The solitary tract is a compact fiber bundle that extends longitudinally through the posterolateral region of the medulla

Medulla oblongata

The medulla oblongata is the lower half of the brainstem. In discussions of neurology and similar contexts where no ambiguity will result, it is often referred to as simply the medulla...

. The solitary tract is surrounded by the nucleus of the solitary tract, and descends to the upper cervical segments of the spinal cord

Spinal cord

The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...

.

Composition

The solitary tract is made up of primary sensory fibers and descending fibers of the vagus

Vagus nerve

The vagus nerve , also called pneumogastric nerve or cranial nerve X, is the tenth of twelve paired cranial nerves...

, glossopharyngeal

Glossopharyngeal nerve

The glossopharyngeal nerve is the ninth of twelve pairs of cranial nerves . It exits the brainstem out from the sides of the upper medulla, just rostral to the vagus nerve...

, and facial nerve

Facial nerve

The facial nerve is the seventh of twelve paired cranial nerves. It emerges from the brainstem between the pons and the medulla, and controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity...

s.

Function

The solitary tract conveys afferent information from stretch receptors and chemoreceptors in the walls of the cardiovascular, respiratory, and intestinal tracts. Afferent fibers from cranial nerves 7

Facial nerve

The facial nerve is the seventh of twelve paired cranial nerves. It emerges from the brainstem between the pons and the medulla, and controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity...

, 9

Glossopharyngeal nerve

The glossopharyngeal nerve is the ninth of twelve pairs of cranial nerves . It exits the brainstem out from the sides of the upper medulla, just rostral to the vagus nerve...

 and 10

Vagus nerve

The vagus nerve , also called pneumogastric nerve or cranial nerve X, is the tenth of twelve paired cranial nerves...

 convey taste (SVA

Special visceral afferent

' refers to afferent nerves that develop in association with the gastrointestinal tract. They carry the special senses of smell and taste . The cranial nerves containing SVA fibers are the olfactory nerve , the facial nerve , the glossopharyngeal nerve and the vagus nerve...

) in its rostral portion, and general visceral sense (GVA

General visceral afferent fibers

The general visceral afferent fibers conduct sensory impulses from the viscera, glands, and blood vessels to the central nervous system. They are considered to be part of the autonomic nervous system...

) in its caudal part. Taste bud

Taste bud

Taste buds contain the receptors for taste. They are located around the small structures on the upper surface of the tongue, soft palate, upper esophagus and epiglottis, which are called papillae. These structures are involved in detecting the five elements of taste perception: salty, sour,...

s in the mucosa of the tongue can also generate impulses in the rostral regions of the solitary tract. The efferent fibers are distributed to the solitary tract nucleus.

Synonyms

There are numerous synonyms for the solitary tract:

• round fasciculus (Latin: fasciculus rotundus)
• solitary fasciculus (Latin: fasciculus solitarius)
• solitary bundle (Latin: funiculus solitarius)
• Gierke respiratory bundle
• Krause respiratory bundle