Reticulospinal tract

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Brain: Reticulospinal tract

Reticulospinal tract is labeled in red, near center in figure (text tag at left).
NeuroNames	hier-802
NeuroLex ID	birnlex_1471

The reticulospinal tract (or anterior reticulospinal tract) is an extrapyramidal motor tract which travels from the reticular formation.

1 Functions
2 Components
3 Clinical significance
4 See also
5 External links

[edit] Functions

1. Integrates information from the motor systems to coordinate automatic movements of locomotion and posture.

2. Facilitates and inhibits voluntary movement, influences muscle tone.

3. Mediates autonomic functions

4. Modulates pain impulses

5. Influences blood flow to lateral geniculate

[edit] Components

The tract is divided into two parts, the medial (or pontine) and lateral (or medullary) reticulospinal tracts (MRST and LRST).

The MRST is responsible for exciting anti-gravity, extensor muscles. The fibers of this tract arise from the caudal pontine reticular nucleus and the oral pontine reticular nucleus and project to the lamina VII and lamina VIII of the spinal cord (BrainInfo)

The LRST is responsible for the inhibiting excitatory axial extensor muscles of movement. The fibers of this tract arise from the medullary reticular formation, mostly from the gigantocellular nucleus, and descend the length of the spinal cord in the anterior part of the lateral column. The tract terminates in the gray spinal laminae (BrainInfo).

The sensory tract conveying information in the opposite direction is known as the "spinoreticular tract".

[edit] Clinical significance

If the superior colliculus is damaged, it is called decerebration and causes decerebrate rigidity.

The reticulospinal tracts also provide a pathway by which the hypothalamus can control sympathetic thoracolumbar outflow and parasympathetic sacral outflow.

[edit] See also

Upper motor neuron

[edit] External links

BrainInfo reticulospinal tract [1], pontine reticulospinal tract [2], and medullary reticulospinal tract [3]</a>.
http://www.lib.mcg.edu/edu/eshuphysio/program/section8/8ch6/s8ch6_29.htm
http://www.mona.uwi.edu/fpas/courses/physiology/neurophysiology/The%20Reticulospinal%20Pathway.htm

Anatomy of torso (primarily): the spinal cord (TA 14.1.02, GA 9.749)

External, dorsal

Posterior median sulcus · Posterolateral sulcus

Grey matter/
Rexed laminae

I–VI: Posterior horn	I: Marginal nucleus · II: Substantia gelatinosa of Rolando · III+IV: Nucleus proprius · Spinal lamina V · Spinal lamina VI

VII: Lateral horn	Intermediolateral nucleus · Posterior thoracic nucleus

VIII–IX: Anterior horn	Interneuron · Alpha motor neuron (Onuf's nucleus)

X: Other	Central gelatinous substance · Gray commissure Central canal · Terminal ventricle

White matter

somatic/ ascending (blue)	Posterior/PCML: touch: Gracile · Cuneate Lateral: proprioception: Spinocerebellar (Dorsal, Ventral) · pain/temp: Spinothalamic (Lateral, Anterior) · Posterolateral (Lissauer) · Spinotectal Spinoreticular tract · Spino-olivary tract

motor/ descending (red)	Lateral: Corticospinal (Lateral) · Ep (Rubrospinal, Olivospinal) Anterior: Corticospinal (Anterior) · Ep (Vestibulospinal, Reticulospinal, Tectospinal)

both	Anterior white commissure

External, ventral

Anterior median fissure · Anterolateral sulcus

External, general

Cervical enlargement · Lumbar enlargement · Conus medullaris · Filum terminale · Cauda equina

M: CNS

anat(n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp

noco(m/d/e/h/v/s)/cong/tumr, sysi/epon, injr

proc, drug(N1A/2AB/C/3/4/7A/B/C/D)

Human brain, rhombencephalon, metencephalon: pons (TA A14.1.05.101–604, GA 9.785)

Dorsal/
(tegmentum)

Surface	Cerebellopontine angle · Superior medullary velum · Sulcus limitans · Medial eminence · Facial colliculus

White: Sensory/ascending	Trapezoid body/VIII · Trigeminal lemniscus (Dorsal trigeminal tract, Ventral trigeminal tract) · Medial lemniscus · Lateral lemniscus MLF, III, IV and VI: Vestibulo-oculomotor fibers Anterior trigeminothalamic tract · Central tegmental tract

White: Motor/descending	ICP (Vestibulocerebellar tract) MLF, III, IV and VI: Vestibulospinal tract (Medial vestibulospinal tract, Lateral vestibulospinal tract)

Grey: Cranial nuclei	afferent: GSA: Principal V/Spinal V · VIII-c (Dorsal, Anterior)/VIII-v (Superior) efferent: SVE: Motor V · VII · GSE: VI · GVE: VII: Superior salivary nucleus

Other grey	Apneustic center · Pneumotaxic center (Medial parabrachial nucleus) · Lateral parabrachial nucleus · Superior olivary nucleus · Caerulean nucleus

Ventral/
(base)

Grey	Pontine nuclei

White: Motor/descending	Corticospinal tract · Corticobulbar tract · Corticopontine fibers MCP (Pontocerebellar fibers)

Surface	Basilar sulcus

Other grey: Raphe/
reticular

Reticular formation (Caudal, Oral, Tegmental, Paramedian) · Raphe nuclei (Median)

M: CNS

anat(n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp

noco(m/d/e/h/v/s)/cong/tumr, sysi/epon, injr

proc, drug(N1A/2AB/C/3/4/7A/B/C/D)

Brain and spinal cord: neural tracts and fasciculi

Sensory/
ascending

PCML

1°: Pacinian corpuscle/Meissner's corpuscle → Gracile fasciculus/Cuneate fasciculus → Gracile nucleus/Cuneate nucleus

2°: → sensory decussation/arcuate fibers (Posterior external arcuate fibers, Internal arcuate fibers) → Medial lemniscus/Trigeminal lemniscus → Thalamus (VPL, VPM)

3°: → Posterior limb of internal capsule → Postcentral gyrus

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° (Spinotectal tract → Superior colliculus of Midbrain tectum)

Slow/medial	1° (Group C nerve fiber → Spinoreticular tract → Reticular formation) → 2° (MD of Thalamus) → 3° (Cingulate cortex)

Motor/
descending

Pyramidal	flexion: Primary motor cortex → Posterior limb of internal capsule → Decussation of pyramids → Corticospinal tract (Lateral, Anterior) → Neuromuscular junction

Extrapyramidal	flexion: Primary motor cortex → Genu of internal capsule → Corticobulbar tract → Facial motor nucleus → Facial muscles flexion: Red nucleus → Rubrospinal tract extension: Vestibulocerebellum → Vestibular nuclei → Vestibulospinal tract extension: Vestibulocerebellum → Reticular formation → Reticulospinal tract Midbrain tectum → Tectospinal tract → muscles of neck

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) 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) nigrostriatal pathway: Pars compacta → Striatum

Cerebellar

Afferent

Vestibular nucleus → 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

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 nucleus

Bidirectional:
Spinocerebellar

Unc. prop.	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)

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)