Theventral ramus(pl.:rami) (Latin for 'branch') is the anterior division of aspinal nerve.The ventral rami supply the antero-lateral parts of thetrunkand the limbs. They are mainly larger than thedorsal rami.
| Ventral ramus | |
|---|---|
 The formation of the spinal nerve from the dorsal and ventral roots. (Ventral ramus labeled at lower left.) | |
| Details | |
| Identifiers | |
| Latin | ramus anterior nervi spinalis |
| TA98 | A14.2.00.034 |
| TA2 | 6147 |
| FMA | 5982 |
| Anatomical terms of neuroanatomy | |
Shortly after a spinal nerve exits theintervertebral foramen,it branches into thedorsal ramus,the ventral ramus, and theramus communicans.Each of these three structures carries bothsensoryandmotorinformation. Eachspinal nerveis amixed nervethat carries both sensory and motor information, viaefferentandafferent nerve fibers—ultimately via the motor cortex in the frontal lobe and to somatosensory cortex in the parietal lobe—but also through the phenomenon ofreflex.
In the thoracic region they remain distinct from each other and eachinnervatesa narrow strip of muscle and skin along the sides, chest, ribs, and abdominal wall. These rami are called theintercostal nerves.In regions other than the thoracic, ventral rami converge with each other to form networks of nerves callednerve plexuses.Within each plexus, fibers from the various ventral rami branch and become redistributed so that each nerve exiting the plexus has fibers from several different spinal nerves. One advantage to having plexes is that damage to a single spinal nerve will not completely paralyze a limb.
There are four main plexuses formed by the ventral rami: thecervical plexuscontains ventral rami from spinal nerves C1–C4. Branches of the cervical plexus, which include the phrenic nerve, innervate muscles of the neck, the diaphragm, and the skin of the neck and upper chest. Thebrachial plexuscontains ventral rami from spinal nerves C5–T1. This plexus innervates the pectoral girdle and upper limb. Thelumbar plexuscontains ventral rami from spinal nerves L1–L4. Thesacral plexuscontains ventral rami from spinal nerves L4–S4. The lumbar and sacral plexuses innervate the pelvic girdle and lower limbs.
Ventral rami, including the sinuvertebral nerve branches, also supply structures anterior to the facet joint, including the vertebral bodies, the discs and their ligaments, and joins other spinal nerves to form thelumbosacral plexus.
References
edit
This article incorporates text in thepublic domainfrompage 925of the 20th edition ofGray's Anatomy(1918)
External links
edit- terminologyanatplanesat The Anatomy Lesson by Wesley Norman (Georgetown University) (typicalspinalnerve)
- Atlas image: abdo_wall72at the University of Michigan Health System - "Lumbosacral plexus"
