Vagus nerve !
The vagus nerve is a long cranial nerve running down the neck beside the carotid artery; it carries signals to the voice box, heart, lungs and gut.
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What it is
A long cranial nerve running down the neck inside the carotid sheath, beside the carotid artery and jugular vein.
What it does
Carries signals to the voice box, heart, lungs and gut.
Key facts
- Roots
- CN X from the medulla oblongata; exits the jugular foramen; descends in the carotid sheath between internal jugular vein and carotid artery
- Moves
- Pharynx, larynx, soft palate (except tensor veli palatini); parasympathetic to heart, lungs and gut up to the left colic flexure; branches: pharyngeal (pharyngeal plexus), superior laryngeal, recurrent laryngeal, cardiac, pulmonary, oesophageal, anterior and posterior vagal trunks (gastric, hepatic, celiac)
- Feeling from
- Larynx, pharynx, external acoustic meatus (auricular branch), thoracic and abdominal viscera; taste from epiglottis; meningeal branch (posterior fossa dura); carotid body branch
Relations
- Course
- Leaves the jugular foramen with CN IX and XI, descends in the carotid sheath, crosses in front of the subclavian artery (right) or the aortic arch (left), passes behind the lung root to the oesophageal plexus and enters the abdomen as anterior (mainly left) and posterior (mainly right) vagal trunks
- Lateral
- The internal jugular vein in the carotid sheath
- Medial
- The internal and common carotid arteries, then the pharynx and larynx; in the chest the trachea and oesophagus
- Behind
- The sympathetic trunk and prevertebral muscles behind the carotid sheath
How to find it
It cannot be felt. On neck ultrasound it is a small round structure behind and between the carotid artery and internal jugular vein. In thyroid surgery the recurrent laryngeal nerve is found in the groove between trachea and oesophagus, near the inferior thyroid artery.
Examination
- Saying 'ah': the palate rises unevenly and the uvula moves away from the weak side
- Gag reflex: sensory limb glossopharyngeal, motor limb vagus; reduced on the side of a vagus lesion
- Laryngoscopy shows a vocal cord fixed near the midline or further out after recurrent laryngeal nerve injury
- Voice and cough: a breathy voice and a weak, 'bovine' cough suggest a paralysed vocal cord
On imaging
In the neck ultrasound shows it inside the carotid sheath, usually behind and between the common carotid artery and the internal jugular vein. In vocal cord palsy, CT covers the whole course of the nerve and its recurrent branch, from skull base to the aortopulmonary window, where a lung or nodal mass often explains a left palsy. A vagal schwannoma or paraganglioma is a carotid space mass on MRI.
Clinical notes
- Hoarseness after thyroid or parathyroid surgery: recurrent laryngeal nerve injury near the inferior thyroid artery; injury to the external branch of the superior laryngeal nerve (near the superior thyroid artery) lowers pitch and vocal power
- Left recurrent nerve palsy from chest disease: lung cancer in the aortopulmonary window, aortic arch aneurysm, a very large left atrium (Ortner syndrome), and after cardiac or aortic surgery
- Carotid endarterectomy and neck trauma can injure the vagus itself in the carotid sheath
- Vasovagal syncope: a reflex surge of vagal activity slows the heart while vessels dilate, so blood pressure drops and the person faints
Anatomical variants
- Non-recurrent right laryngeal nerve (under 1%), going straight from the vagus to the larynx when the right subclavian artery arises abnormally from the arch; a hazard in thyroid surgery
Development
The vagus is the nerve of the fourth and sixth pharyngeal arches. On the right the sixth arch artery fades and the nerve hooks under the subclavian artery; on the left the ductus arteriosus persists and holds it under the arch.
Memory aid
"LARP": Left vagus becomes the Anterior trunk, Right the Posterior, as they pass through the diaphragm.
Related conditions
Test yourself
Think of the answer, then tap the question to see it.
Through which foramen does the vagus nerve leave the skull, and where does it lie in the carotid sheath?
The jugular foramen; in the carotid sheath it lies between and behind the internal jugular vein and the carotid artery.
Around which structures do the right and left recurrent laryngeal nerves hook?
Right: the right subclavian artery. Left: the aortic arch beside the ligamentum arteriosum, so the left is longer and more often damaged by chest disease.
Which intrinsic laryngeal muscle is not supplied by the recurrent laryngeal nerve?
Cricothyroid, supplied by the external branch of the superior laryngeal nerve.
With a high vagus nerve lesion, which way does the uvula deviate on saying «ah»?
Toward the healthy side, because the palate sags on the side of the lesion.
What does a damaged recurrent laryngeal nerve cause?
Hoarseness with a one-sided injury; injury on both sides can block the airway.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- nervus vagus TA2 6332
- Official Spanish (DeCS)
- Nervio vago DeCS D014630
- English (TA2)
- Vagus nerve
- Also called
- cranial nerve X · for the Anterior and Posterior vagal trunks · see Divisio autonomica
Related
Sources: Terminologia Anatomica (TA2); DeCS; Neuroanatomy, Cranial Nerve 10 (Vagus Nerve).
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Representative model, for educational purposes only.
