Ventral posterolateral nucleus

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Ventral posterolateral nucleus
ThalamicNuclei.svg
Thalamus-schematic.svg
Thalamic nuclei
Details
Part of Ventral posterior nucleus
Identifiers
Latin nucleus ventralis posterolateralis thalami
NeuroNames 344
NeuroLex ID birnlex_737
TA A14.1.08.641
A14.1.08.656
FMA 62200
Anatomical terms of neuroanatomy

The ventral posterolateral nucleus (VPL) is a nucleus of the thalamus. Together with the ventral posteromedial nucleus (VPM), ventral posterior inferior nucleus (VPI) and ventromedial posterior nucleus (VMpo), it constitutes the ventral posterior nucleus. There is uncertainty in the location of VMpo, as determined by spinothalamic tract (STT) terminations and staining for calcium-binding proteins, and several authorities do not consider its existence as being proved. [1]

Thalamus part of diencephalon, which is in turn part of prosencephalon (forebrain)

The thalamus is a large mass of gray matter in the dorsal part of the diencephalon of the brain with several functions such as relaying of sensory signals, including motor signals to the cerebral cortex, and the regulation of consciousness, sleep, and alertness.

Ventral posteromedial nucleus

The ventral posteromedial nucleus (VPM) is a nucleus of the thalamus.

Ventral posterior nucleus

The ventral posterior nucleus is the somato-sensory relay nucleus in thalamus of the brain.

Contents

Input and output

The VPL receives information from the neospinothalamic tract and the medial lemniscus of the posterior column-medial lemniscus pathway. It then projects this sensory information to Brodmann's Areas 3, 1 and 2 in the postcentral gyrus. Collectively, Brodmann areas 3, 1 and 2 make up the primary somatosensory cortex of the brain.

Medial lemniscus

The medial lemniscus, also known as Reil's band or Reil's ribbon, is a large ascending bundle of heavily myelinated axons that decussate in the brainstem, specifically in the medulla oblongata. The medial lemniscus is formed by the crossings of the internal arcuate fibers. The internal arcuate fibers are composed of axons of nucleus gracilis and nucleus cuneatus. The axons of the nucleus gracilis and nucleus cuneatus in the medial lemniscus have cell bodies that lie contralaterally.

Postcentral gyrus

The postcentral gyrus is a prominent gyrus in the lateral parietal lobe of the human brain. It is the location of the primary somatosensory cortex, the main sensory receptive area for the sense of touch. Like other sensory areas, there is a map of sensory space in this location, called the sensory homunculus.

Somatosensory system Widely distributed parts of the sensory nervous system

The somatosensory system is a part of the sensory nervous system. The somatosensory system is a complex system of sensory neurons and pathways that responds to changes at the surface or inside the body. The axons of sensory neurons connect with, or respond to, various receptor cells. These sensory receptor cells are activated by different stimuli such as heat and nociception, giving a functional name to the responding sensory neuron, such as a thermoreceptor which carries information about temperature changes. Other types include mechanoreceptors, chemoreceptors, and nociceptors which send signals along a sensory nerve to the spinal cord where they may be processed by other sensory neurons and then relayed to the brain for further processing. Sensory receptors are found all over the body including the skin, epithelial tissues, muscles, bones and joints, internal organs, and the cardiovascular system.

Additional images

Related Research Articles

Medulla oblongata structure of the brain stem

The medulla oblongata is a long stem-like structure located in the brainstem. It is anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involuntary) functions ranging from vomiting to sneezing. The medulla contains the cardiac, respiratory, vomiting and vasomotor centers and therefore deals with the autonomic functions of breathing, heart rate and blood pressure.

Trigeminal nerve nerve in human face

The trigeminal nerve (the fifth cranial nerve, or simply CN V) is a nerve responsible for sensation in the face and motor functions such as biting and chewing; it is the largest of the cranial nerves. Its name ("trigeminal" = tri-, or three, and - geminus, or twin: thrice-twinned) derives from the fact that each of the two nerves (one on each side of the pons) has three major branches: the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3). The ophthalmic and maxillary nerves are purely sensory, whereas the mandibular nerve supplies motor as well as sensory (or "cutaneous") functions.

Internal capsule

The internal capsule is a white matter structure situated in the inferomedial part of each cerebral hemisphere of the brain. It carries information past the basal ganglia, separating the caudate nucleus and the thalamus from the putamen and the globus pallidus. The internal capsule contains both ascending and descending axons, going to and coming from the cerebral cortex. It also separates the caudate nucleus and the putamen in the dorsal striatum, a brain region involved in motor and reward pathways.

Spinothalamic tract

The spinothalamic tract is a sensory pathway from the skin to the thalamus. From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory cortex of the postcentral gyrus.

Dorsal column–medial lemniscus pathway

The dorsal column–medial lemniscus pathway (DCML) is a sensory pathway of the central nervous system that conveys sensations of fine touch, vibration, two-point discrimination, and proprioception (position) from the skin and joints. It transmits information from the body to the primary somatosensory cortex in the postcentral gyrus of the parietal lobe of the brain. The pathway receives information from sensory receptors throughout the body, and carries this in nerve tracts in the white matter of the dorsal columns of the spinal cord, to the medulla where it is continued in the medial lemniscus, on to the thalamus and relayed from there through the internal capsule and transmitted to the somatosensory cortex. The name dorsal-column medial lemniscus comes from the two structures that carry the sensory information: the dorsal columns of the spinal cord, and the medial lemniscus in the brainstem.

Cuneate nucleus

One of the dorsal column nuclei, the cuneate nucleus is a wedge-shaped nucleus in the closed part of the medulla oblongata, in the brainstem. It contains cells that give rise to the cuneate tubercle, visible on the posterior aspect of the medulla. It lies lateral to the gracile nucleus and medial to the spinal trigeminal nucleus in the medulla.

Gracile fasciculus

The gracile fasciculus is a nerve tract in the dorsal column-medial lemniscus pathway of the spinal cord and carries information from the lower parts of the body. The gracile fasiculus is one of many ascending tracts which carry received sensory information to the brain via the spinal cord. It is also one of the dorsal columns, the other being the cuneate fasciculus.

Anterior spinothalamic tract

The ventral spinothalamic fasciculus situated in the marginal part of the anterior funiculus and intermingled more or less with the vestibulo-spinal fasciculus, is derived from cells in the posterior column or intermediate gray matter of the opposite side. Aβ fibres carry sensory information pertaining to crude touch from the skin. After entering the spinal cord the first order neurons synapse, and the second order neurons decussate via the anterior commissure. These second order neurons ascend synapsing in the VPL of the thalamus. It should also be noted incoming first order neurons can ascend or descend via the Lissauer tract.

Lateral spinothalamic tract

The lateral spinothalamic tract, which is a part of the anterolateral system, is a bundle of afferent nerve fibers ascending through the white matter of the spinal cord, carrying sensory information to the brain. It carries pain, crude touch and temperature sensory information to the thalamus. It is composed primarily of fast-conducting, sparsely myelinated A delta fibers and slow-conducting, unmyelinated C fibers. These are secondary sensory neurons which have already synapsed with the primary sensory neurons of the peripheral nervous system in the posterior horn of the spinal cord.

Dorsal column nuclei

In neuroanatomy, the dorsal column nuclei are a pair of nuclei in the dorsal columns in the brainstem. The name refers collectively to the cuneate nucleus and gracile nucleus, which are present at the junction between the spinal cord and the medulla oblongata. Both nuclei contain second-order neurons of the dorsal column-medial lemniscus pathway, which carries fine touch and proprioceptive information from the body to the brain. Each nucleus has an associated nerve tract, the gracile fasciculus and the cuneate fasciculus.

Sensory decussation

The sensory decussation or decussation of the lemniscus is a decussation or crossover of axons from the gracile nucleus and cuneate nucleus, which are responsible for fine touch, proprioception and two-point discrimination of the body. The fibres of this decussation are called the internal arcuate fibres and are found at the superior aspect of the closed medulla superior to the motor decussation. It is part of the second neuron in the posterior column–medial lemniscus pathway.

The isothalamus is a division used by some researchers in describing the thalamus.

The ventrobasal complex (VB) is a relay nucleus of the thalamus for nociceptive stimuli received from nociceptive nerves. The VB consists of the ventral posteromedial nucleus (VPM) and the ventral posterolateral nucleus (VPL). In some species the ventral posterolateral nucleus, pars caudalis is also a part of the VB. The VB gets inputs from the spinothalamic tract, medial lemniscus, and corticothalamic tract. The main output of the VB is the primary somatosensory cortex.

The anterior trigeminothalamic tract is a tract composed of second order neuronal axons. These fibers carry sensory information about discriminative and crude touch, conscious proprioception, pain, and temperature from the head, face, and oral cavity. The anterior trigeminothalamic tract connects the principal nucleus and spinal trigeminal nucleus to the ventral posteromedial (VPM) nucleus of the thalamus.

The trigeminal lemniscus, also called the trigeminothalamic tract, is a part of the brain that conveys tactile, pain, and temperature impulses from the skin of the face, the mucous membranes of the nasal and oral cavities, and the eye, as well as proprioceptive information from the facial and masticatory muscles.

The posterior trigeminothalamic tract is composed of second order neuronal axons. These fibers carry sensory information about discriminative touch and conscious proprioception in the oral cavity from the principal nucleus to the ventral posteromedial (VPM) nucleus of the thalamus.

References

  1. Willis et al The Journal of Pain 2002;3:79-94; Graziano and Jones, The Journal of Neuroscience 2004;24:248–256