VAGUS NERVE
DR ADARSH I NATH
SENIOR RESIDENT
DEPT OF NEUROSURGERY
GOVT MEDICAL COLLEGE, KOZHIKODE

• INTRODUCTION
• ORIGIN
• COURSE & RELATIONS
• ACTIONS
• EXAMINATION
• LOCALISATION

• INTRODUCTION
• ORIGIN
• COURSE & RELATIONS
• ACTIONS
• EXAMINATION
• LOCALISATION

INTRODUCTION
• The Longest and most widely distributed Cranial Nerve
• Same nuclei of origin as for 9th cranial nerve.
• Both Motor and Sensory segments
• One of the Parasympathetic cranial nerve
• Despite its clinical importance , it is difficult to evaluate bedside.

• General Somatic Afferent – Touch, Pain & Temperature – Spinal nucleus of Vth
• Special Visceral Afferent - Taste buds of the Epiglottis – Nucleus Tractus
Solitarius
• Special Visceral Efferent- Motor/ Brachiomotor – Nucleus Ambigious
• General Visceral Afferent – Dorsal nucleus of Vagus
• General Visceral Efferent - Secretomotor fibres – Dorsal nucleus of Vagus

• INTRODUCTION
• ORIGIN
• COURSE & RELATIONS
• ACTIONS
• EXAMINATION
• LOCALISATION

• INTRODUCTION
• ORIGIN
• COURSE & RELATIONS
• ACTIONS
• EXAMINATION
• LOCALISATION

EXIT OF THE NERVE FROM BRAINSTEM

RELATION TO PICA

RELATION TO PICA

COURSE
• The six to eight rootlets of the vagus nerve emerge from the posterior sulcus of
the lateral medulla oblongata dorsal to the inferior olive in close association with
the glossopharyngeal nerve.
• These vagal rootlets form a single trunk that leaves the skull by way of the jugular
foramen in a dural sheath that also contains the spinal accessory nerve

JUGULAR FORAMEN
• Cavity formed by the petrous part of the temporal bone (A) and occipital bone (P)
• It lies lateral to the occipital condyles, Medial to it lies the Hypoglossal canal
• Foramen is divided by a fibro-ossesous bridge that connects the jugular spine on
the petrous part of the temporal bone and jugular process of the occipital bone,
into 2 parts
• Antero- Medial – Pars Nervosa (9th,Jacobsens nerve, Inferior petrosal sinus)
• -- Pars Vascularis ( Jugular Bulb, Xth ,Arnolds nerve, X1th )

GENERAL SENSORY AFFERENT
• The auricular ramus (nerve of Arnold) of the Vagus nerve is given off; this branch
then traverses the mastoid process and innervates the skin of the concha of the
external ear, External acoustic meatus, tympanic cavity
• At this point the Vagus also gives off the meningeal ramus, which runs to the
dura mater of the posterior fossa

SPECIAL VISCERAL AFFERENT
• Within the nodose ganglion are cells whose fibers carry taste sensation from the
epiglottis, hard and soft palates, and pharynx.
• The axons of these ganglion cells terminate in the nucleus solitarius of the
medulla.

SPECIAL VISCERAL EFFERENT
• Pharyngeal ramus, which forms the pharyngeal plexus with the glossopharyngeal
nerve and sends motor fibers to the muscles of the pharynx and the soft palate
(except the stylopharyngeus and tensor veli palatini muscles).
• The superior laryngeal nerve arises from the vagus near the nodose ganglion and
divides into a predominantly motor external ramus (to the cricothyroid muscle)
and an internal ramus (which pierces the thyrohyoid membrane and sends
sensory fibers to the larynx).

• In the neck, the vagus nerve proper descends within a sheath common to the
internal carotid artery and the internal jugular vein.
• Within the neck, the vagus gives off the cardiac rami, which follow the carotid
arteries down to the aorta and contribute fibers to the cardiac plexus.
• At the root of the neck, the recurrent laryngeal nerves are given off and pursue
different courses on the two sides.
• The right recurrent laryngeal nerve bends upward behind the subclavian artery to
ascend in the tracheoesophageal sulcus, whereas the left recurrent laryngeal
nerve passes beneath the aortic arch to attain this sulcus

THE RECURRENT LARYNGEAL NERVE

INTO THE THORAX
• The vagus nerve enters the thorax, crossing over the subclavian artery on the
right side and traveling between the left common carotid and subclavian arteries
on the left side.
• The right nerve then passes downward near the brachiocephalic trunk and
trachea and behind the right brachiocephalic vein and superior vena cava to the
posterior lung root
• The left nerve travels between the left common carotid and subclavian artery,
passes over the aortic arch, and reaches the left lung root.

GENERAL VISCERAL EFFERENT
• Bronchial branches ( Pulmonary Plexus) – Anterior & Posterior
• Superior, Anterior & Thoracic Cardiac branches – Cardiac plexus- Intramural
Ganglion
• Esophageal Plexus – Then divides into Anterior & Posterior Gastric Nerves

INTO THE ABDOMINAL VISCERA
• Right Vagus – Celiac plexus – Adrenals, Kidney, Intestine, Pancreas & Spleen
• Left Vagus- Hepatic Plexus – Liver & Gall Bladder.

GENERAL VISCERAL AFFERENT
• General visceral sensations from the oropharynx, larynx, and linings of the
thoracic and abdominal viscera have their cells of origin in the nodose ganglion,
which also projects to the nucleus solitaries (nucleus parasolitarius).
• These include sensations from Esophageal, Celiac, Hepatic Plexus
• Internal Laryngeal nerve – Above the vocal cord
• Recurrent laryngeal nerve- Below the vocal cord
• Aortic arches & Carotid bodies.

• INTRODUCTION
• ORIGIN
• COURSE & RELATIONS
• ACTIONS
• EXAMINATION
• LOCALISATION

ACTIONS OF XTH NERVE
• Swallowing
• Phonation
• Airway Protection
• Modulation

• INTRODUCTION
• ORIGIN
• COURSE & RELATIONS
• ACTIONS
• EXAMINATION
• LOCALISATION

EXAMINATION OF VAGUS
• MOTOR FUNCTIONS
• AUTONOMIC FUNCTIONS
• SENSORY FUNCTIONS
• REFLEXES
• DISORDERS OF THE FUNCTION

EXAMINATION OF MOTOR FUNCTIONS.
• 1) Character of voice & Ability to swallow- Branchiomotor function assessment
• 2) Soft Palate – Palate & Uvula.
• 3) Examination of Pharynx.
• 4) Assessment of Vocal Cords.

DISORDERS OF FUNCTION OF MOTOR PART
• Voice & Swallowing
• Acute Unilateral lesions – Nasal Quality & Dysphagia, marked for liquids –
Velopharyngeal insufficiency

• Soft Palate
• Unilateral weakness – Levator veli palatini and musculus uvulae, which causes
droop of the palate and flattening of the palatal arch.
• The preserved function of tensor veli palatini – prevent marked drooping of
palate.
• The palatal gag reflex may be lost on the involved side due to interruption of
motor pathway

• Pharynx.
• Unilateral weakness of superior constrictor – “Curtain movements” with motion
the pharyngeal wall towards the non paralyzed side.
• Normal elevation of larynx may be absent on one side in U/L lesions on both
sides in B/L lesions.

• Vocal Cord Assessment
• A unilateral lesion of the Vagus may cause cord weakness or paralysis.
• Vocal cord dysfunction alters the character and quality of the voice and may
produce abnormalities of articulation, difficulty with respiration, and impairment
of coughing.
• Spasmodic dysphonia is a common focal dystonia that involves the vocal cords
and causes characteristic voice changes

EXAMINATION OF AUTONOMIC FUNCTIONS
• Orthostatic hypotension
• Abnormalities of sweating
• Dysfunction of the GI/ Genitourinary

ORTHOSTATIC CHANGES
• Changes in BP- Supine to Standing- Fall in SBP up to 30 & DBP up to 15
• Changes in HR- The fall in BP produces reflex Tachycardia
• Testing – Variability to deep breathing, standing & Performing Valsalva.

SENSORY FUNCTION
• Sensory function of the vagus nerve cannot be tested adequately because the
area of supply overlaps that of other cranial nerves (e.g., the pinna),
• Some structures are inaccessible (e.g., the meninges), and there is difficulty in
testing the epiglottis for taste function

REFLEX FUNCTION
• The afferent limb of the pharyngeal reflex (gag reflex) runs in the
glossopharyngeal nerve, and the efferent limb runs in the glossopharyngeal and
Vagus nerves.
• Therefore, unilateral vagal lesions depress the ipsilateral gag reflex by interrupting
the efferent arc
• Occulocardiac reflex ( Aschner Ocular Phenomenon)
• Carotid Sinus reflex.- Bradycardia, Hypotension, Vasodilatation.
• Vomiting reflex, Swallowing reflex & Hiccups.

• INTRODUCTION
• ORIGIN
• COURSE & RELATIONS
• ACTIONS
• EXAMINATION
• LOCALISATION

LOCALIZATION OF VAGUS NERVE PATHOLOGIES
• Supranuclear lesion
• Nuclear lesions and lesions within the brainstem
• Lesions within the posterior fossa.
• Lesions affecting the vagus nerve proper
• Lesions of the superior laryngeal nerve
• Lesions of the recurrent laryngeal nerve.

SUPRANUCLEAR LESION
• Unilateral cerebral hemispheric lesions (lower precentral gyrus) rarely cause any
vagal dysfunction because the supranuclear control is bilateral.
• Rarely, dysphagia may occur with a unilateral precentral lesion
• . Bilateral upper motor neuron lesions result in pseudo-bulbar palsy, in which
dysphagia and spastic dysarthria are prominent. Emotional incontinence with
pathologic crying is common.
• The gag reflex may be depressed or exaggerated.

NUCLEAR LESIONS AND LESIONS WITHIN THE
BRAINSTEM
• Nuclear lesions result in ipsilateral palatal, pharyngeal, and laryngeal paralysis that
is usually associated with affection of other cranial nerve nuclei, roots, and long
tracts.
• Lesions of the nucleus ambiguus may occur with vascular insults (lateral
medullary or Wallenberg syndrome), tumors, syringobulbia, motor neuron
disease, and inflammatory disease

LESIONS WITHIN THE POSTERIOR FOSSA
• Lesions at this location usually also involve the glossopharyngeal, spinal
accessory, and hypoglossal nerves
• Include primary (e.g., paragangliomas ) and metastatic tumors, infections (e.g.,
meningitis, otitis), carcinomatous meningitis, sarcoidosis, Guillain–Barré
syndrome, and trauma

LESIONS AFFECTING THE VAGUS NERVE PROPER
• The trunk of the Vagus nerve may be injured in the neck and thorax by tumors,
aneurysms of the internal carotid artery, trauma, and enlarged lymph nodes.
• These injuries result in complete ipsilateral vocal cord paralysis associated with
unilateral laryngeal anesthesia
• Other causes include : Neurosyphilis, Radiation Therapy, Sarcoidosis, reactivation
of herpes simplex type 1 infection, and diabetes.

LESIONS OF THE SUPERIOR LARYNGEAL NERVE
• Lesions of this nerve result in few clinical findings because this branch is primarily
sensory.
• The cricothyroid muscle is innervated by this branch, however, and its
involvement may result in mild hoarseness with some decrease in voice strength

LESIONS OF THE RECURRENT LARYNGEAL NERVE
• The recurrent laryngeal nerve is susceptible to injury throughout its intrathoracic
course by aneurysms of the aortic arch or subclavian artery, enlarged
tracheobronchial lymph nodes, mediastinal tumors, and operative damage (e.g.,
thyroidectomy).
• Unilateral recurrent laryngeal nerve injury results in hoarseness that is often
transient
• Bilateral abduction paralysis may produce severe approximation of the vocal cords
associated with airway limitation, which often necessitates tracheostomy.
Inspiratory stridor and dyspnea on exertion are common.
• Acute vocal cord paralysis may occur in patients with hereditary neuropathy with
liability to pressure palsies

VAGAL NERVE STIMULATION

REFERENCES
• Dejong’s , The Neurologic Examination , Seventh Edition
• Rhotons Anatomy.
• Paul Brazis – Localization in clinical Neurology
• Uptodate.com