Anatomy Atlas

Vagus nerve (CN X)

Nervus vagus
Also: CN X · Cranial nerve X · Vagal trunks · Pharyngeal plexus
NerveHigh-yielddraftNeuroEENT

Longest cranial nerve — motor to the palate, pharynx and larynx, and parasympathetic supply to the thoracic and abdominal viscera down to the distal transverse colon. A lesion causes hoarseness, dysphagia and a uvula deviated away from the lesion.

Core anatomy

Origin

Emerges from the postolivary sulcus of the medulla oblongata below CN IX. Nuclei: nucleus ambiguus (motor to pharynx, larynx, palate), dorsal motor nucleus of the vagus (parasympathetic), nucleus of the solitary tract (visceral sensation, taste from the epiglottis), spinal trigeminal nucleus (ear).

Course

Leaves through the jugular foramen (superior and inferior ganglia) → descends in the carotid sheath between and behind the internal/common carotid artery and internal jugular vein → right vagus crosses in front of the right subclavian artery (giving the right recurrent laryngeal nerve) → left vagus crosses the aortic arch (giving the left recurrent laryngeal nerve) → both pass behind the lung roots → form the esophageal plexus → anterior (mainly left) and posterior (mainly right) vagal trunks pass through the esophageal hiatus (T10) → abdominal viscera.

Branches
  • Auricular branch (Arnold nerve) — external ear canal (ear-canal cough reflex)
  • Pharyngeal branches → pharyngeal plexus (pharynx and soft palate)
  • Superior laryngeal nerve — internal (sensation above the vocal folds) and external (cricothyroid)
  • Recurrent laryngeal nerve — all other intrinsic laryngeal muscles
  • Cardiac branches (slow the heart — mainly SA and AV nodes), pulmonary branches (bronchoconstriction, secretion)
  • Esophageal, gastric, hepatic, celiac and renal branches — parasympathetic to the foregut and midgut (to about the distal third of the transverse colon)
Motor

Muscles of the soft palate (except tensor veli palatini — V3), pharynx (except stylopharyngeus — IX), larynx (larynx), palatoglossus, and the upper esophagus. Parasympathetic to the heart, lungs and gut.

Sensory

Laryngopharynx and larynx (cough reflex), part of the external ear, visceral afferents from thoracic and abdominal organs (most vagal fibers are afferent), aortic arch baroreceptors and chemoreceptors.

Relations

In the neck in the carotid sheath; in the thorax, related to the thoracic aorta, esophagus and lung roots; in the abdomen, the trunks lie on the stomach.

Branches

Other structures innervated

Mentioned in

Generated automatically from links in other entries.

Course of the recurrent laryngeal nervesAnterior view of the neck and upper chest, patient's right on the left. Each vagus nerve descends beside the common carotid artery. The right recurrent laryngeal nerve leaves the right vagus in the root of the neck and hooks under the right subclavian artery. The left recurrent laryngeal nerve leaves the left vagus in the thorax and hooks under the aortic arch, just lateral to the ligamentum arteriosum, so it is longer. Both ascend in the groove between the trachea and oesophagus, pass close to the inferior thyroid arteries behind the thyroid gland, and enter the larynx to supply all its intrinsic muscles except cricothyroid. The superior laryngeal nerve leaves the vagus high in the neck: its internal branch is sensory above the vocal folds and its external branch supplies cricothyroid.Right vagusInternal laryngeal n.External laryngeal n. → cricothyroidCommon carotid arteryInferior thyroid arteryRight subclavian arteryRight RLN (under subclavian)Tracheoesophageal grooveLarynx (thyroid cartilage)Thyroid glandTracheaLeft vagusLeft RLN (under the arch)Ligamentum arteriosumAortic archPulmonary trunkPatient's right ←→ Patient's leftDashed = behind the thyroid

Swipe sideways to see the whole diagram →

Course of the recurrent laryngeal nerves. Anterior view, patient's right on your left. The right RLN hooks under the right subclavian artery in the root of the neck; the left hooks under the aortic arch beside the ligamentum arteriosum, so it is longer and runs in the chest. Both climb in the tracheoesophageal groove past the inferior thyroid arteries to supply every intrinsic laryngeal muscle except cricothyroid (external laryngeal nerve). Hoarseness after thyroidectomy, or from a lung cancer or aortic aneurysm on the left, points to the RLN.
Original schematic, created for this atlas.
The glossopharyngeal, vagus and accessory nerves descending from the skull base in the neck, with the vagus continuing through the thorax to the stomach
The vagus descending through the neck and thorax to the stomach.
Henry Vandyke Carter, Gray's Anatomy of the Human Body, 20th ed. (1918), Fig. 793. Source · Public domain (Public domain in the US: published before January 1, 1931 (per Wikimedia Commons))

Clinical correlations

Vagus nerve lesion PANCE

Mechanism / lesion

Jugular foramen tumors, lateral medullary (Wallenberg) stroke, skull-base surgery, carotid dissection; distal lesions affect only the recurrent laryngeal branch.

Classic presentation

Uvula deviates away from the lesion (the intact side pulls it), the ipsilateral palate fails to elevate, hoarseness (cord paralysis), dysphagia, nasal regurgitation, reduced cough and gag (efferent).

Vasovagal (reflex) syncope and vagal maneuvers PANCE

Mechanism / lesion

Excess vagal outflow (with sympathetic withdrawal) → bradycardia and vasodilation; vagal maneuvers slow AV nodal conduction.

Classic presentation

Vasovagal syncope — prodrome (warmth, nausea, pallor) after pain, fear or prolonged standing, rapid recovery. Valsalva or carotid sinus massage can terminate AV-nodal re-entrant SVT.

Vagal effects in the gut

Mechanism / lesion

Vagal stimulation increases gastric acid and motility; vagotomy (historical ulcer surgery) and vagal injury during fundoplication or esophagectomy impair gastric emptying.

Classic presentation

Gastroparesis, diarrhea (dumping) after vagal injury; vagus nerve stimulation is used for refractory epilepsy and depression.

High-yield PANCE pearls

  • Uvula deviates away from a CN X lesion (toward the normal side).
  • Hoarseness + dysphagia + absent gag + ipsilateral Horner + crossed sensory loss → Wallenberg (lateral medulla).
  • Gag reflex efferent = CN X.
  • Vagal maneuvers (Valsalva, carotid massage) → first step for stable SVT.
  • Vagal trunks pass through the esophageal hiatus at T10.

Imaging anatomy

CT

Contrast CT of the neck and chest along the course of the vagus and recurrent laryngeal nerve (skull base to aortopulmonary window) for unexplained vocal cord paralysis.

MRI

MRI brainstem and skull base for medullary strokes and jugular foramen lesions.

Physical exam

Strength / function testing

Ask the patient to say "ah": watch the soft palate rise symmetrically and the uvula stay midline. Gag reflex (efferent limb), voice quality (hoarseness, nasal speech), cough strength, swallowing (water swallow test for aspiration risk).

Self-quiz

Q1.

When a patient says "ah," the uvula deviates to the right and the left soft palate does not elevate. Which nerve is affected?

Show answer

B

With a left vagus lesion, the intact right palatal muscles pull the uvula toward the right — the uvula deviates away from the side of the lesion.

Q2.

A hemodynamically stable 25-year-old has a narrow-complex regular tachycardia at 190/min. What is the first step?

Show answer

B

For stable SVT, start with vagal maneuvers (increase vagal tone at the AV node); if unsuccessful, give adenosine. Unstable patients need synchronized cardioversion.

Q3.

Which nerve carries the efferent limb of the gag reflex?

Show answer

B

The gag reflex has its afferent limb in CN IX and its efferent limb in CN X (pharyngeal and palatal muscles).

Q4.

How far along the gut does vagal parasympathetic supply extend?

Show answer

E

The vagus supplies the foregut and midgut, to about the distal third of the transverse colon. Beyond that, the pelvic splanchnic nerves (S2–S4) take over.

Q5.

Which pharyngeal muscle is NOT supplied by the vagus nerve?

Show answer

A

Stylopharyngeus is supplied by CN IX. The vagus supplies the other pharyngeal muscles and the soft palate except tensor veli palatini (V3).

Flashcards

See also