Internal arcuate fibers

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Internal arcuate fibers
Diagram showing the course of the arcuate fibers. (Testut.) 1. Medulla oblongata anterior surface. 2. Anterior median fissure. 3. Fourth ventricle. 4. Inferior olivary nucleus, with the accessory olivary nuclei. 5. Gracile nucleus. 6. Cuneate nucleus. 7. Trigeminal. 8. Inferior peduncles, seen from in front. 9. Posterior external arcuate fibers. 10. Anterior external arcuate fibers. 11. Internal arcuate fibers. 12. Peduncle of inferior olivary nucleus. 13. Nucleus arcuatus. 14. Vagus. 15. Hypoglossal.
Latin	fibrae arcuatae internae
Gray's	subject #187 782
System
MeSH	[1]
Section of the medulla oblongata at about the middle of the olive. (Arcuate fibers labeled at center right.)

Internal arcuate fibers are the axons of second-order neurons contained within the gracile and cuneate nuclei of the medulla oblongata.

These fibers cross (decussate) from one side of the medulla to the other to form the medial lemniscus.

Part of the dorsal column-medial lemniscus system (second neuron), the internal arcuate fibers are important for relaying the sensation of fine touch and proprioception to the thalamus and ultimately to the cerebral cortex.

[edit] External links

• BrainInfo at the University of Washington Hier-792
• Photo at indiana.edu

v·d·e Brain: rhombencephalon (hindbrain)
Metencephalon/ pons	{| class="navbox collapsible nowraplinks" style="margin:auto; background:white;background:white;"
[[[:Template:Fullurl:Template:]] v]·[[[:Template:Fullurl:Template talk:]] d]·[[[:Template:Fullurl:Template:]] e]
Dorsal/ (tegmentum)	surface: Locus ceruleus Trigeminal lemniscus (Dorsal trigeminal tract, Ventral trigeminal tract) cranial nuclei: GSA: Principal V/Spinal V - VIII-c (Dorsal, Anterior)/VIII-v (Lateral, Superior, Medial, Inferior) - SVE: Motor V - VII - GSE: VI - GVE: VII: Superior salivary nucleus MLF, III, IV and VI (vestibulo-oculomotor fibers, medial vestibulospinal tract) sensory/ascending: Trapezoid body/VIII - Superior olivary nucleus Inferior cerebellar peduncle (Vestibulocerebellar tract) motor/descending: Apneustic center • Pneumotaxic center (Medial parabrachial nucleus) - Lateral parabrachial nucleus
Ventral/ (base)	Middle cerebellar peduncles (Pontocerebellar fibers) - Pontine nuclei motor/descending: Corticospinal tract - Corticobulbar tract - Corticopontine fibers
Raphe/reticular	Reticular formation (Caudal, Oral, Tegmental, Paramedian) • Raphe nuclei (Median)

|- style="white-space:nowrap;background:#ddddff;text-align:right;background-color: LightYellow" ! Myelencephalon/
medulla | colspan="1" style="text-align:left;width:100%;font-size:95%;background:#f7f7f7;" | {| class="navbox collapsible nowraplinks" style="margin:auto; background:white;background:white;" |- style="text-align:center;width:100%;"

!colspan="2" |

|- |- style="white-space:nowrap;background:#ddddff;text-align:right;padding-left:0em;padding-right:0em;background-color: LightYellow"

!

| colspan="1" style="text-align:left;width:100%;font-size:95%;" | surface: Posterior median sulcus - Postero-lateral sulcus - Area postrema

cranial nuclei: GVA: VII,IX,X: Solitary/tract • SVA: Gustatory nucleus • GSE: XII  • GVE: IX,X,XI: Ambiguus • SVE: X: Dorsal • IX: Inferior salivatory nucleus - MLF, III, IV and VI

sensory/ascending: Gracile nucleus • Cuneate nucleus (Accessory cuneate nucleus) • Sensory decussation  • Medial lemniscus

motor/descending: Dorsal respiratory group
|- style="white-space:nowrap;background:#ddddff;text-align:right;padding-left:0em;padding-right:0em;background-color: LightYellow"

!

| colspan="1" style="text-align:left;width:100%;font-size:95%;background:#f7f7f7;" | motor/descending: Ventral respiratory group - Pyramid (Motor decussation) - Inferior olivary nucleus (Olivocerebellar tract, Rubro-olivary tract)
surface: Anterior median fissure - Antero-lateral sulcus - Arcuate nucleus of medulla - Olivary body
|- style="white-space:nowrap;background:#ddddff;text-align:right;padding-left:0em;padding-right:0em;background-color: LightYellow"

!

| colspan="1" style="text-align:left;width:100%;font-size:95%;" | Reticular formation (Gigantocellular, Parvocellular, Ventral, Lateral, Paramedian) • Raphe nuclei (Obscurus, Magnus, Pallidus) |} |}

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