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