The vagus nerve provides an extensive afferent and efferent network of innervation for the viscera and plays a key role as an interface between higher central nervous system (CNS) circuits and the autonomic control circuitry of the brain stem. It is a mixed autonomic nerve (involved in both sympathetic and parasympathetic activity) originating at the medulla oblongata and projecting from the brain stem bilaterally along the neck (bundled with the carotid artery rostrally) and esophagus before branching diffusely to innervate the viscera.
References
Johnson, R. L., & Wilson, C. G. (2018). A review of vagus nerve stimulation as a therapeutic intervention. Journal of inflammation research, 203-213.
The vagus is a cranial nerve, which provides the major bidirectional (motor and sensory) communication between the brain and the body. The vagus is a major component of the parasympathetic branch of the autonomic nervous system. Functionally, specific vagal motor pathways are able to inhibit the reactivity of the sympathetic branch of the autonomic nervous system, while vagal sensory pathways provide a major surveillance portal between the body and the brain.
References
Porges, S. W. (2017). Vagal pathways: Portals to compassion. The Oxford handbook of compassion science, 189-202.