Vagus Nerve: Nuclei, Anatomy, and Function

Overview of the Vagus Nerve

• The vagus nerve's nuclei of origin and the muscles it supplies are key topics.
• The functions of the superior and recurrent laryngeal nerves are important.
• The roles of the internal and external laryngeal nerves are also discussed.

Nuclei of Origin

• Motor, sensory, and parasympathetic functions are carried out by the vagus nerve.
• The nucleus ambiguus and the dorsal nucleus are the two main nuclei from which the vagus nerve originates.
• Motor functions are the responsibility of the nucleus ambiguus.
• Parasympathetic functions are the responsibility of the dorsal nucleus.

Anatomical Path

• The medulla oblongata has an upper and a lower part.
• The middle of the medulla oblongata is the upper part.
• The spinal cord connects to the lower part.
• The vagus nerve and glossopharyngeal nerves exit the skull through the foramen magnum.
• Some glossopharyngeal nerve fibers join the vagus nerve after exiting the skull,
• The vagus nerve runs down the neck, supplying various structures.
• Where the medulla oblongata ends, the spinal cord begins.
• The superior and recurrent laryngeal nerves both originate from the vagus nerve.

Vagus Nerve Functions and Branches

• After receiving some sensory fibers from the glossopharyngeal nerve, the vagus nerve supplies several structures.
• Structures supplied include the greater omentum and the transverse colon.
• The vagal nerve complex is formed by both the nucleus ambiguus and the dorsal nucleus.
• Fibers from the nucleus ambiguus supply the pharynx (pharyngeal branch) and larynx (laryngeal branch).
• The pharynx and constrictor muscles receive branches from the superior laryngeal nerve.
• The recurrent laryngeal nerve descends, loops around, and ascends to the larynx.
• The recurrent laryngeal nerve travels through the tracheoesophageal groove.
• It supplies the trachea and esophagus, including the inferior constrictor muscle.

Superior Laryngeal Nerve

• The superior laryngeal nerve branches into the internal and external branches.
• The larynx receives sensory innervation from the internal laryngeal nerve.
• The cricothyroid muscle is supplied by the external laryngeal nerve.
• The thyrohyoid membrane is pierced by the internal laryngeal nerve.

Sensory Supply

• The carotid body and carotid sinus are supplied.
• The vagus nerve extends down to the aortic arch.

Internal and External Laryngeal Nerves

• The internal laryngeal nerve provides a sensory supply to the Larynx.
• It enters the larynx along with the superior laryngeal artery.
• Sensory information above the vocal cords is supplied by the internal laryngeal nerve
• The external laryngeal nerve's supplies motor function to the cricothyroid muscle.
• The recurrent laryngeal nerve supplies all other muscles of the larynx.
• Sensory information below the vocal cords is supplied by the recurrent laryngeal nerve.