Vagus nerves: anatomy, function, and clinical applications

Vagus nerve (commonly known as the pneumogastric nerve) is a cranial nerve that is connected to the heart and the digestive tract. The nerve is the tenth nerve in the cranium is one of the most important nerves associated with speech. The term "vagus" is taken from Latin and it means "wandering." The nerve got its name as a consequence of the fact that it appears to wander from its initial location in the brain stem to the splenic fixture in the colon.

It's emerging from the brainstem at the medulla, below the glossopharyngeal and accessory nerves. The nerve is similar to several rootlets which come together in two roots exiting the cranium by going through the jugular foramen. "Its two sensory ganglia, the superior (jugular) and inferior (nodosum), are located on the nerve within the jugular fossa of the petrous temporal bone, which, together with the occipital bone, forms the jugular foramen." (Langmore, 27)

The vagus nerve is particularly long and its several branches serve a series of body parts such as the heart, larynx, and velum. Motor speech production is associated with three branches of this nerve:

The pharyngeal branch

The external superior laryngeal nerve branch

The recurrent nerve branch

The vagus nerve is responsible for providing sensory innervation to the pharynx, as it goes through the pharyngeal branch and pharyngeal plexus. When considering its location in the neck, the vagus nerve can be identified by looking at the point between the internal jugular vein and the internal carotid artery. The nerve then goes down straight through the carotid sheet.

The vagus nerve triggers autonomic innervation to glands in the pharyngeal mucosa. The nerve also provides motor innervation, as it goes through the pharyngeal plexus and reaches all the muscles in the velopharynx and pharynx, with the only muscle that it does not reach being the stylopharyngeal muscle.