VAGUS NERVE AND ITS DESORDERS AND TREATMENT

2.  Is the tenth cranial nerve or CN X
 Interfaces with parasympathetic control of the heart, lungs
and digestive tract
 It is the longest nerve of the autonomic nervous system in
the human body.
 vagus nerve has two ganglia
1.Superior ganglion - round and lies in the jugular foramen
2.inferior ganglion - cylindrical and lies near the base of skull

4.  vagus nerve includes axons which emerge from or converge onto four
nuclei of the medulla:
The dorsal nucleus of vagus nerve — which sends parasympathetic
output to the viscera, especially the intestines
The nucleus ambiguus — which gives rise to the branchial efferent motor
fibers of the vagus nerve and preganglionic parasympathetic neurons that
innervate the heart
The solitary nucleus — which receives afferent taste information and
primary afferents from visceral organs
The spinal trigeminal nucleus — which receives information about
deep/crude touch, pain, and temperature of the outer ear, the dura of the
posterior cranial fossa and the mucosa of the larynx

6.  vagus nerve leaving the medulla oblongata between the pyramid and the
inferior cerebellar peduncle, the vagus nerve extends through the jugular
foramen, then passes into the carotid sheath between the internal carotid
artery and the internal jugular vein down to the neck, chest and abdomen,
where it contributes to the innervation of the viscera. Besides giving some
output to various organs, the vagus nerve comprises between 80% and 90% of
afferent nerves mostly conveying sensory information about the state of the
body's organs to the central nervous system
 The vagus nerves are paired(right/left)
1. right vagus nerve gives rise to the right recurrent laryngeal nerve, which
hooks around the right subclavian artery and ascends into the neck between
the trachea and esophagus. The right vagus then crosses anterior to the right
subclavian artery, runs posterior to the superior vena cava, descends
posterior to the right main bronchus, and contributes to cardiac, pulmonary,
and esophageal plexuses. It forms the posterior vagal trunk at the lower part
of the esophagus and enters the diaphragm through the esophageal hiatus.

7. 2. The left vagus nerve enters the thorax between left common carotid artery and left
subclavian artery and descends on the aortic arch. It gives rise to the left recurrent
laryngeal nerve, which hooks around the aortic arch to the left of the ligamentum
arteriosum and ascends between the trachea and esophagus. The left vagus further
gives off thoracic cardiac branches, breaks up into the pulmonary plexus, continues into
the esophageal plexus, and enters the abdomen as the anterior vagal trunk in the
esophageal hiatus of the diaphragm.
 Pharyngeal nerve
 Superior laryngeal nerve
 Superior cervical cardiac branches of vagus nerve
 Inferior cervical cardiac branch
 Recurrent laryngeal nerve
 Thoracic cardiac branches
 Branches to the pulmonary plexus
 Branches to the esophageal plexus
 Anterior vagal trunk
 Posterior vagal trunk
 Hering-Breuer reflex in alveoli

9. The vagus nerve supplies motor parasympathetic fibres to all the organs
except the suprarenal (adrenal) glands, from the neck down to the second
segment of the transverse colon. The vagus also controls a few skeletal
muscles such as
 Cricothyroid muscle
 Levator veli palatini muscle
 Salpingopharyngeus muscle
 Palatoglossus muscle
 Palatopharyngeus muscle
 Superior, middle and inferior pharyngeal constrictors
 Muscles of the larynx (speech)

10.  vagus nerve is responsible for such varied tasks as heart rate,
gastrointestinal peristalsis, sweating, and quite a few muscle movements in
the mouth, including speech (via the recurrent laryngeal nerve).
 It also has some afferent fibers that innervate the inner (canal) portion of
the outer ear (via the auricular branch, also known as Alderman's nerve) and
part of the meninges
 (This is the reason why a person may cough when tickled on the ear, such as
when trying to remove ear wax with a cotton swab)
Efferent vagus nerve fibres innervating the pharynx and back of the throat are
responsible for the gag reflex. In addition, 5-HT3 receptor-mediated afferent
vagus stimulation in the gut due to gastroenteritis and other insults is a cause
of vomiting

11. • General visceral efferent (GVE) — provides parasympathetic innervation to
glands of mucous membranes of the pharynx, larynx, organs in the neck,
thorax, and abdomen.
• Special visceral efferent (SVE) — innervates skeletal muscles of the pharynx
and larynx.
• General somatic afferent (GSA) — carries sensation from the external auditory
meatus and tympanic membrane.
• General visceral afferent (GVA) — carries information from the thoracic and
abdominal viscera; aortic body and arch.
• Special visceral afferent (SVA) — carries taste of the epiglottis region of the
tongue.

12. Parasympathetic innervation of the heart is partially controlled by the vagus
nerve and is shared by the thoracic ganglia
 vagal and spinal ganglionic nerves mediate the lowering of the heart rate.
right vagus branch innervates the sinoatrial node.
Parasympathetic tone from these sources are obviously well matched to
sympathetic tone in healthy people
Hyperstimulation of parasympathetic influence promotes bradyarrhythmias
hyperstimulated, the left vagal branch predisposes the heart to conduction
block at the atrioventricular node.

13.  Activation of the vagus nerve typically leads to a reduction in heart rate,
blood pressure, or both. This occurs commonly in the setting of
gastrointestinal illness such as viral gastroenteritis or acute cholecystitis, or
in response to other stimuli, including carotid sinus massage, Valsalva
maneuver or pain from any cause, in particular, having blood drawn.
 Activation of the vagus nerve typically leads to a reduction in heart rate,
blood pressure, or both. This occurs commonly in the setting of
gastrointestinal illness such as viral gastroenteritis or acute cholecystitis, or
in response to other stimuli, including carotid sinus massage, Valsalva
maneuver or pain from any cause, in particular, having blood drawn.
 Symptoms of irritable Bowel Syndrome are thought to cause activation of
the vagus nerve with many people reporting fainting, vision disturbances
and dizziness

14. Excessive activation of the vagal nerve during emotional stress, which is a
parasympathetic overcompensation of a strong sympathetic nervous system
response associated with stress, can also cause vasovagal syncope due to a
sudden drop in cardiac output, causing cerebral hypoperfusion. Vasovagal
syncope affects young children and women more than other groups. It can
also lead to temporary loss of bladder control under moments of extreme
fear
1. Pain - most common nerve pain symptoms are due to pinched nerve (when
nerve exits through tiny foramina in the skull).
2. Organ Dysfunction - a branch or tributary of nerve is affected that leads to
localized symptoms of organ dysfunction due to damage to nerve fibers or
discrepancy in the synthesis of neurotransmitters.

15. 3. Muscle Cramps - painfull and involuntary muscular contraction
4. Difficulty in Swallowing - Glottis is normally closed when a person is
swallowing in order to prevent the aspiration of food. This is managed by gag -
reflex (gagging sensation if the back of throat is touched). In patients of head
injury or stroke, gag reflex may get impaired leading to choking while eating and
difficulty in swallowing.
5. Peptic Ulcer - Defects in the normal functioning of Vagus nerve may impair
the normal control mechanisms that modulate the gastric acid secretion.
Excessive secretion of peptic acid can lead to ulceration, dyspepsia and gastro-
esophageal reflux disease.
6. Gastroparesis - under-activity of vagus nerve may interfere with the blood
supply of stomach after ingestion of food that leads to improper digestion.
Gastroparesis is marked by painful spasms in the stomach that affect normal
food intake, heartburn, nausea and weight loss.

16. 7. Fainting - Over-activity of Vagus nerve increases the firing rate of receptors that
presents with sudden episodes of collapse and fainting (also referred to as vasovagal
reflex). Although, it is not dangerous, but fainting episodes may increase the risk of
accidental injuries that may prove life threatening.
8. Other Symptoms - Other symptoms include changes in the rhythm of heart, urinary
difficulties and changes in vocal tone.
 Nerves are protected by myelin sheaths that serve to prevent the delicate nerve fibers
from damage and destruction; however, aberrations in normal biochemical
environment due to excessive alcoholism or persistently raised blood sugar levels can
lead to swelling of myelin sheaths that lead to permanent destruction of nerve fibers
leading to inactivity of nerves. Other causes includes inflammatory disorders,
autoimmune destruction of nerves (in the setting of diseases like amyotrophic lateral
sclerosis, multiple sclerosis and other), viral infections and damage due to neoplastic
conditions that press upon nerves causing mechanical damage.

17.  Ask person to swallow
 Ask person to say ah-h-h to check movement of the plate uvula
 Back of the throat may be touched with a tounge blade which evokes the gag
reflexin most peoples
 Person is asked to speak to determine whether the voice sounds nasal (for
palate movement)

18. 1. Vagus Nerve Stimulation - Vagal nerve stimulation can be achieved by
a device (similar in activity to cardiac pacemaker) that is implanted
beneath the skin and helps in generating impulses that can help in
managing symptoms of depression and seizures.
2. Neck Extension Exercises - Often times, pressure in the tendons or
tense muscles can press upon vagus nerve that may lead to hyper or
hypoactivity of nerves. 3- Dimensional exercises like neck extension
(moving your chin away from chest as far as possible), neck flexion
(touching your chin with your chest) and neck retraction exercises can
help in decreasing pressure on nerve.

19. 3. Yoga
4. For Gastroparesis - In order to manage symptoms of Gastroparesis and reduce
the risk of severe malnutrition, healthcare providers suggest the use of feeding
tube that supply the nutrients directly to intestines without crossing stomach. In
order to reduce the symptoms of nausea and vomiting, medications like
ondansetron can be employed. Metoclopramide is usually reserved for severe
cases
5. For Fainting - Different medications are employed to manage the fainting
episodes (that mostly involve controlling vasovagal discharge). Sertraline or
paroxetine are currently the treatment of choice for such cases.