Ventral ramus of spinal nerve

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Ventral ramus of spinal nerve

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(Redirected from Ventral 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 [edit on Wikidata]

The ventral ramus (pl.: rami) (Latin for 'branch') is the anterior division of a spinal nerve. The ventral rami supply the antero-lateral parts of the trunk and the limbs. They are mainly larger than the dorsal rami.

Shortly after a spinal nerve exits the intervertebral foramen, it branches into the dorsal ramus, the ventral ramus, and the ramus communicans. Each of these three structures carries both sensory and motor information. Each spinal nerve is a mixed nerve that carries both sensory and motor information, via efferent and afferent nerve fibers—ultimately via the motor cortex in the frontal lobe and to somatosensory cortex in the parietal lobe—but also through the phenomenon of reflex.

In the thoracic region they remain distinct from each other and each innervates a narrow strip of muscle and skin along the sides, chest, ribs, and abdominal wall. These rami are called the intercostal nerves. In regions other than the thoracic, ventral rami converge with each other to form networks of nerves called nerve 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: the cervical plexus contains 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. The brachial plexus contains ventral rami from spinal nerves C5–T1. This plexus innervates the pectoral girdle and upper limb. The lumbar plexus contains ventral rami from spinal nerves L1–L4. The sacral plexus contains 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 the lumbosacral plexus.

References

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This article incorporates text in the public domain from page 925 of the 20th edition of Gray's Anatomy (1918)

External links

[edit]

terminologyanatplanes at The Anatomy Lesson by Wesley Norman (Georgetown University) (typicalspinalnerve)
Atlas image: abdo_wall72 at the University of Michigan Health System - "Lumbosacral plexus"

Nervous tissue

CNS

Tissue Types

Cell Types

Neuronal	Pyramidal Purkinje Granule Von Economo Medium spiny Interneuron
Glial	Astrocyte Ependymal cells Tanycyte Oligodendrocyte progenitor cell Oligodendrocyte Microglia

PNS

General	Dorsal Root Ganglion Ramus Ventral Root Ramus Ramus communicans Gray White Autonomic ganglion (Preganglionic nerve fibers Postganglionic nerve fibers) Nerve fascicle Funiculus
Connective tissues	Epineurium Perineurium Endoneurium
Neuroglia	Myelination: Schwann cell Neurilemma Myelin incisure Node of Ranvier Internodal segment Satellite glial cell

Neurons/
nerve fibers

Parts

Soma	Axon hillock
Axon	Telodendron Axon terminals Axoplasm Axolemma Neurofibril/neurofilament
Dendrite	Nissl body Dendritic spine Apical dendrite/Basal dendrite

Types

Afferent nerve fiber/
Sensory neuron

Efferent nerve fiber/
Motor neuron

Termination

Synapse	Electrical synapse/Gap junction Chemical synapse Synaptic vesicle Active zone Postsynaptic density Autapse Ribbon synapse Neuromuscular junction
Sensory receptors	Meissner's corpuscle Merkel nerve ending Pacinian corpuscle Ruffini ending Muscle spindle Free nerve ending Nociceptor Olfactory receptor neuron Photoreceptor cell Hair cell Taste receptor

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