5)[5] originates from the spinal column from below thelumbar 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:
This article incorporates text in thepublic domain frompage 924 of the 20th edition ofGray's Anatomy(1918)
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