Nucleus tractus solitarius

The nucleus of the solitary tract, or NTS (Latin: nucleus tractus solitarii), 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 NTS is divided into a rostral (towards the top) gustatory nucleus and caudal (towards the bottom) region of neurons. Sub regions of the NTS can be related to the distribution of inputs - particularly contacts from cranial primary afferent neurons (see below) related to cardiovascular, respiratory and gastrointestinal functions. There is some degree of localization within the caudal region so that many cardiovascular neurons sit near the midline of the nucleus, and many respiratory related neurons are located laterally within the nucleus.