Course of vagus nerve with branches

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Vagus Nerve (CN X) - Course and Branches

The vagus nerve takes its name from the Latin vagus ("wandering") due to its extensive course from the brainstem to the abdomen. It is the longest cranial nerve and the nerve of the 4th branchial arch.

Fiber Components

The vagus carries five types of fibers:

GSA (General Somatic Afferent): sensation from larynx, laryngopharynx, auricle, external acoustic meatus, posterior cranial fossa dura
GVA (General Visceral Afferent): from aortic chemoreceptors/baroreceptors, esophagus, bronchi, lungs, heart, foregut and midgut viscera (reflex sensations, not pain)
SA (Special Afferent): taste near epiglottis and pharynx
GVE (General Visceral Efferent): parasympathetic to smooth muscle/glands of pharynx, larynx, and thoraco-abdominal viscera (foregut and midgut)
BE (Branchial/Special Visceral Efferent): motor to palatoglossus, soft palate muscles (except tensor veli palatini), pharyngeal constrictors (except stylopharyngeus), and all laryngeal muscles

Origin

Arises as 6-8 rootlets from the posterolateral (anterolateral) surface of the medulla oblongata, just inferior to the glossopharyngeal nerve (CN IX) rootlets, dorsal to the inferior olive
The cranial root of CN XI joins the vagus at the jugular foramen and contributes motor fibers to the pharyngeal and laryngeal muscles innervated by the vagus

Two Sensory Ganglia

At/near the jugular foramen lie two enlargements:

Superior (jugular) ganglion - located in the jugular foramen; contains cell bodies for somatic afferent fibers (meningeal and auricular branches)
Inferior (nodose) ganglion - just distal to the foramen; contains cell bodies for visceral afferent fibers of all other branches

Course and Branches by Region

1. Cranial/Intracranial Portion

The rootlets cross the posterior cranial fossa and converge into the vagus nerve as they enter the jugular foramen. CN IX, CN X, and CN XI all pass through the middle compartment of the jugular foramen together.

Branches given off here:

Meningeal branch: re-enters the cranium to supply dura mater of the posterior cranial fossa
Auricular branch (Arnold's nerve): passes between the mastoid process and tympanic plate; supplies the tympanic membrane, skin of the posterior pinna, and the posterior external acoustic meatus. Clinically responsible for referred otalgia and the ear-cough reflex (coughing on ear syringing).

2. Cervical Course

After exiting the skull, the vagus descends in the carotid sheath, initially medial to the internal jugular vein (IJV) and internal carotid artery (ICA), then - as it descends - lying posteriorly between the IJV (lateral) and the common carotid artery (medial).

Branches in the neck:

Branch	Origin	Course & Supply
Auricular branch	Superior ganglion	Arnold's nerve - see above
Pharyngeal branch	Inferior ganglion	Passes between internal and external carotid arteries to join the pharyngeal plexus (with CN IX + sympathetics); supplies all pharyngeal constrictors and soft palate muscles except tensor veli palatini and stylopharyngeus
Carotid body branch		Supplements CN IX branches to the carotid body chemoreceptors
Superior laryngeal nerve	Inferior ganglion	Descends medial to ICA and ECA; at the level of the hyoid divides into:
- Internal laryngeal nerve		Pierces thyrohyoid membrane with superior laryngeal artery; sensory to laryngeal mucosa above the vocal folds, piriform fossa, cervical esophagus and trachea
- External laryngeal nerve		Runs with the superior thyroid artery on the inferior pharyngeal constrictor; motor to cricothyroid (the only intrinsic laryngeal muscle NOT supplied by the recurrent laryngeal nerve)
Cervical cardiac branches (x2)		Superior branch: arises just below superior laryngeal nerve, passes posteromedial to carotid sheath; Inferior branch: arises at root of neck just above 1st rib; both right cardiac branches + superior left cardiac branch join the deep cardiac plexus; left inferior cardiac branch joins the superficial cardiac plexus
Right recurrent laryngeal nerve	Right vagus as it crosses anterior to right subclavian artery	Hooks posterior to the subclavian artery and ascends in the tracheo-esophageal groove; gives tracheal, esophageal, and pharyngeal branches; terminates as inferior laryngeal nerve - motor to all intrinsic laryngeal muscles except cricothyroid, sensory to subglottic mucosa

Note on the right RLN: In ~1% of individuals it takes a non-recurrent course (associated with an aberrant right subclavian artery/arteria lusoria).

Vagus nerve in the neck - distribution and proximal anatomy at skull base

Vagus nerve in the neck - Fischer's Mastery of Surgery, 8th ed.

3. Thoracic Course

Right vagus nerve:

Enters the superior mediastinum lying between the right brachiocephalic vein and the brachiocephalic trunk
Descends toward the trachea, crosses its lateral surface
Is crossed by the arch of the azygos vein before reaching the esophagus
Passes posterior to the root of the right lung
Descends on the posterior surface of the esophagus, contributing to the esophageal plexus - forming the posterior vagal trunk

Left vagus nerve:

Enters the superior mediastinum posterior to the left brachiocephalic vein, between the left common carotid and left subclavian arteries
Lies deep to the mediastinal parietal pleura
Crosses the left side of the arch of the aorta
At the inferior margin of the arch, just lateral to the ligamentum arteriosum, gives off the left recurrent laryngeal nerve
The left RLN loops under the arch of the aorta, ascends in the tracheo-esophageal groove, and enters the neck to terminate in the larynx
The left vagus then passes posterior to the root of the left lung and reaches the esophagus, contributing to the anterior vagal trunk

Right vagus nerve passing through the superior mediastinum

Right vagus nerve in the superior mediastinum - Gray's Anatomy for Students

Thoracic branches:

Thoracic cardiac branches: from both vagi, join the deep/superficial cardiac plexuses
Pulmonary branches: form the pulmonary plexuses at the roots of the lungs; supply the bronchi and lungs
Esophageal branches: form the esophageal plexus around the lower esophagus (left vagus = anterior surface; right vagus = posterior surface)

The plexus around the esophagus reconstitutes as:

Anterior vagal trunk (mainly left vagus fibers)
Posterior vagal trunk (mainly right vagus fibers)

Both trunks enter the abdomen through the esophageal hiatus of the diaphragm at the level of T10.

4. Abdominal Course and Branches

Anterior vagal trunk (mainly left vagus):

Runs on the anterior surface of the esophagus/cardia
Gives off the hepatic branch(es) - travel in the hepatogastric ligament to the porta hepatis; descending branches supply the pylorus, pyloric sphincter, pancreas, and 1st part of duodenum
Divides into gastric, pyloric, and celiac branches
Anterior gastric branches: supply cardia, fundus, and anterior stomach wall
Principal anterior nerve of the lesser curvature (Latarjet's nerve): the longest gastric branch running along the lesser curvature with the left gastric artery to the pylorus, terminating as "crow's foot" branches (3-4 terminal branches)
Pyloric branches (usually two): one travels in the lesser omentum, the other from the nerve of Latarjet to the pyloric antrum

Posterior vagal trunk (mainly right vagus):

Runs on the posterior surface of the esophagus
Posterior gastric branches: supply the posterior fundus, body, and pyloric antrum (fewer and terminates more proximally than the anterior nerve)
Celiac branches: the main branch of the posterior trunk; passes to the celiac plexus and through it supplies the small intestine up to the left colic flexure (splenic flexure), plus pancreas, kidneys, and adrenals via the renal plexus
Right vagus also gives a branch directly to the celiac plexus continuing posteriorly along the lesser curvature

Summary Table

Region	Key Branches
Cranial (intracranial)	Meningeal branch, Auricular branch (Arnold's nerve)
Cervical	Pharyngeal branch (pharyngeal plexus), Carotid body branch, Superior laryngeal nerve (internal + external), Cervical cardiac branches (x2), Right recurrent laryngeal nerve
Thoracic	Left recurrent laryngeal nerve, Thoracic cardiac branches, Pulmonary branches, Esophageal plexus (forms anterior + posterior vagal trunks)
Abdominal	Esophageal branches, Gastric branches, Hepatic branches, Pyloric branches, Celiac branches, Renal branches, Intestinal branches (to left colic flexure)

Clinically Important Points

Left RLN loops around the arch of the aorta at the ligamentum arteriosum - vulnerable in mediastinal masses, aortic aneurysm, bronchial/esophageal carcinoma
Right RLN loops around the right subclavian artery - vulnerable in thyroid/parathyroid surgery; non-recurrent course in ~1% (associated with aberrant subclavian)
External laryngeal nerve runs with the superior thyroid artery - at risk during thyroid ligation, causing loss of cricothyroid function (voice pitch changes)
Arnold's nerve (auricular branch) stimulation explains: referred otalgia from laryngeal/esophageal pathology, and cough reflex triggered by ear syringing (Arnold's ear-cough reflex)
Beahr's triangle (landmark for RLN): bounded by common carotid artery laterally, inferior thyroid vessels superiorly, and RLN medially
Vagotomy (truncal/selective/highly selective) targets different levels of vagal supply to reduce gastric acid secretion
The vagus provides parasympathetic supply to gut up to the left (splenic) colic flexure - beyond this, the pelvic splanchnic nerves (S2-S4) take over

Sources: Gray's Anatomy for Students, Fischer's Mastery of Surgery 8th ed., Scott-Brown's Otorhinolaryngology Head & Neck Surgery

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