Spinothalamic tract |
Spinothalamic tracts are grouped, in blue at bottom right.
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Diagram of the principal fasciculi of the spinal cord. (Anterior and posterior spinothalamic fasciculus is labeled at bottom left.)
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Details |
Identifiers |
Latin |
Tractus spinothalamicus |
NeuroNames |
ancil-114 |
TA |
A14.1.04.138 |
FMA |
72644 |
Anatomical terms of neuroanatomy
[edit on Wikidata]
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The spinothalamic tract (also known as anterolateral system or the ventrolateral system) 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.
The spinothalamic tract consists of two adjacent pathways: anterior and lateral. The anterior spinothalamic tract carries information about crude touch. The lateral spinothalamic tract conveys pain and temperature.
In the spinal cord, the spinothalamic tract has somatotopic organization. This is the segmental organization of its cervical, thoracic, lumbar, and sacral components, which is arranged from most medial to most lateral respectively.
The pathway decussates at the level of the spinal cord, rather than in the brainstem like the posterior column-medial lemniscus pathway and corticospinal tract.
Contents
- 1 Structure
- 2 Function
- 3 Clinical significance
- 4 Anterolateral system
- 5 See also
- 6 References
- 7 External links
Structure
There are two main parts of the spinothalamic tract (STT):
- The lateral spinothalamic tract transmits pain and temperature.
- The anterior spinothalamic tract (or ventral spinothalamic tract) transmits crude touch and firm pressure.
The spinothalamic tract, like the dorsal column-medial lemniscus tract, uses three neurons to convey sensory information from the periphery to conscious level at the cerebral cortex.
Pseudounipolar neurons in the dorsal root ganglion have axons that lead from the skin into the dorsal spinal cord where they ascend or descend one or two vertebral levels via Lissauer's tract and then synapse with secondary neurons in either the substantia gelatinosa of Rolando or the nucleus proprius. 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, and to the anterolateral corner of the spinal cord (hence the spinothalamic tract being part of the anterolateral system). Decussation usually occurs 1-2 spinal nerve segments above the point of entry. The axons travel up the length of the spinal cord into the brainstem, specifically the rostral ventromedial medulla.
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 posterior medial nuclei. From there, signals go to the cingulate cortex, the primary somatosensory cortex, and insular cortex respectively.
Function
The types of sensory information transmitted via the spinothalamic tract are described as affective sensation. 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.
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-Mesencephalic-Limbic (for affective impact of pain).
Clinical significance
In contrast to the axons of second-order neurons in posterior column-medial lemniscus pathway, the axons of second-order neurons in the spinothalamic tracts cross at every segmental level in the spinal cord. This fact aids in determining whether a lesion is in the brain or the spinal cord. With lesions in the brain stem or higher, deficits of pain perception, touch sensation, and proprioception are all contralateral to the lesion. With spinal cord lesions, however, the deficit in pain perception is contralateral to the lesion, whereas the other deficits are ipsilateral. See Brown-Séquard syndrome.
Unilateral lesions usually cause 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.
Anterolateral system
In the nervous system, the anterolateral system (ALS) is an ascending pathway that conveys pain,[1] temperature (protopathic sensation), and crude touch from the periphery to the brain. It comprises three main pathways:
Name |
Destination |
Function |
spinothalamic tract (lateral and anterior) |
thalamus |
important in the localization of painful or thermal stimuli |
spinoreticular tract |
reticular formation |
causes alertness and arousal in response to painful stimuli |
spinotectal tract |
tectum |
orients the eyes and head towards the stimuli |
See also
This article uses anatomical terminology; for an overview, see Anatomical terminology.
- Rostral ventromedial medulla
- Periaqueductal gray
- Neothalamus
References
- ^ "Chapter 25:Neural Mechanisms of Cardiac Pain: The Anterolateral System". Retrieved 2009-11-26.
External links
Sensory receptors
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Touch |
- Mechanoreceptor
- Vibration
- Light touch
- Pressure
- Stretch
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Pain |
- Free nerve endings – pain
- Nociceptors
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Temperature |
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Proprioception |
- Golgi organ
- Muscle spindle
- Intrafusal muscle fiber
- Nuclear chain fiber
- Nuclear bag fiber
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Other |
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The spinal cord
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General features |
- Cervical enlargement
- Lumbar enlargement
- Conus medullaris
- Filum terminale
- Cauda equina
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Grey matter |
Posterior grey column |
- Marginal nucleus
- Substantia gelatinosa of Rolando
- Nucleus proprius
- Spinal lamina V
- Spinal lamina VI
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Lateral grey column |
- Intermediolateral nucleus
- Posterior thoracic nucleus
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Anterior grey column |
- Interneuron
- Alpha motor neuron
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Other |
- Rexed laminae
- Central gelatinous substance
- Gray commissure
- Central canal
- Terminal ventricle
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White matter |
Sensory |
Posterior |
- Posterior column-medial lemniscus pathway:
- Gracile
- Cuneate
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Lateral: |
- Spinocerebellar
- Spinothalamic
- Posterolateral
- Spinotectal
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- Spinoreticular tract
- Spino-olivary tract
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Motor |
Lateral |
- Corticospinal
- Extrapyramidal
- Rubrospinal
- Olivospinal
- Raphespinal
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Anterior |
- Corticospinal
- Extrapyramidal
- Vestibulospinal
- Reticulospinal
- Tectospinal
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Both |
- Anterior white commissure
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External features |
- Ventral
- Anterior median fissure
- Anterolateral sulcus
- Dorsal
- Posterior median sulcus
- Posterolateral sulcus
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Anatomy of the medulla
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Grey matter |
Cranial nuclei |
afferent: |
- Solitary nucleus
- tract
- Dorsal respiratory group
- Gustatory nucleus
- Vestibular nuclei
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efferent: |
- Hypoglossal nucleus
- Nucleus ambiguus
- Dorsal nucleus of vagus nerve
- Inferior salivatory nucleus
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Dorsal |
- Gracile nucleus
- Cuneate nucleus
- Accessory cuneate nucleus
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Ventral |
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- Ventral respiratory group
- Arcuate nucleus of medulla
- Rostral ventromedial medulla
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White matter |
Dorsal |
- Sensory
- Sensory decussation
- Medial lemniscus
- Juxtarestiform body
- Ascending dorsal longitudinal fasciculus
- Medial longitudinal fasciculus
- Motor
- Descending dorsal longitudinal fasciculus
- Medial longitudinal fasciculus
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Ventral |
- Descending tracts
- Olivocerebellar tract
- Rubro-olivary tract
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Surface |
Front |
- Pyramid
- decussation
- Anterior median fissure
- Anterolateral sulcus
- Olive
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Back |
- Posterior median sulcus
- Posterolateral sulcus
- Area postrema
- Vagal trigone
- Hypoglossal trigone
- Medial eminence
- Inferior cerebellar peduncle
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Grey |
- Reticular formation
- Gigantocellular
- Parvocellular
- Ventral
- Lateral
- Paramedian
- Raphe nuclei
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Anatomy of the pons
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Dorsal/
(tegmentum) |
Surface |
- Cerebellopontine angle
- Superior medullary velum
- Sulcus limitans
- Medial eminence
- Facial colliculus
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White: Sensory |
- Trapezoid body
- Trigeminal lemniscus
- Dorsal trigeminal tract
- Ventral trigeminal tract
- Medial lemniscus
- Lateral lemniscus
- Medial longitudinal fasciculus
- Vestibulo-oculomotor fibers
- Anterior trigeminothalamic tract
- Central tegmental tract
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White: Motor |
- Inferior cerebellar peduncle
- Vestibulocerebellar tract
- Medial longitudinal fasciculus
- Vestibulospinal tract
- Medial vestibulospinal tract
- Lateral vestibulospinal tract
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Grey: Cranial nuclei |
afferent: |
- GSA
- Cochlear nucleus
- Vestibular nuclei
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efferent: |
- SVE: Trigeminal motor nucleus
- Facial motor nucleus
- GSE: Abducens nucleus
- GVE: Superior salivary nucleus
- Inferior salivary nucleus
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Other |
- Apneustic center
- Parabrachial area
- Pneumotaxic center
- Subparabrachial nucleus
- Medial parabrachial nucleus
- Lateral parabrachial nucleus
- Superior olivary nucleus
- Caerulean nucleus
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Ventral/
(base) |
Grey |
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White: Motor/descending |
- Corticospinal tract
- Corticobulbar tract
- Corticopontine fibers
- MCP
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Surface |
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Other grey: Raphe/
reticular |
- Reticular formation
- Caudal
- Oral
- Tegmental
- Paramedian
- Raphe nuclei
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Anatomy of the midbrain
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Tectum
(Dorsal) |
Surface |
- Corpora quadrigemina:
- Inferior colliculus
- Superior colliculus
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Grey matter |
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White: Sensory/ascending |
- Spinotectal tract
- Central tegmental tract
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White: Motor/descending |
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Peduncle
(Ventral) |
Tegmentum |
White: Sensory/ascending |
- Lemnisci
- Ascending MLF
- Vestibulo-oculomotor fibers
- Spinothalamic tract
- Anterior trigeminothalamic tract
- Dentatothalamic tract
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White: Motor/descending |
- Rubrospinal tract
- Rubro-olivary tract
- Descending MLF
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Grey: cranial nuclei |
- GSA
- Mesencephalic- GSE
- Oculomotor nucleus, Trochlear nucleus- GVE
- Edinger–Westphal nucleus
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Grey: other |
- Periaqueductal gray
- Raphe nuclei
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- Ventral tegmental area
- Pedunculopontine nucleus
- Red nucleus
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- Rostral interstitial nucleus of medial longitudinal fasciculus
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Ventricular system |
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Base |
White: Motor/descending |
- Cerebral crus: Corticospinal tract
- Corticobulbar tract
- Corticopontine tract/Frontopontine fibers/Temporopontine fibers
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Grey: Substantia nigra |
- Pars compacta
- Pars reticulata
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Surface |
- Superior cerebellar peduncle
- Interpeduncular fossa
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Anatomy of the diencephalon of the human brain
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Epithalamus |
Surface |
- Pineal gland
- Habenula
- Habenular trigone
- Habenular commissure
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Grey matter |
- Pretectal area
- Habenular nuclei
- Subcommissural organ
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Thalamus |
Surface |
- Stria medullaris of thalamus
- Thalamic reticular nucleus
- Taenia thalami
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Grey matter/
nuclei |
- paired: AN
- Ventral
- Lateral
- Metathalamus
- midline: MD
- Intralaminar
- Midline nuclear group
- Interthalamic adhesion
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White matter |
- Mammillothalamic fasciculus
- Pallidothalamic tracts
- Ansa lenticularis
- Lenticular fasciculus
- Thalamic fasciculus
- PCML
- Medial lemniscus
- Trigeminal lemniscus
- Spinothalamic tract
- Lateral lemniscus
- Dentatothalamic tract
- Acoustic radiation
- Optic radiation
- Subthalamic fasciculus
- Anterior trigeminothalamic tract
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Hypothalamus |
Surface |
- Median eminence/Tuber cinereum
- Mammillary body
- Infundibulum
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Grey matter |
Autonomic zones |
- Anterior (parasympathetic/heat loss)
- Posterior (sympathetic/heat conservation)
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Endocrine |
- posterior pituitary: Paraventricular
- Magnocellular neurosecretory cell
- Parvocellular neurosecretory cell
- Supraoptic
- other: Arcuate (dopamine/GHRH)
- Preoptic (GnRH)
- Suprachiasmatic (melatonin)
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Emotion |
- Lateral
- Ventromedial
- Dorsomedial
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White matter |
- afferent
- Medial forebrain bundle
- Retinohypothalamic tract
- efferent
- Mammillothalamic fasciculus
- Stria terminalis
- Dorsal longitudinal fasciculus
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Pituitary |
- Posterior is diencephalon, but anterior is glandular
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Subthalamus |
- Subthalamic nucleus
- Zona incerta
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Brain and spinal cord: neural tracts and fasciculi
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Sensory/
ascending |
PCML |
1°: |
- Pacinian corpuscle/Meissner's corpuscle → Posterior column (Gracile fasciculus/Cuneate fasciculus) → Gracile nucleus/Cuneate nucleus
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2°: |
- → sensory decussation/arcuate fibers (Posterior external arcuate fibers, Internal arcuate fibers) → Medial lemniscus/Trigeminal lemniscus → Thalamus (VPL, VPM)
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3°: |
- → Posterior limb of internal capsule → Postcentral gyrus
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Anterolateral/
pain |
Fast/lateral |
- 1° (Free nerve ending → A delta fiber) → 2° (Anterior white commissure → Lateral and Anterior Spinothalamic tract → Spinal lemniscus → VPL of Thalamus) → 3° (Postcentral gyrus) → 4° (Posterior parietal cortex)
2° (Spinomesencephalic tract → Superior colliculus of Midbrain tectum)
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Slow/medial |
- 1° (Group C nerve fiber → Spinoreticular tract → Reticular formation) → 2° (MD of Thalamus) → 3° (Cingulate cortex)
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Motor/
descending |
Pyramidal |
- flexion: Primary motor cortex → Posterior limb of internal capsule → Decussation of pyramids → Corticospinal tract (Lateral, Anterior) → Neuromuscular junction
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Extrapyramidal |
flexion: |
- Primary motor cortex → Genu of internal capsule → Corticobulbar tract → Facial motor nucleus → Facial muscles
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flexion: |
- Red nucleus → Rubrospinal tract
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extension: |
- Vestibulocerebellum → Vestibular nuclei → Vestibulospinal tract
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extension: |
- Vestibulocerebellum → Reticular formation → Reticulospinal tract
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- Midbrain tectum → Tectospinal tract → muscles of neck
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Basal ganglia |
direct: |
1° (Motor cortex → Striatum) → 2° (GPi) → 3° (Lenticular fasciculus/Ansa lenticularis → Thalamic fasciculus → VL of Thalamus) → 4° (Thalamocortical radiations → Supplementary motor area) → 5° (Motor cortex)
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indirect: |
1° (Motor cortex → Striatum) → 2° (GPe) → 3° (Subthalamic fasciculus → Subthalamic nucleus) → 4° (Subthalamic fasciculus → GPi) → 5° (Lenticular fasciculus/Ansa lenticularis → Thalamic fasciculus → VL of Thalamus) → 6° (Thalamocortical radiations → Supplementary motor area) → 7° (Motor cortex)
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nigrostriatal pathway: |
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Cerebellar |
Afferent |
- Vestibular nuclei → Vestibulocerebellar tract → ICP → Cerebellum → Granule cell
- Pontine nuclei → Pontocerebellar fibers → MCP → Deep cerebellar nuclei → Granule cell
- Inferior olivary nucleus → Olivocerebellar tract → ICP → Hemisphere → Purkinje cell → Deep cerebellar nuclei
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Efferent |
- Dentate nucleus in Lateral hemisphere/pontocerebellum → SCP → Dentatothalamic tract → Thalamus (VL) → Motor cortex
- Interposed nucleus in Intermediate hemisphere/spinocerebellum → SCP → Reticular formation, or → Cerebellothalamic tract → Red nucleus → Thalamus (VL) → Motor cortex
- Fastigial nucleus in Flocculonodular lobe/vestibulocerebellum → Vestibulocerebellar tract → Vestibular nuclei
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Bidirectional:
Spinocerebellar |
Unconscious
proprioception |
- lower limb → 1° (muscle spindles → DRG) → 2° (Posterior thoracic nucleus → Dorsal/posterior spinocerebellar tract → ICP → Cerebellar vermis)
- upper limb → 1° (muscle spindles → DRG) → 2° (Accessory cuneate nucleus → Cuneocerebellar tract → ICP → Anterior lobe of cerebellum)
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Reflex arc |
- lower limb → 1° (Golgi tendon organ) → 2° (Ventral/anterior spinocerebellar tract→ SCP → Cerebellar vermis)
- upper limb → 1° (Golgi tendon organ) → 2° (Rostral spinocerebellar tract → ICP → Cerebellum)
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