Nucleus of solitary tract

At a glance

English

Nucleus of solitary tract

Latin (TA2)

Nucleus tractus solitarii

System

Brain and spinal cord

Region

Head

Side

Paired, left and right

About the nucleus of solitary tract

The nucleus of the solitary tract, also called the solitary nucleus or by its Latin initials NTS, is a column of grey matter running lengthways through the dorsal medulla oblongata, lateral to the dorsal motor nucleus of the vagus. It is purely sensory. Along its centre runs the solitary tract, a compact bundle of incoming fibres from three cranial nerves, which gives the nucleus its name.

Its cells are arranged by function along its length. The upper (rostral) part, sometimes called the gustatory nucleus, receives taste: from the front two-thirds of the tongue through the chorda tympani of the facial nerve, from the back third through the glossopharyngeal nerve, and from the epiglottis region through the vagus. The lower (caudal) part receives general visceral information. This includes signals from chemoreceptors in the carotid and aortic bodies and stretch receptors in the carotid sinus and aortic arch, and from endings in the heart, lungs and airways, pharynx, liver and gut wall, carried in the glossopharyngeal and vagus nerves. A small amount of visceral input from the nose, soft palate and sinuses comes in through the facial nerve.

From the nucleus, information spreads widely. Local connections with the reticular formation, the nucleus ambiguus and the dorsal vagal nucleus close many reflexes within the brainstem, including the gag and cough reflexes, the baroreceptor and chemoreceptor reflexes that steady blood pressure and breathing, lung stretch reflexes and the control of gut movement and secretion. Longer projections reach the parabrachial area of the pons, the locus coeruleus and raphe nuclei, the hypothalamic paraventricular nucleus, the amygdala (its central nucleus), the bed nucleus of the terminal stria and, for taste, the thalamus on the way to the cortex.

It is therefore the main gateway by which the brain learns the state of the internal organs, and damage to it disturbs taste, swallowing and the control of blood pressure and breathing.

Function and supply

Function

Receives taste and general visceral sensation carried by cranial nerves VII, IX and X and relays it to brainstem reflex centres, the hypothalamus, amygdala and thalamus, regulating circulation, breathing and digestion.

Blood supply

Branches of the vertebral artery and the posterior inferior cerebellar artery supplying the dorsal medulla.