Solitary nucleus

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Solitary nucleus
cranial nerve nuclei schematically represented; dorsal view. Motor nuclei in red; sensory in blue.
Transverse section of medulla oblongata of human embryo.
Details
Identifiers
Latinnucleus tractus solitarii medullae oblongatae
MeSHD017552
NeuroNames742
NeuroLex IDbirnlex_1429
TA98A14.1.04.230
TA26008
FMA72242
Anatomical terms of neuroanatomy]

The solitary nucleus (also called nucleus of the solitary tract, nucleus solitarius, or nucleus tractus solitarii (SN or NTS))[1][2] is a series of sensory nuclei (clusters of nerve cell bodies) forming a vertical column of grey matter in the medulla oblongata of the brainstem. It receives general visceral and/or special visceral inputs from the facial nerve (CN VII), glossopharyngeal nerve (CN IX) and vagus nerve (CN X); it receives and relays stimuli related to taste and visceral sensation. It sends outputs to various parts of the brain, such as the hypothalamus, thalamus, and reticular formation. Neuron cell bodies of the SN are roughly somatotopically arranged along its length according to function.

Neuroanatomy

The nucleus solitarius is a series of purely sensory nuclei forming a vertical column of grey matter embedded within the medulla oblongata. Through the center of the SN runs the solitary tract, a white bundle of nerve fibers, including fibers from the cranial nerves VII, IX, and X.[1][2]

Cell bodies of the SN are roughly somatotopically arranged along its length according to function: for instance, cells involved in taste are located in the rostral part, while those receiving information from cardio-respiratory and gastrointestinal processes are found in the caudal part.[1][2]

The SN projects to - among other regions - the reticular formation, parasympathetic preganglionic neurons, hypothalamus and thalamus, forming circuits that contribute to autonomic regulation.[1][2]

Afferents

  • Gustatory (taste) sensation from the facial nerve (CN VII) via the chorda tympani (from anterior 2/3 of the tongue), glossopharyngeal nerve (CN IX) (from posterior 1/3) and vagus nerve (CN X) (from small area on the epiglottis).
  • Chemoreceptors and mechanoreceptors of the general visceral afferent pathway (GVA) from the carotid body and carotid sinus via (the carotid sinus nerve of) the glossopharyngeal nerve (CN IX), and from aortic bodies and sinoatrial node via the vagus nerve (CN X).
  • Chemoreceptors and mechanoreceptors of the general visceral afferent pathway (GVA) with endings located in the heart, lungs, airways, gastrointestinal system, pharynx, and liver via the glossopharyngeal and vagus nerves. Organ specific regions of neuronal architecture are preserved in the solitary nucleus.[3] Additional minor GVA input from the nasal cavity, soft palate and sinus cavities enters via the facial nerve.[4]

Efferents

The solitary nucleus projects to a large number of other regions of the brain including the

parabrachial area, locus coeruleus, dorsal raphe nucleus, and other visceral motor or respiratory networks).[5]

The stimuli from the SN to the parabrachial area originate in the oral cavity and gastrointestinal tract. The pathways for gastric and gustatory (taste) processes are believed to terminate in different subdivisions of the parabrachial area, but still interact in the SN.

bed nucleus of the stria terminalis.[8][9]

Function

Afferents of the SN mediate the

gag reflex, the carotid sinus reflex, the aortic reflex, the cough reflex, the baroreflex and chemoreceptor reflexes, several respiratory reflexes and reflexes within the gastrointestinal system regulating motility
and secretion.

Neurons which transmit signals about the gut wall, the stretch of the

lungs, and the dryness of mucous membranes
also innervate the SN. The first central neurons within the SN can participate in simple autonomic reflexes.

Additional images

  • Section of the medulla oblongata at about the middle of the olive.
    Section of the medulla oblongata at about the middle of the olive.
  • Primary terminal nuclei of the afferent (sensory) cranial nerves schematically represented; lateral view.
    Primary terminal nuclei of the afferent (sensory) cranial nerves schematically represented; lateral view.

See also

References

  1. ^
    ISBN 978-0-7817-4677-9
    . Retrieved 22 January 2013.
  2. ^
    ISBN 978-1-60327-455-5
    . Retrieved 22 January 2013.
  3. PMID 36045291
    .
  4. PMID 30252375. Retrieved 2018-10-27. {{cite book}}: |work= ignored (help
    )
  5. ISBN 978-0-205-66627-0
    .
  6. S2CID 28772859
    .
  7. S2CID 33660719
    .
  8. S2CID 9384374
    .
  9. PMID 18853414
    .

External links
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