VAGUS (CN X) NERVES
DR. SUMIT KAMBLE
DEPT. OF NEUROLOGY
• Distributed principally to tongue and pharynx.
• Conveys general sensory as well as special sensory (taste) fibers
from posterior third of the tongue.
• Provides general sensory innervation to pharynx, area of the
tonsil, internal surface of the tympanic membrane, and skin of
the external ear.
• Conveys GVAs from the carotid body and carotid sinus.
• Its skeletomotor neurons innervate the stylopharyngeus muscle,
and its parasympathetic component innervates the parotid gland.
• Both motor and sensory
• Motor - Stylopharyngeus
• Parasympathetic secretomotor - Parotid gland
• Sensory: tympanic cavity, Eustachian tube, fauces, tonsils,
nasopharynx, uvula, inferior surface of the soft palate and
posterior (postsulcal) third of the tongue.
• Motor Nucleus - rostral part of the nucleus ambiguus, it is
situated deep in the reticular formation medial to the spinal tract
and nucleus of trigeminal nerve.
• Supplies- stylopharyngeus.
• Sensory neurons - located in superior and inferior
• GVA - convey information from carotid body and carotid sinus,
as well as visceral sensation from the pharynx;
• SVA - convey taste sensation.
• GSA – convey exteroceptive sensation from the mucous
membranes of the tympanic cavity, mastoid air cells, and
auditory canal via the tympanic plexus and tympanic branch.
• Supplies parasympathetic innervation to parotid gland and to
mucous membranes of posterior inferior mouth and pharynx.
• Parasympathetic nuclei in lower brainstem are the superior and
inferior salivatory and the dorsal motor nucleus of CN X
• Motor paresis may be negligible
• Stylopharyngeal function difficult to assess.
• Mild dysphagia, lower palatal arch on same side.
• Loss of taste sensation over post. third of tongue on same side.
• Pain and touch over soft palate, post. third of the tongue,
tonsilar regions and pharyngeal wall over ipsilateral side.
• Pharyngeal or Gag reflex
• Palatal reflex
• Afferent – Glasopharyngeal
• Efferent- Glasopharyngeal and Vagus
• Salivary secretion from parotid may be decreased.
LOCALIZATION OF LESSIONS
• Unilateral – No deficit
• Bilateral- Pseudobulbar palsy
• Severe dysphagia, pseudo-bulbar signs ( pathological laughter
and crying, spastic tongue, spastic dysarthria) , exaggerated gag
NUCLEAR AND INTRAMEDULLARY
• Include Syringobulbia, demyelinating disease, vascular disease,
MND and Malignancy.
• Commonly involve other cranial nerve and other brainstem
1. Cerebellopontine angle syndrome –
• CP angle tumors especially acoustic tumors
• Associated with tinnitus, deafness and vertigo (CN VIII), facial
sensory abnormalities (cranial verve V) and cerebellar signs.
2. Jugular foramen syndrome (Vernet syndrome)
• Injure CN IX, X and XI, which travel through this foramen.
• Glomus jugulare tumors, neuroma, metastasis, cholesteatoma,
meningioma, infections and giant cell arteritis.
3. Lesions within Retropharyngeal and Retroparotid space
• May be injured by neoplasm ( nasopharyngeal carcinoma),
abscesses, adenopathy, aneurysm, trauma or surgical procedures
• Collet-Sicard syndrome ( CN IX, X, XI and XII)
• Villaret syndrome (CN IX, X, XI and XII, sympathetic chain
and occasionally CN VII).
• Attacks of severe lancinating pain originating in one side of the
throat or tonsillar region and radiating along the course of the
eustachian tube to the tympanic membrane, external auditory
canal, behind the angle of the jaw, and adjacent portion of the
• Trigger zones
• Pain lasting for seconds to minutes may be brought on by
talking, eating, swallowing, or coughing.
• It can lead to syncope, convulsions, and rarely to cardiac arrest
because of stimulation of the carotid sinus reflex.
• Inadvertent activation of the baroreceptors in the carotid sinus
causing bradycardia and hypotension.
• Identifiable etiologies may include constriction around the neck
(e.g., tight collar) or a mass in the neck impinging on the sinus,
but many cases are idiopathic.
• Longest and most widely distributed CN
• Vagus nerve is associated with the derivatives of the fourth
• Connects with four brainstem nuclei: nucleus ambiguus,
DMNX, nucleus of the spinal tract of CN V, and nucleus of the
• Sensory: GSA sensation from pharynx, larynx, ear, and
meninges and GVA from the larynx, viscera of the thorax and
abdomen, and receptors in the aorta.
• Special Sensory: Provides taste sensation to the epiglottis and
root of the tongue.
• Motor: Provides motor innervation to the majority of the
muscles of the pharynx, soft palate and larynx.
• Parasympathetic: Innervates the smooth muscle of the trachea,
bronchi and gastro-intestinal tract and regulates heart rhythm.
• Originates from the medulla and exits the cranium via jugular
foramen, with the glossopharyngeal and accessory nerves .
• Within the cranium, auricular branch arises. This supplies
sensation to the posterior part of the external auditory and canal
In the Neck
• Passes into the carotid sheath, travelling inferiorly with the
internal jugular vein and common carotid artery.
• At the base of neck, right and left nerves have differing
• Right vagus nerve passes anterior to the subclavian artery and
posterior to the sternoclavicular joint, entering the thorax.
• Left vagus nerve passes inferiorly between the left common
carotid and left subclavian arteries, posterior to the
sternoclavicular joint, entering the thorax.
Several branches arise in the neck:
• Pharyngeal branches – motor innervation to majority of the
muscles of the pharynx and soft palate.
• Superior laryngeal nerve – Splits into internal and external
• Recurrent laryngeal nerve - It innervates the majority of the
intrinsic muscles of the larynx.
In the Thorax
• Right vagus nerve forms posterior vagal trunk, and the left
forms anterior vagal trunk.
• Two other branches arise in the thorax:
• Left recurrent laryngeal nerve – innervate majority of the
intrinsic muscles of the larynx.
• Cardiac branches – regulate heart rate and provide visceral
sensation to the organ.
• Vagal trunks enter the abdomen via the oesophageal hiatus, an
opening in the diaphragm.
• In the Abdomen
• In the abdomen, the vagal trunks terminate by dividing into
branches that supply the oesophagus, stomach and the small and
large bowel (up to the splenic flexure).
Vagus has two sensory ganglia.
1. Superior (jugular) vagal ganglion located in the jugular fossa
of the temporal bone;
2. Inferior (nodose) ganglion is located just distal to the jugular
10 major terminal branches that arise at different levels:
• (a) meningeal, (b) auricular, (c) pharyngeal, (d) carotid, (e)
superior laryngeal, (f ) recurrent laryngeal, (g) cardiac, (h)
esophageal, (i) pulmonary, and (j) gastrointestinal.
• There are somatic and visceral components to the sensory
function of the vagus nerve.
• Superior ganglion primarily conveys somatic sensation,
• Inferior ganglion relays general visceral sensation and taste.
• Somatic sensory portion conveys pain, temperature, and touch
sensation from the pharynx, larynx, ear canal, external surface
of the tympanic membrane, and meninges of posterior fossa.
• General sensory fibers from the region of the ear, ear canal, and
tympanic membrane travel in the auricular branch (nerve of
• GSA fibers in CN X synapse in the nucleus of the spinal tract of
• In the larynx, GSA fibers from above the vocal folds travel in
the internal laryngeal branch of the superior laryngeal nerve;
• Fibers from below the vocal folds travel with the recurrent
• Viscera sensation (GVA) is that from the organs of the body.
• Central processes terminate in the caudal portion of the solitary
• The vagus nerve innervates:
• Laryngopharynx – via the internal laryngeal nerve.
• Superior aspect of larynx (above vocal folds) – via the internal
• Heart – via cardiac branches of the vagus nerve.
• Gastro-intestinal tract (up to the splenic flexure) – via the
terminal branches of the vagus nerve.
• Collaterals to reticular formation, DMNX, and other CN nuclei
mediate important visceral reflexes and are involved in the
regulation of cardiovascular, respiratory, and gastrointestinal
• Special visceral afferent (SVA )- Vagus nerve has a minor role
in taste sensation.
• It carries afferent fibres from the root of tongue and epiglottis.
• Vagus nerve innervates the majority of the muscles associated
with the pharynx and larynx.
• These muscles are responsible for the initiation of swallowing
Muscles of the Pharynx
• Most of the muscles of the pharynx are innervated
by pharyngeal branches of the vagus nerve:
1. Superior, middle and inferior pharyngeal constrictor muscles
• Muscles of the Larynx
• Innervation to the intrinsic muscles of the larynx is achieved
via recurrent laryngeal nerve and external branch of the
superior laryngeal nerve.
Recurrent laryngeal nerve:
• Posterior crico-arytenoid
• Lateral crico-arytenoid
• Transverse and oblique arytenoids
External laryngeal nerve:
• In addition to the pharynx and larynx, the vagus nerve also
innervates palatoglossus of the tongue, and the majority of the
muscles of the soft palate.
• Vagus nerve is main parasympathetic outflow to the heart and
• Parasympathetic component of CN X arises from the DMNX.
• Vagal discharge causes bradycardia, hypotension,
bronchoconstriction, bronchorrhea, increased peristalsis,
increased gastric secretion, and inhibition of adrenal function.
• Cardiac branches arise in the thorax, conveying parasympathetic
innervation to the sino-atrial and atrio-ventricular nodes of the
• Stimulate reduction in the resting heart rate. They are
constantly active, producing a rhythm of 60 – 80 beats per
• Sends branches to the oesophagus, stomach and most of the
intestinal tract – up to the splenic flexure of the large colon.
• Stimulate smooth muscle contraction and glandular secretions
in these organs.
1. Character of voice and ability to swallow-
• With acute unilateral lesions, speech may have a nasal quality
and dysphagia more marked for liquids than solids, with a
tendency to nasal regurgitation.
2. Examination of the soft palate
• Position of palate and uvula
• With a unilateral lesion -
weakness of the levator veli
palatini and musculus uvulae,
causes a droop of the palate and
flattening of the palatal arch
• Preserved function of the tensor
veli palatini may prevent marked
drooping of the palate.
• On phonation, median raphe
deviates toward the normal side.
3. Palatal gag reflex - may be lost on involved side because of
interruption of motor rather than sensory path.
4. Bilateral vagus involvement
• Palate cannot elevate on phonation; it may or may not droop,
depending on the function of the tensor veli palatini.
• Palatal gag reflex is absent bilaterally.
• Nasal speech and nasal regurgitation of liquids.
5. Vocal cord weakness - alters the character and quality of the
voice and may produce abnormalities of articulation, difficulty
with respiration, and impairment of coughing.
• Most common cause of vocal cord paralysis is a lesion of one
recurrent laryngeal nerve.
• Not clinically important and cannot be adequately tested.
• Unilateral vagal lesion depress the ipsilateral gag reflex by
interrupting the efferent arc.
LOCALIZATION OF LESIONS
• Unilateral – No deficit
• Bilateral- Pseudobulbar palsy
NUCLEAR LESIONS AND BRAINSTEM LESIONS
• Nuclear- result in ipsilateral palatal, pharyngeal and laryngeal
paralysis and usually associated with affection of other CN
nuclei, roots and long tracts.
• Causes- Vascular, tumors, syringobulbia, MND and
LESIONS WITHIN POSTERIOR FOSSA
• Lesion at this location usually also involve the CN IX, XI and
• Causes include primary (Glomus jugulare) and metastatic
tumors, infections, carcinomatous meningitis, sarcoidosis, GBS
SYNDROME CN involved
Jugular foramen syndrome of Vernet IX, X, XI
Schmidts syndrome X, XI
Hughlings Jackson syndrome X, XI, XII
Collet-Sicard syndrome IX,X, XI, XII
LESION AFFECTING VAGUS NERVE PROPER
• Trunk of vagus nerve may be injure in neck and thorax by
tumors, aneurysms of internal carotid artery, trauma and
enlarged lymph nodes.
• Result in complete ipsilateral vocal cord paralysis associated
with unilateral laryngeal anesthesia.
LESIONS OF SUPERIOR LARYNGEAL NERVE
• Damaged by trauma, surgery or tumor.
• Few clinical findings.
• Mild hoarseness due to paralysis of cricothyroid.
LESIONS OF RECURRENT LARYNGEAL NERVE
• May be damaged by tumors in neck, especially carcinoma of the
thyroid, cervical adenopathy, metastatic lesions, Hodgkin
disease, lymphosarcoma, aortic aneurysms, mitral stenosis with
enlargement of the left atrium, pericarditis, mediastinal and
apical tumors, stab wounds in the neck, or accidental trauma
during a thyroidectomy or other surgical procedure.
UNILATERAL- flaccid dysphonia with breathiness and mild
inspiratory stridor; Diplophonia may occur.
• On laryngoscopy paralyzed vocal cord lies near midline.
BILATERAL -cause abduction impairment and leave the vocal
cords approximating each other in the midline.
• Results in dyspnea and inspiratory stridor.
• Can be seen after thyroidectomy, polyneuropathy or carcinoma
of thyroid or esophagus.