Anatomy of the Vagus Nerve

authors

Baker, Elliott and Lui, Forshing

url

http://www.ncbi.nlm.nih.gov/books/NBK545209/

See also (88) Central Nervous System: Crash Course Anatomy & Physiology #11 - YouTube

The vagus nerve emerges from four nuclei in the brain.

• dorsal motor nucleus

• nucleus ambiguus

• solitary nucleus

• spinal trigeminal nucleus

The last has a minor input from the vagus nerve. The other three are the main vagal nuclei.

Dorsal Vagal Nucleus

• Originates anterior to the base of the fourth ventricle in the medulla

• general visceral efferent fibers that

  • send parasympathetic signals to the heart and lungs

  • innervate GI smooth muscles and glands.

From Hacking:

The dorsal vagal nucleus, also known as the vagal nucleus, dorsal nucleus of the vagus nerve or the dorsal motor nucleus of the vagus nerve, is a elongated nucleus within the medulla oblongata that provides parasympathetic motor innervation to the viscera of the thorax and abdomen. It is the largest parasympathetic nucleus in the brainstem.

Seen abbreviated as DMV in SpatialOrganizationNeurons.

Nucleus Ambiguus

• In the medullary reticular formation

• Efferent special visceral branchiomotor fibers

  • motor innervation for swallowing and phonation

• fibers emerging from this nucleus also contribute to efferent portions of the glossopharyngeal and spinal accessory nerves.

  So:

  • swallowing

  • phonemes

  • voice

  • neck

Solitary Nucleus, or Nucleus Tractus Solitarius

• vertical column of grey matter in the dorsomedial medulla

  • transected by a bundle of myelinated nerve fibers called the solitary tract

• receives general visceral afferent fibers

  • chemoreceptors and mechanoreceptors of:

    • the carotid body and carotid sinus (innervated by the glossopharyngeal nerve)

    • aortic bodies and sinoatrial nerve (innervated by the vagus nerve)

    • taste information from the enterior two-thirds of the tongue (innervated by a branch of the facial nerve - chorda tympani)

    • taste information fromt he posterior one-third of the tongue (glossopharyngeal nerve)

    • epiglottis (vagus nerve)

• responsible for

  • gag reflex

  • carotid sinus reflex

  • cough reflex