Solitary nucleus

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Brain: Solitary nucleus
The cranial nerve nuclei schematically represented; dorsal view. Motor nuclei in red; sensory in blue.
Transverse section of medulla oblongata of human embryo.
Latin tractus solitarius medullae oblongatae
NeuroNames hier-739
MeSH A08.186.211.132.810.406.750
Dorlands/Elsevier t_15/12817166

The solitary nucleus and tract are structures in the brainstem that carry and receive visceral sensation and taste from the facial (VII), glossopharyngeal (IX), vagus (X) cranial nerves, as well as the cranial part of the accessory nerve (XI).

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[edit] Anatomy

The nucleus is located along the length of the medulla (with a small portion in the lower pons). The solitary tract runs in the middle of the nucleus, creating a speck of white matter (axons of the tract), surrounded by grey matter (the nucleus). This stands out on a stained section, which is where the name solitary comes from.

The solitary nucleus is divided into a rostral (towards the top) gustatory nucleus and caudal (towards the bottom) cardiorespiratory nucleus. The cardiorespiratory nucleus can be further divided into a cardiovascular center, which sits at the midline of the nucleus, and a respiratory center, which is located laterally.

[edit] Inputs to the solitary nucleus

As well as taste from nerves VII, IX and X, the solitary nucleus handles information from the carotid (from IX) and aortic bodies and baroreceptors (from X), which controls blood volume.

Information about the gut wall, as well as stretch of the lungs and dryness of mucous membranes, also synapses at the solitary nucleus.

[edit] Outputs from the solitary nucleus

From the solitary nucleus, most information goes to the hypothalamus and cingulate gyrus, as well as to other nuclei in the brainstem (such as visceral motor or respiratory centres). There is not much conscious awareness of visceral sensation (visceral pain is not part of this system), most results are reflexes or unconscious.

[edit] External links

Rhombencephalon (hindbrain)

MYELENCEPHALON/MEDULLA: arcuate nucleus of medulla, solitary nucleus, hypoglossal nucleus, nucleus ambiguus, olivary body, inferior olivary nucleus, cuneate nucleus, accessory cuneate nucleus, gracile nucleus, inferior salivatory nucleus, raphe nuclei (obscurus, magnus, pallidus), area postrema, posterior nucleus of vagus nerve

METENCEPHALON/CEREBELLUM: cerebellar vermis, flocculus, arbor vitae

METENCEPHALON/PONS: pontine tegmentum, superior salivary nucleus, trapezoid body, pontine nuclei (superior olivary nucleus, trigeminal nerve nuclei, abducens nucleus, facial motor nucleus, cochlear nuclei, vestibular nuclei), locus ceruleus, paramedian pontine reticular formation, nucleus centralis superior

FOURTH VENTRICLE: obex, median aperture