en Interposed nucleus

Interposed nucleus
Details
Identifiers
Latin	nucleus interpositus anterior, nucleus interpositus posterior
NeuroLex ID	nlx_anat_20081242
Anatomical terms of neuroanatomy [edit on Wikidata]

The interposed nucleus is the combined paired globose and emboliform nuclei, (deep cerebellar nuclei) on either side of the cerebellum.^[1]^[2] It is located in the roof of the fourth ventricle, lateral to the fastigial nucleus. The emboliform nucleus is the anterior interposed nucleus, and the globose nucleus is the posterior interposed nucleus.^[3]

The interposed nucleus is responsible for coordinating agonist/antagonist muscle pairs, and therefore a lesion in this area causes tremor.

Anatomy

The interposed nucleus is located in the paravermis of the cerebellum.^{[citation needed]}

The interposed nucleus is smaller than the dentate but larger than the fastigial nucleus.^{[citation needed]}

Afferents

The interposed nuclei receives Purkine cell terminal afferents from the paravermal cortex of the spinocerebellum, as well as collaterals of cerebellar afferents from the restiform body and ventral spinocerebellar tract.^[2]

It receives input from the ipsilateral posterior external arcuate fibers (cuneocerebellar tract) and the dorsal spinocerebellar tract, which originate in the accessory cuneate nucleus and the posterior thoracic nucleus, respectively.^{[citation needed]}

Efferents

Afferents from the interposed nuclei leave the cerebellum through superior cerebellar peduncle. They project to:^[2]

contralateral (magnocellular division of) the red nucleus (→ rubrospinal tract). The red nucleus is the main target of tne interposed nuclei.
ipsilateral ventral lateral nucleus of thalamus (→ premotor cortex and primary motor cortex → lateral corticospinal tract).

The rubrospinal and lateral corticospinal tracts are subsequently involved in control of the distal musculature of the extremities.

Function

The interposed nucleus modulates muscle stretch reflexes of proximal limb muscles, and is also required in delayed Pavlovian conditioning.^[4]

References

^ Purves, Dale (2012). Neuroscience (5. ed.). Sunderland, Mass: Sinauer. p. 419. ISBN 9780878936953.
^ ^a ^b ^c Patestas, Maria A.; Gartner, Leslie P. (2016). A Textbook of Neuroanatomy (2nd ed.). Hoboken, New Jersey: Wiley-Blackwell. p. 292. ISBN 978-1-118-67746-9.
^ Haines, Duane (2018). Fundamental neuroscience for basic and clinical applications (Fifth ed.). Philadelphia, PA: Elsevier. p. 396. ISBN 9780323396325.
^ Clark, Robert E.; Zhang, Andrew A.; Lavond, David G. (1992). "Reversible lesions of the cerebellar interpositus nucleus during acquisition and retention of a classically conditioned behavior". Behavioral Neuroscience. 106 (6): 879–888. doi:10.1037/0735-7044.106.6.879. PMID 1335267.

External links

Anatomy of the cerebellum

Surface

Lobes	Anterior lobe Posterior lobe Horizontal fissure Flocculonodular lobe Flocculus Nodule Primary fissure
Medial/lateral	Vermis: anterior Central lobule Culmen Lingula posterior Folium Tuber Uvula Vallecula of cerebellum Hemisphere: anterior Alar central lobule posterior Biventer lobule Cerebellar tonsil

Grey matter

Deep cerebellar nuclei	Dentate interposed Emboliform Globose Fastigial
Cerebellar cortex	Molecular layer Stellate cell Basket cell Purkinje cell layer Purkinje cell Bergmann glia cell = Golgi epithelial cell Fañanas cell Granule cell layer Golgi cell Granule cell Unipolar brush cell Fibers: Mossy fibers Climbing fiber Parallel fiber

White matter

Internal	Arbor vitae
Peduncles	Inferior (medulla): Dorsal spinocerebellar tract Olivocerebellar tract Cuneocerebellar tract Juxtarestiform body (Vestibulocerebellar tract) Trigeminocerebellar fibers Middle (pons): Pontocerebellar fibers Superior (midbrain): Ventral spinocerebellar tract Dentatothalamic tract

Brain and spinal cord: neural tracts and fasciculi

Sensory

DCML

1°:	Pacinian corpuscle/Meissner's corpuscle → Posterior column (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° (Spinomesencephalic 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

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 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

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

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)
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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