Solitary nucleus

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.

Solitary nucleus

nucleus tractus solitarii medullae oblongatae

Gustatory (taste) sensation from the facial nerve (CN VII) via the (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).

chorda tympani

Chemoreceptors and mechanoreceptors of the general visceral afferent pathway (GVA) from the 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).

carotid body

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. Additional minor GVA input from the nasal cavity, soft palate and sinus cavities enters via the facial nerve.^[4]

[3]

Function[edit]

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.

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.

Solitary nucleus