Glossopharyngeal and Vagus Nerves Overview

Glossopharyngeal Nerve (IX)

• Somatic motor: stylopharyngeus muscle
• Somatic sensory: pharynx, palatine tonsil, and posterior part of tongue
• Parasympathetic secretomotor: parotid gland (inferior salivatory nucleus - lesser petrosal nerve - otic ganglia & hitchhike on auriculotemporal nerve)
• Special sensation: taste on the posterior 1/3 of the tongue
• Attached by 3 or 4 filaments to upper part of the medulla oblongata, in the groove between olive and inferior peduncle.
• Emerges in the neck between the internal carotid artery (ICA) and internal jugular vein (IJV)
• Descends in front of the carotid artery
• Passes medial to the styloid process and styloid muscles
• Runs laterally and forwards around the stylopharyngeus
• Pierces the wall of the pharynx between the superior and middle constrictors
• Passes deep to the stylohyoid ligament and to the posterior free edge of the hyoglossus muscle

Vagus Nerve (X)

• Motor and sensory to larynx and pharynx
• Parasympathetic fibers to thoracic cavity and gastrointestinal tract (GIT)
• Contributes to the pharyngeal, esophageal, and cardiac plexus
• Exits the jugular foramen accompanied by the accessory nerve (XI)
• In the neck, the vagus descends vertically in the carotid sheath
• Lies between the internal jugular vein (IJV) and internal carotid artery (ICA)
• At the level of the upper border of the thyroid cartilage, it lies between the internal jugular vein (IJV) and common carotid artery (CCA)

Vagus Nerve (X) Branches

• Pharyngeal
  • Descends to the middle constrictor where it forms the pharyngeal plexus
  • Supplies the muscles of the pharynx and soft palate (except tensor veli palatini, which is supplied by the mandibular nerve via the otic ganglion)
• Carotid Sinus
• Superior Laryngeal Nerve
  • Arises from the caudal ganglion of the vagus nerve
  • Descends on the wall of the pharynx to the middle constrictor where it divides into internal and external branches
    • Internal Branch: Sensory to the supravocal half of the larynx, pharynx, epiglottis, and adjacent part of the tongue
    • Runs in the gap between the middle and inferior constrictors
    • Passes deep to the thyrohyoid membrane, accompanied by the superior laryngeal artery
    • Supplies the mucous membrane of the larynx above the vocal cords, the epiglottis, the vallecula, the aryepiglottic folds, and the posterior part of the tongue
    • Receives sensory fibers from the laryngeal mucosa, including the vocal cords
    • Communicates with the external branch and may send a few sensory fibers to the pharynx
    • Ends on the mucous membrane of the laryngeal ventricle and the upper part of the larynx
    • Sends filaments to the mucous membrane of the back part of the tongue
    • Has a small branch that runs with the epiglottis to the thyroid cartilage
    • May supply the epiglottic mucous membrane
    • Passes between the superior and middle constrictors of the pharynx
    • May send a twig by the side of the superior laryngeal artery to the pharyngeal mucous membrane
    • Ends as the recurrent laryngeal nerve
    • Communicates with the external branch of the superior laryngeal nerve
    • Sends small filaments to the mucous membrane of the back of the tongue
    • Receives a twig from the vagus nerve.
    • Passes with the inferior laryngeal artery
    • Supplies all the intrinsic muscles of the larynx, except the cricothyroid muscle
    • Runs in a groove on the posterior surface of the thyroid cartilage
    • Receives a twig from the external laryngeal nerve (branch of the superior laryngeal nerve)
    • Supplies all the intrinsic muscles of the larynx
    • Receives a twig from the external laryngeal nerve
    • Runs in a deep groove on the posterior surface of the thyroid cartilage
    • Gives branches to mucous membrane of the larynx below the vocal cords
    • Runs with the inferior laryngeal artery
    • Gives branches to the mucous membrane of the larynx below the vocal cords
    • Runs in a groove on the posterior surface of the thyroid cartilage
    • Gives branches to the mucous membrane of the larynx
    • Supplies all the muscles of the larynx, except the cricothyroid muscle
    • Receives a twig from the external laryngeal nerve
    • Runs in a deep groove on the posterior surface of the thyroid cartilage
    • Runs with the inferior laryngeal artery
    • Gives branches to the mucous membrane of the larynx
    • Supplies all the muscles of the larynx, except the cricothyroid muscle
    • Receives a twig from the external laryngeal nerve
    • Runs in a deep groove on the posterior surface of the thyroid cartilage
    • Runs in a groove on the posterior surface of the thyroid cartilage
    • Supplies all the muscles of the larynx, except the cricothyroid muscle.
    • Runs in a deep groove on the posterior surface of the thyroid cartilage
  • EXTERNAL BRANCH: Runs with the superior thyroid vessels to supply the cricothyroid muscle, the superior constrictor of the pharynx, and some of the muscles below the hyoid bone.
• Cardiac
  • The cardiac branches of the vagus nerve run to the heart with the sympathetic cardiac nerves to form the cardiac plexus
  • Receive contributions from the pharyngeal plexus, and supply the heart and pericardium.
• Esophageal
  • The esophageal branches of the vagus nerve run to the esophagus with the sympathetic nerves to form the esophageal plexus.
• Branches to Thoracic Viscera
  • The vagus nerve's contribution to the pulmonary plexus supplies the lungs
  • Its contribution to the hepatic plexus supplies the liver, gallbladder, biliary duct, and duodenum

Accessory Nerve (XI)

• Motor to sternocleidomastoid and trapezius muscles
• Has a cranial root and a spinal root
• The spinal root: forms the major part of the nerve, originates from the cervical spinal cord (C1 to C5), and ascends through the foramen magnum
• Cranial root: arises from the medulla oblongata and joins the spinal root in the neck
• The spinal root: joins the cranial root to form the accessory nerve
• The cranial root: primarily supplies the vagus nerve
• The spinal root emerges from the spinal cord between the posterior root of the first cervical nerve and the anterior root of the first cervical nerve
• It then enters the skull via the foramen magnum.
• The accessory nerve is often described as consisting of a cranial and a spinal root, although it’s technically a
• The accessory nerve is formed by the union of the cranial and spinal roots.
• It exits the skull via the jugular foramen.
• Descends in the neck, and lies between the internal jugular vein (IJV) and the internal carotid artery (ICA)
• It supplies the sternocleidomastoid and trapezius muscles
• Its branches to the sternocleidomastoid muscle join the nerve just below the jugular process of the temporal bone
• **Its branches to the trapezius muscle arise from the nerve at the posterior border of the sternocleidomastoid muscle. **

Hypoglossal Nerve (XII)

• Motor to the muscles of the tongue
• Originates from the medulla oblongata
• It leaves the skull through the hypoglossal canal,
• descends vertically in the neck,
• runs lateral to the internal carotid artery (ICA), and lies between the internal jugular vein (IJV) and the internal carotid artery (ICA).
• It loops around the occipital artery and then passes deep to the digastric and stylohyoid muscles
• It then passes superior to the hyoglossus muscle and divides into its terminal branches.
• It runs across the floor of the mouth, supplying all the intrinsic muscles of the tongue.
• It gives filaments to the geniohyoid muscle and the genioglossus muscle.
• It has connections with the vagus nerve, the glossopharyngeal nerve, the first cervical nerve, and the sympathetic trunk,
• The hypoglossal nerve: is one of the 12 pairs of cranial nerves, and is motor in nature

This quiz covers the anatomical and functional aspects of the Glossopharyngeal (IX) and Vagus (X) nerves, including their sensory and motor components. Test your understanding of their pathways, innervations, and clinical significance. Perfect for students of anatomy and neuroscience.