anatomy of vagus nerve ,about course of vagus nerve and its branches

1. ANATOMY OF VAGUS NERVE

2. INTRODUCTION
VAGUS NERVE
• So called due to its vague course
through the head, neck, thorax
and the abdomen.
• Longest nerve of the autonomic
nervous system in the body
• MIXED NERVE: sensory, motor
and parasympathetic

3. Primarily associated with the parasympathetic
division of the autonomic nervous system, however,
it also has some sympathetic influence through
peripheral chemoreceptors.
Associated with the derivatives of the fourth
pharyngeal arch.
SURFACE MARKING:
Runs along the posteromedial side of Internal
Jugular Vein
Marked by 2 points :
1. Antero-inferior part of tragus
2. Medial end of the clavicle

4. NUCLEI
Within the medulla oblongata of the
brainstem, there are 4 vagal nuclei,
onto which axons of the vagus nerve
emerge from or converge onto:
1. NUCLEUS AMBIGUOUS
(BRANCHIOMOTOR): (SVE)
2. DORSAL MOTOR NUCLEUS
(PARASYMAPATHETIC) (GVE)
3. NUCLEUS OF TRACTUS SOLITARIS
(GUSTATORY)(SVA,GVA)
4. NUCLEUS OF SPINAL TRACT OF
TRIGEMINAL(GSA)

5. Functional Components
• 1. Special visceral efferent fibres: supply the muscles of palate, pharynx, and larynx.
They arise from nucleus ambiguus
• 2. General visceral efferent fibres: arise from the dorsal nucleus of vagus, and provide
parasympathetic innervation to heart, bronchial tree, and most of the GIT.
• 3. Special visceral afferent fibres: carry taste sensations from the posteriormost part of
the tongue and epiglottis and terminate in the nucleus tractus solitarius.
• 4. General visceral afferent fibres:carry general sensations from the mucous membrane
of pharynx, larynx, trachea,esophagus, and thoracic and abdominal viscera and
terminate in the nucleus tractus solitarius and some in the dorsal nucleus of the vagus.
• 5. General somatic afferent fibres: carry general sensations from skin of the auricle and
terminate in the nucleus of the spinal tract of the trigeminal nerve.

6. GANGLIA ASSOCIATED
1 superior ganglia
2 inferior /Ganglion nodasum
SUPERIOR/JUGULAR
• Lies within the Juglar Foramen
• Rounded
• Smaller in size
• Connected to IX, XI and to Superior
Cervical Ganglion .
1.MENINGEAL
2.AURICULAR

7. INFERIOR/GANGLION NODASUM
Below the Juglar Foramen Near the skull
base
• Cylindrical (2.5 cm)
• Larger
• Joined by cranial root of XI;related to
XII, superior cervical ganglion
1.PHARYNGEAL
2.CAROTID
3.SUPERIOR LARYNGEAL
4.RECURRENT LARYNGEAL
5.CARDIAC

8. COURSE (INTRACRANIAL & EXTRACRANIAL )
INTRACRANIAL
• from Lateral aspect of medulla Nerve
attached to 10 rootlets ,Posterolateral
sulcus of medulla Rootlets unite –
Single trunk
• Laterally crosses the jugular tubercle
along with IX, XI
• Leaves the cranial cavity by passing
through the middle part of jugular
foramen
• In the foramen, joined by the cranial
root of the accessory nerve.

9. EXTRACRANIAL:
In neck
Descends within the carotid
sheath(b/w IJV laterally and ICA
medially) to the root of neck
Right Vagus in front of Right
Subclavian Artery Left Vagus
between left common carotid and
left subclavian arteries Enter the
Thorax via Root of the neck

10. In thorax
• passes behind respective lung roots
• Rt vagus behind oesophagus(posterior vagal
trunk)
• Lt vagus in front of oesophagus (anterior
vagal trunk)
• crosses diaphragm via oesophageal opening
In abdomen
vagal trunk divided into terminal branches

11. BRANCHES
SUPERIOR GANGLIA
1.MENINGEAL
2.AURICULAR(ALDERMANN’S
NERVE)

12. • INFERIOR GANGLIA
1. PHARYNGEAL
2.CAROTID
3.SUPERIOR LARYNGEAL
4.RECURRENT LARYNGEAL
5.CARDIAC (superior and inferior cervical cardiac branch)

13. Meningeal branch
• It arises from the superior ganglion
• takes a recurrent course, and enters
the cranial cavity through the
jugular foramen to supply the dura
mater of the posterior cranial fossa.

14. • Auricular branch (Arnold’s nerve or
Alderman’s nerve)
• It arises from the superior ganglion,
Enters the mastoid canaliculus on the lateral
wall of the jugular fossa, and emerges through
the tympanomastoid fissure just behind the
external auditory meatus .
Reaches and supplies the skin.
SUPPLIES:
• Concha, root of the auricle
• posterior half of the external auditory meatus
• Tympanic membrane
Stimulation of this nerve, as in syringing of
the ear, may cause reflex coughing (ear cough),

15. Pharyngeal branch
• It arises from the inferior ganglion,
• passes forward between the internal and
external carotid arteries and enter
pharynx at upper border of middle
constrictor and takes part in the formation
of pharyngeal plexus.
• It supplies:
(a) all the muscles of pharynx except the
stylopharyngeus,which is supplied by the
glossopharyngeal nerve,
(b) and all the muscles of soft palate except
the tensor palati which is supplied by the
mandibular nerve (through the nerve to
medial pterygoid).

16. Branches to carotid body
It arises from the inferior ganglion to gives
branches carotid sinus and carotid body
(baroreceptor reflex,chemoreceptor reflex with
IX cranial nerve )
Superior Laryngeal Nerve (mixed,and nerve of
4th arch):
Arise from the inferior ganglion of the vagus
nerve. Moves forwards on the superior
constrictor Passes between the external and
internal carotid arteries.
At the level of greater cornu of the hyoid bone
divides into external and internal branches.

17. External Laryngeal Nerve(motor)
Accompanies the SuperiorThyroid
artery Pierces the inferior Constrictor
and supplies cricothyroid muscles
Also branches to inferior constrictor +
pharyngeal plexus
Supplied areas
cricothyroid muscle

18. INTERNAL LARYNGEAL NERVE (mainly
sensory but some secretomotor function )
travels medially along the superior laryngeal branch of
the superior thyroid artery and pierces the thyrohyoid
membrane
The nerve then runs submucosally in the lateral wall of
pyriform fossa. It supplies sensory fibers to the larynx
above the level of the glottis and to the
laryngopharynx.
The nerve of Galen is a small branch which arises from
the internal laryngeal nerve to anastomose with the
posterior branch of the recurrent nerve to form ansa
galeni, which has a sensory function.
Supplied areas
• Sensory Supplies the mucous membrane of larynx
Above the level of vocal cords
• mucous membrane of the pharynx,
epiglottis,vallecula, and the posteriormost part of the
tongue.

19. RIGHT RECURRENT LARYNGEAL
NERVE (mixed,nerve of 6th arch):
• Nerve Arises from vagus in neck in
front of right subclavian artery Winds
backwards below the artery Runs
upwards behind SUBCLAVIAN AND
COMMON CAROTID ARTERIES
• Reach the trachea- oesophageal
groove; related to Inferior Thyroid
Artery Passses deep to the lower
border of the INFERIOR
CONSTRICTOR
• Enters larynx behind the
CRICOTHYROID JOINT

20. AREAS SUPPLIED
Recurrent laryngeal nerve All intrinsic muscles of larynx, except the
cricothyroid
Sensory nerves to the larynx below the level of vocal cords
Cardiac branches to the deep cardiac plexus ,Branches to trachea
oesophagus, and Inferior constrictor

21. Cervical Cardiac branches
branches off : Superior and
Inferior
Total 4 :Out of which the three go
to the deep cardiac plexus
Left inferior goes to superficial
cardiac plexus
cardiac plexus parasympathetic
innervation to SA node and AV
node
cause decrease depolarisation
leads to decrease heart rate.

22. IN THORAX
• left recurrent laryngeal nerve
• cardiac branch contribute in formation of
cardiac plexus
• oesophageal branch forms (
oesophageal plexus)
• bronchial branch form( pulmonary
plexus ). parasympathetic innervation
cause bronchoconstriction
• IN ABDOMEN
gastric branches
hepatic branches
coeliac branches

23. LEFT RECURRENT LARYNGEAL
• Arises from Vagus in the thorax
• Loops around Ligamentum arteriosum
reaches the tracheooeso-phagal groove
Usually posterior to the inferior thyroid
artery
• Areas supplied similar to right RLN

24. Abdominal branch
• vagus nerve provide
parasympathetic innervation
to majority of abdominal
organ.
• gastric
• hepatic
• coeliac branch up to splenic
flexure of colon
function
it stimulate smooth muscle
contraction and glandular
secretion

27. • CLINICAL ASPECT
• Alderman’s nerve phenomenon:
• The tickling of the cutaneous distribution of the vagus nerve stimulates jaded
appetite.
• The Alderman in ancient Roman days used to stimulate their appetite by
dropping cold water behind the ear supplied by the auricular branch of the
vagus nerve.
• For this reason, the auricular branch of the vagus nerve is also called
Alderman’s nerve. Apparently, this occurs by a reflex increase in gastric
motility supplied by the vagus nerve (to the stomach).

30. The bilateral higher lesions of vagus nerve cause:
(a) nasal regurgitation of the swallowed liquids,
(b) nasal twang of voice,
(c) hoarseness of voice,
(d) flattering of palatal arches,
(e) cadaveric position of vocal cards,
(f) dysphagia, and
(g) loss of cough reflex

31. 1. Vagal trunk above the nodose ganglion-combined abductor paralysis
(cadaveric position)
2. Vagus nerve below the nodose ganglion/recurrent laryngeal nerve-
recurrent laryngeal nerve paralysis (paramedian cord position)
3. Superior laryngeal nerve alone-superior laryngeal nerve paralysis
(bowing of the cord).
AUTONOMIC EVALUATION
Bilateral vagi dysfunction associated with tacchycardia and other sign of
sympathetic overacitvity
Vagotomy in peptic ulcer disease.

32. MY REFERANCES
GRAYS ANATOMY
VISHRAM SINGH
HAZARIKA