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Spinothalamic tract
 
 
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The spinothalamic tract is a sensory pathway originating in the spinal cord. It transmits information to the thalamus
Thalamus

The thalamus is a pair and symmetric part of the brain. It constitutes the main part of the diencephalon....
 about pain
Pain

Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm....
, temperature
Temperature

In physics, temperature is a physical property of a Physical system that underlies the common notions of hot and cold; something that feels hotter generally has the greater temperature....
, itch
Itch

Itch is an unpleasant sensation that evokes the desire or reflex to scratch. Itch has resisted many attempts to classify it as any one type of sensory experience....
 and crude touch. The pathway decussates at the level of the spinal cord
Spinal cord

The spinal cord is a long, thin, tubular bundle of neuron and glia that extends from the brain. The brain and spinal cord together make up the central nervous system....
, rather than in the brainstem like the posterior column-medial lemniscus pathway
Posterior column-medial lemniscus pathway

The posterior column-medial lemniscus pathway is the sense pathway responsible for transmitting touch, vibration and proprioception information from the body to the cerebral cortex....
 and corticospinal tract
Corticospinal tract

The corticospinal or pyramidal tract is a collection of axons that travel between the cerebral cortex of the brain and the spinal cord.The corticospinal tract mostly contains motor axons....
.

The cell bodies of neurons that make up the spinothalamic tract are located principally within the dorsal horn of the spinal cord. These neurons receive input from sensory fibers that innervate the skin and internal organs.

e are two main parts of the spinothalamic tract (STT):

types of sensory information transmitted via the spinothalamic tract are described as affective sensation
Affective sensation

An affective sensation is a sensation accompanied with a strong compulsion to act on it, causing reflex action such as the scratch reflex or the withdrawal reflex....
.






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Encyclopedia


The spinothalamic tract is a sensory pathway originating in the spinal cord. It transmits information to the thalamus
Thalamus

The thalamus is a pair and symmetric part of the brain. It constitutes the main part of the diencephalon....
 about pain
Pain

Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm....
, temperature
Temperature

In physics, temperature is a physical property of a Physical system that underlies the common notions of hot and cold; something that feels hotter generally has the greater temperature....
, itch
Itch

Itch is an unpleasant sensation that evokes the desire or reflex to scratch. Itch has resisted many attempts to classify it as any one type of sensory experience....
 and crude touch. The pathway decussates at the level of the spinal cord
Spinal cord

The spinal cord is a long, thin, tubular bundle of neuron and glia that extends from the brain. The brain and spinal cord together make up the central nervous system....
, rather than in the brainstem like the posterior column-medial lemniscus pathway
Posterior column-medial lemniscus pathway

The posterior column-medial lemniscus pathway is the sense pathway responsible for transmitting touch, vibration and proprioception information from the body to the cerebral cortex....
 and corticospinal tract
Corticospinal tract

The corticospinal or pyramidal tract is a collection of axons that travel between the cerebral cortex of the brain and the spinal cord.The corticospinal tract mostly contains motor axons....
.

The cell bodies of neurons that make up the spinothalamic tract are located principally within the dorsal horn of the spinal cord. These neurons receive input from sensory fibers that innervate the skin and internal organs.

Tracts

There are two main parts of the spinothalamic tract (STT):
  • The lateral spinothalamic tract
    Lateral spinothalamic tract

    The lateral spinothalamic tract is a bundle of sensory axons ascending through the white matter of the spinal cord, carrying sensory information to the brain....
     transmits pain
    Pain

    Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm....
     and temperature
    Temperature

    In physics, temperature is a physical property of a Physical system that underlies the common notions of hot and cold; something that feels hotter generally has the greater temperature....
    .
  • The anterior spinothalamic tract
    Anterior spinothalamic tract

    The ventral spinothalamic fasciculus situated in the marginal part of the 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....
     (or ventral spinothalamic tract) transmits crude touch.


Information transmitted

The types of sensory information transmitted via the spinothalamic tract are described as affective sensation
Affective sensation

An affective sensation is a sensation accompanied with a strong compulsion to act on it, causing reflex action such as the scratch reflex or the withdrawal reflex....
. This means that the sensation is accompanied by a compulsion to act. For instance, an itch is accompanied by a need to scratch, and a painful stimulus makes us want to withdraw from the pain.

Sub-systems


There are two sub-systems identified:
  • Direct (for direct conscious appreciation of pain)
  • Indirect (for affective and arousal impact of pain). Indirect projections include
    • Spino-Reticulo-Thalamo-Cortical (part of the ascending reticular arousal system, aka ARAS)
    • Spino-Mesencephalo-Limbic (for affective impact of pain).


Path of sensation


The Spinothalamic Tract, like the Dorsal Column-Medial Lemniscus Tract, use three neurons to convey sensory information from the periphery to conscious level at the cerebral cortex.

Pseudounipolar neuron
Neuron

Neurons are responsive cell in the nervous system that process and transmit information by electrochemical Signal . They are the core components of the brain, the vertebrate spinal cord, the invertebrate ventral nerve cord, and the peripheral nerves....
s (those with only one long process) in the dorsal root ganglion
Dorsal root ganglion

In anatomy and neurology, the dorsal root ganglion is a nodule on a dorsal root that contains cell bodies of neurons in afferent nerve spinal nerves....
 have axons that lead from the skin
Skin

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
 into the dorsal spinal cord
Spinal cord

The spinal cord is a long, thin, tubular bundle of neuron and glia that extends from the brain. The brain and spinal cord together make up the central nervous system....
 where they synapse with secondary neurons in the marginal nucleus. These secondary neurons are called tract cells.

The axons of the tract cells cross over (decussate) to the other side of the spinal cord via the anterior white commissure
Anterior white commissure

The anterior white commissure, also known as the alba anterior medullae spinalis, is a bundle of nerve fibers which cross the midline of the spinal cord just anterior to the gray commissure ....
, and to the anterolateral corner of the spinal cord (hence the spinothalamic tract being part of the anterolateral system
Anterolateral system

In the nervous system, the anterolateral system is an ascending pathway that conveys pain, temperature , and crude touch from the periphery to the brain....
). The axons travel up the length of the spinal cord into the brainstem. Pain travels through spinothalamic tracts, and crosses over in the spinal cord at the point it enters, and then travels up contralaterally.

Traveling up the brainstem, the tract moves dorsally. The neurons ultimately synapse with third-order neurons in several nuclei of the thalamus -- including the medial dorsal, ventral posterior lateral, and ventral medial posterior nuclei. From there, signals go to the cingulate cortex
Cingulate cortex

The cingulate cortex is a part of the brain situated in the medial aspect of the Cerebral cortex. It is extended from the corpus callosum below to the cingulate sulcus above, at least anteriorly....
, the primary somatosensory cortex, and insular cortex
Insular cortex

The insular cortex is a structure of the human brain. It lies deep to the brain's lateral surface, within the lateral sulcus which separates the temporal lobe and the parietal lobe dorsally....
 respectively.

Lesions


Unilateral lesion usually causes contralateral anaesthesia (loss of pain and temperature). Anaesthesia will normally begin 1-2 segments below the level of lesion, affecting all caudal body areas. This is clinically tested by using pin pricks.

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