Nerve Supply of Head and Neck & Its Applied anatomy

Presented By:
DR. SUSMITA SHAH
MDS Part- I
Department of Paediatrics & Preventive Dentistry
K.M.S.D.C.H
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CONTENT:
• Introduction
• Basic Neuroanatomy
• Origin Of Nervous System
• Division Of Nervous system
• Cranial Nerves
• Applied Anatomy
• References
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Introduction:
• Nervous system is an organ system containing
a network of specialized cells called Neurons
that transmit signals between different parts
of the body & co-ordinate the actions.
• Consists of -
1.Central Nervous System
2.Peripheral Nervous System
1/13/2019 4• BD Chaurasia’s Human Anatomy(Vol. 3)-5th Edition
• Gray’s Anatomy-40th Edition

Terminologies
• NUCLEUS: Applies to an aggregate of nerve cell
bodies located within the CNS
• GANGLION: is a group of nerve cell bodies
situated outside the brain and spinal cord.
• TRACT: defined as a group of nerve cell
processes within the CNS.
• NERVE: is a bundle of neuronal processes
outside the CNS.
• PLEXUS: site of intermingling and regrouping of
peripheral nerve fibers deriving from diverse
origins

FUNCTIONAL COMPONENTS:
• Functions performed by each type of fiber
contained within a given nerve, as a class the
several specialized fiber types referred by the
generic term Functional Components
A)1.General: refers to stimuli conducted throughout
the entire body, common to both cranial & spinal nerves
2.SPECIAL: Afferent information is encoded by highly
specialized sense organs and transmitted to the brain in
certain cranial nerves (I, II, VII, VIII, IX)
B)1.SOMATIC: Refers to skin and muscles of body wall
2.VISCERAL: Organs within the body cavities
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• BD Chaurasia’s Human Anatomy(Vol. 3)-5th Edition

C) 1.AFFERENT: or sensory means the direction of
conduction is towards the CNS
2.EFFERENT: or motor means the direction of
conduction is away from CNS ( Brain to effector )
D) 1.GENERAL AFFERENT: fibers carry sensations
of pain, temperature, touch and pressure from widely
distributed receptors to brain.
2.GENERAL EFFERENT: Includes all motor fibers
to skeletal muscles, smooth muscles, cardiac muscle
or glands.

Various combinations of terms to describe
4 General Functional Component Types:
3 Special Functional Component Types
V
SSA SVA SVE
GSA GSE GVA GVE

Origin Of Nervous System
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• Frank H. Netter Atlas Of Human Anatomy-7th Edition
• Inderbir Singh – Human Embryology – 10th Edition

CENTRAL NERVOUS SYSTEM
Brain- control center of nervous
system receives sensory input from
spinal cord as well its own nerves.
ex: olfactory, optic
Spinal cord- conducts sensory
information from PNS to brain.
• Conducts motor information
from brain to our various effectors
• Serves as minor reflex center
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Peripheral Nervous System
• Cranial nerves: means by which receives
information from and controls activities of
head and neck and to a lesser extent the
thoracic and abdominal viscera.
• Spinal nerves: means by which CNS
receives information from and controls
activities of trunk and limbs.
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Autonomic Nervous System
• Division of PNS.
• Automatically controls
involuntary functions.
• Consists motor neurons
arising from brainstem and
spinal cord that carry
nerve impulses to smooth
muscle in glands, blood
vessels, cardiac muscle
and other organs.
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Divisions of ANS
SYMPATHETIC NERVOUS
SYSTEM:
Typically excitatory, prepares
body for stress. Ex: increase in
heart rate, slowing the
movement of intestines.
PARA SYMPATHETIC
NERVOUS SYSTEM:
Restores /maintains
energy. Ex: slowing
heart rate, speeding
up movement of
intestines.
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Names of Cranial Nerves
I. Olfactory nerve
II. Optic nerve
III. Oculomotor nerve
IV. Trochlear nerve
V. Trigeminal nerve
VI. Abducent nerve
VII. Facial nerve
VIII.Vestibulocochlear nerve
IX. Glossopharyngeal nerve
X. Vagus nerve
XI. Accessory nerve
XII. Hypoglossal nerve
XIII. Terminal Nerve

1. OLFACTORY NERVE
Function: smell
Cells of origin: olfactory
mucosa in the nasal cavity
Component: SA
Exit from skull:
cribriform plate of ethmoid
bone
It carries SA fibers, its
sensory neurons have
Peripheral processes
receptors in the nasal
mucosa
Central processes- return
information to brain

Applied Anatomy of Olfactory Nerve
 Anosmia: loss of olfaction
unilateral/bilateral
 Hyperosmia: Hysterias
Unilateral- frontal lobe tumors
Bilateral- Common colds,other
forms of rhinitis,severe anterior
cranial fossa injury
• Clinical Testing- Each nostril
tested separately using
common test odours.

2. OPTIC NERVE
• Nerve of sight
Functional component: SA
Exit from skull: optic canal
• Structure:
- each optic nerve contains
1.2 million myelinated
fibers
- 4 cm long
- enclosed in 3 meningeal
sheaths

Applied Anatomy of Optic Nerve
• Lesions involving the retina or optic nerve on
one side result in unilateral symptoms.
Optic Nerve Hypoplasia – underdevelopment
Optic Neuritis – Inflammation of Optic Nerve
Unilateral blindness - complete destruction
 Scotoma -partial alteration in vision
Optic atrophy - primary/secondary
Injury to the Optic Nerve- congenital or
hereditary problems, trauma ,toxicity,
inflammation or aneurysms

3. OCCULOMOTOR NERVE
Supplies muscles of eye, superior ,inferior,
medial rectus muscle, inferior oblique,
circular muscles, cilliary muscles
Functional components
a) SE- movements of eyeball
b) GSE- contraction of pupil &
accommodation
c) GSA- for impulses from muscles of
eyeball
Exit from skull: Superior Orbital Fissure
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Applied anatomy of occulomotor nerve
• Lesions: tumors, hemorrhage, aneurysm
of circle of Willis that completely paralyze
the nerve shows :mydriasis, divergent
strabismus, diplopia, loss of light and
accommodation reflexes, slight proptosis.
• Weber’s syndrome: midbrain lesion
causing contra lateral hemiplegia and
ipsilateral paralysis
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Clinical testing of 3rd nerve
• Finger following tests: patient instructed
to follow examiner’s finger.
Determine whether paralysis of one or more
extra ocular muscles.
• A pocket torch shown onto the eye, from the
side to eliminate an accommodation reflex .
This is tested by asking to focus upon an
object approaching him.
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4. TROCHLEAR NERVE
 Functional components
SE: movements of eyeball
GSE: For impulses from
superior oblique muscles
 Function: innervates
Superior oblique muscle
 Exit from skull: superior
orbital fissure
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Applied anatomy of trochlear nerve
• When trochlear nerve is
damaged:
diplopia occurs on looking
downwards. Vision is single so
long as the eyes look above
the horizontal plane.
Cause: brainstem lesion along
nerve course
-orbital fracture
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1/13/2019 BD Chaurasia’s Human Anatomy(Vol. 3)-5th Edition 25

5. Trigeminal Nerve
• V cranial nerve
• Largest among all cranial nerves
• Mixed nerve (motor + sensory)
• Functional Components: GSA,SVE
Sensory supply
• To face
• The greater part of the
scalp,
• The teeth,
• The oral
• Nasal cavities
Motor supply
• muscles of mastication
• Anterior belly of
diagastric
• Mylohyoid
• Tensor tympani
th

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Frank H. Netter Atlas Of Human Anatomy-7th Edition

Nucleus of trigeminal nerve
• A cranial nerve nucleus is collection of neurons in the
brain stem that is associated with one or more cranial
nerves.
• Axons carrying information to and from the cranial
nerves form a synapse first at these nuclei .
There are four nuclei, one motor & three sensory.
• Branchial Efferent: Motor nucleus of trigeminal in upper
pons, for masticatory muscles, mylohyoid & tensor palati.
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• Somatic Efferent: Three sensory nuclei of
trigeminal
a. Mesencephalic nucleus - mid brain, for
proprioception from muscles of mastication, TMJ
and teeth.
b. Principle sensory nucleus - upper pons, for touch
& pressure.
c. Spinal nucleus - lower pons, medulla & upper
cervical spinal cord, for pain and temprature from
face
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Sensory root
Fibers of sensory root
Reach semilunar ganglion
Present at petrous part of temporal bone in Meckel's
cave
Lateral aspect pons and terminate
Three branches
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Motor root
Fibers from motor nucleus
Located in upper pons
Pass from pons along medial side
Medial side of semilunar ganglion
Leave foramen ovale
Supply muscles of mastication
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Ganglion
• A collection of the nerve cell bodies outside
the central nervous system
• Within the middle cranial fossa, the sensory
root expands into the trigeminal ganglion
• Located lateral to the cavernous sinus, in a
depression of the temporal bone known as
the trigeminal cave or Meckel’s cave.
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1. Ophthalmic Division of Trigeminal
Nerve
 Smallest branch of trigeminal
nerve
 Superior division
 Sensory only
 Supplies : eyeballs,
conjunctiva, lacrimal gland,
mucosa of nose ,paranasal
sinus, skin of forehead and
eyelid

Emerges from antero-medial part of
trigeminal ganglion
travel anteriorly through lateral aspect of
cavernous sinus
exit the skull through superior orbital fissure
Trunk 2.5 cm long
Just before exit 3 branches:
Nasocilliary ,frontal ,lacrimal
Course
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Distribution of ophthalmic nerve
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Trigeminal Lateral wall of
Ganglion Cavernous Sinus
Nasociliary Frontal Lacrimal
Lacrimal
Gland,
Conjunctivae
& Skin of
upper eyelid
Supraorbital Supratrochlear
Upper Eyelid, Upper Eyelid,
Conjunctivae Conjunctivae,
& Scalp & Skin of forehead
Frontal sinus MM1/13/2019 38

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BD Chaurasia’s Human Anatomy(Vol. 3)-5th Edition
39

2.Maxillary Division of Trigeminal Nerve
• Entirely sensory
• Origin: semilunar
ganglion
• Exit from skull: foramen
rotundum
• Branches in 4 regions:
-middle cranial fossa
-pterygopalatine fossa
-infraorbital groove &
canal
-terminal branches on
face
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Origin from ganglion
Runs along lower part of cavernous sinus
Middle meningeal nerve
Pass through foramen rotundum
Leaves cranial fossa
Enters pterygo-palatine fossa
Zygomatic
Spenopalatine
PSA
Enters the infra orbital groove
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Maxillary
nerve
zygomatic
Zygomatico-temporal
Zygomatico-frontal
Posterior
superior
alveolar
Mm of max. sinus
Molars and gingiva
Spenopalatine
Infraorbital
Anterior superior alveolar
Middle superior alveolar
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3.Mandibular Division of Trigeminal
Nerve
Largest branch of trigeminal nerve
Emerges from inferior most part of trigeminal
ganglion
Nerve of first branchial arch
Exit from skull: foramen Ovale
It has two roots
- Sensory
-Motor
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Course
• Motor root- from motor
nucleus in pons
• sensory root-
gasserian ganglion a
a small ant. division
exit through foramen ovale
greater wing of sphenoid
trunk which remain 2-3 mm undivided
infra-temporal fossa
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1/13/2019 46Frank H. Netter Atlas Of Human Anatomy-7th Edition

1/13/2019 47
Handbook of Local Anesthesia By Stanley Malamed – 6th Edition

Applied Anatomy of Trigeminal
Nerve
Injury to
1.Opthalmic Nerve- loss of corneal blink reflex
2.Maxillary Nerve- loss of Sneeze reflex
3.Mandibular Nerve- loss of jaw jerk reflex
Hypoacusis- Paralysis of tensor tympani Muscles
Flaccid Paralysis of muscles of mastication
Shingles- Harbors Herpes Zoster Virus
Needle Breakage-asso. with IANB
Trismus
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• Gray’s Anatomy-40th Edition 48

Hematoma
1/13/2019 • Handbook of Local Anesthesia By Stanley Malamed – 6th Edition
49
Management: Apply pressure
-Immediate application of ice
pack
-Takes 7 to 14 days to heal
-Keep moist warm towel in
affected area after 24 hours.
Prevention:
-Don’t penetrate the needle
too deep
-Avoid using long needles

Parasthesia
-Most commonly associated with lingual and
inferior alveolar nerve.
-One of the most frequent cause of dental
malpractice.
Causes:
-Administration of local anesthetic solution
contaminated with alcohol or sterilizing solution.
-Direct trauma to nerve
-Hemorrhage around nerve sheath
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Handbook of Local Anesthesia By
Stanley Malamed – 6th Edition 50

Trigeminal Neuralgia
-John Locke in 1677 gave first full
description with treatment.
-Nicholaus Andre in 1756 coined the term
“Tic Doulourex”.
-John Fothergill in 1773 pubished detailed
description.
-Sudden, Usually Unilateral, Sharp
Shooting, Severe, Stabbing, lancinating,
paroxysmal pain in the distribution of 5th
cranial nerve.
1/13/2019
• Handbook of Local Anesthesia By Stanley Malamed – 6th Edition

Etiology of Trigeminal Neuralgia
PERIPHERAL:
-Dental etiology
-Infections- Herpes zoster
-Multiple sclerosis
-Injuries to nerve
-Nerve compression
CENTRAL:
-Post-traumatic neuralgia
-Intracranial tumors
-Intracranial vascular abnormalities (aneurisms)
-Segmental demyelination
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Clinical Appearance-
*Typical appearance of patient:
*Unshaved face
*Poor oral hygiene
*Frozen or mask like face
*H/O multiple dental extractions
*Triggered by a non painful stimulus
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Diagnosis
*Trigger point
*Paroxysmal pain
*Self limiting
*Refractory period
*Multiple extractions
*Response to carbamazepine

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Differential diagnosis
• Migrane
• Sinusitis
• Odontogenic pain
• Orofacial pain
• Tempromandibular joint disorders
• Post herpetic neuralgia
• Multiple sclerosis
• Glossopharyngeal neuralgia

1/13/2019
Essentials of Medical Pharmacology-K D Tripathi -6th Edition
Textbook Of Oral Medicine- Anil Ghom’s 55
Medicinal Management
Drugs given in combination of carbamazepine
Are:
• Sodium valproate 600mg/day.
• Phenytoin 100mg/day.
• Gabapentin 200mg/day
• Lamotrigine 200mg/day
Tab Clonazepam 1.5 mg/day
Side effects: drowsiness, fatigue, lethargy.
Tab Phenytoin: 100 mg thrice daily.
Side effects: slurred speech, abnormal movements ,gingival hypertrophy, folate
deficiency.

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Peripheral management:
1.Non-destructive:
-Peripheral long acting anesthetic injections
-Nerve decompression
2.Destructive:
-Peripheral Alcohol / Glycerol injections
-Peripheral neurectomy

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Surgical Management
• Internal decompression: - Nerve exposed
in fallopian canal and pressure is relieved.
- Epineural sheath is opened to visualize
the nerve fibers and release adhesions or
re-establish continuity.
• External decompression by releasing of
epineural sheath from surrounding scar
tissue, bone or foreign body.

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Instructions
• Not to drive vehicles
• Not to swim
• Critical jobs like railway driver,
signalman, pilots, working near furnaces,
boilers, towers etc be avoided
• Periodic CBC to rule out hematopoeitic
depression

• Textbook of Human Anatomy-B D
Chaurasia(Vol.3)5ttEdition
• A.K. Datta Essentials Of Human Anatomy Head And Neck.
4th Edition
• Frank H. Netter Atlas Of Human Anatomy-7th Edition
• Inderbir Singh – Human Embryology – 10th Edition
• Handbook of Local Anesthesia By Stanley Malamed –
6th Edition
• Essentials of Medical Pharmacology-K D Tripathi -6th
Edition
• Textbook Of Oral Medicine- Anil Ghom’s
References
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Content
 Abducent Nerve
 Facial Nerve
 Vestibulocochlear Nerve
 Glossopharyngeal Nerve
 Vagus Nerve
 Accessory Nerve
 Hypoglossal Nerve
 Terminal Nerve
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6.Abducent Nerve
-Entirely Motor
-Supplies Lateral Rectus
Muscle of eyeball
-Nucleus: Situated in
pons
-Functional
Components: SE
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63

Course of Abducent Nerve
Emerges from pons(groove between pons
&medulla oblongata)
Passes through Cavernous sinus
Lies below Internal Carotid Artery
Enters Orbit through Superior Orbital Fissure
1/13/2019
• Textbook of Human Anatomy-B D Chaurasia(Vol.3)5ttEdition

Applied Anatomy Of Abducent
Nerve
1.Lesions- damage due to head injuries,
cavernous sinus thrombosis, aneurysm of
internal carotid artery
2.Internal Strabismus-Patient Cannot Turn
Eye Laterally
3.Paralysis-due to increased intracranial
pressure
4.Diplopia-due to paralysis of lateral rectus
muscle
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7.Facial Nerve
• Also Known as “Nerve Of Facial
Expression:”
• It is mixed nerve
• Sensory function-taste from
anterior 2/3rd of tongue
• Motor Function-Supplies facial
muscles, scalp muscles of neck
• Functional Components:
GVE,SVE,SVA & GSA
• Foramen: Internal Acaustic
Meatus & Stylomastoid
Foramen(Facial Canals)
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FUNCTIONAL
COMPONENT
NUCLEI DISTRIBUTION FUNCTION
GVE Superior salivatory
nucleus (lies in the
pons lateral to the
main motor nucleus
of VII )
Submandibular and
sublingual salivary
glands.
Secretomotor
SVE Motor nucleus of
facial nerve (lies in
lower part of pons)
Muscles of facial
expression,
stylohyoid, posterior
belly of digastric,
platysma and
stapedius.
Facial expression
SVA Nucleus of tractus
solitarius (lies in
medullla)
Taste buds in the
anterior 2/3rd of
tongue except
vallate papillae
Taste sensations
GSA Spinal nucleus of
Vth nerve
Part of skin of
external ear
Exteroceptive
sensation

Functions Of Facial Nerve
• Carries taste sensations from the anterior
two thirds of the tongue and oral cavity
• Controls the muscles of facial expression
• It also supplies preganglionic
parasympathetic fibres to several head
and neck ganglia
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 Embryology
 The facial nerve is developmentally
derived from the hyoid arch, which is
the second branchial arch
 The motor division of facial nerve is
derived from the basal plate of the
embryonic pons
 The sensory division originates from
the cranial neural crest
1/13/2019
A.K. Datta Essentials Of Human Anatomy Head And Neck. 4th
Edition
I B SINGH Textbook of Embrology 11th edition 69

• Facial nerve course, branching pattern,
and anatomical relationships are
established during the first 3 months of
prenatal life
• 3rd wk : facioacoustic (acousticofacial)
primordium
• Early 5th week, the geniculate ganglion
forms from distal part of primordium
1/13/2019 I B SINGH Textbook of Embrology 11th edition 70

It separates into 2 branches: main trunk of facial
nerve and chorda tympani
Proximal branches formed in the 6th week, posterior
auricular branch, branch of digastric and stylohyoid
Late 8th week, 5 major peripheral subdivisions
present
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I B SINGH Textbook of Embrology 11th edition
71

GANGLIA ASSOCIATED WITH THE FACIAL NERVE
1/13/2019
Netters : Colour Atlas of Anatomy
72

1. GENICULATE GANGLION
-Derived from Latin GENU = “KNEE”
-L-shaped collection of fibers and sensory
neurons of the facial nerve located in the facial
canal of the head.
-Receives fibers from the motor, sensory, and
parasympathetic components of the facial
nerve
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I B SINGH Textbook of Embrology 11th edition
73

Innervates
i. Lacrimal glands
ii. Submandibular glands
iii. Sublingual glands
iv. Tongue
v. Palate
vi. Pharynx
vii. External auditory meatus
viii. Stapedius
ix. Posterior belly of the digastric muscle
x. Stylohyoid muscle
xi. Muscles of facial expression
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2.SUBMANDIBULAR GANGLION
- Small and fusiform in shape.
-Situated above the deep portion of the submandibular
gland
-The ganglion 'hangs' by two nerve filaments one
anterior and one posterior.
-Receives a branch from the chorda tympani nerve
which runs in the sheath of the lingual nerve
-Innervates submandibular and sublingual salivary
glands
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Vishram Sinagh Textbook of Head and Neck Anatomy 3rd
edition 75

3.PTERYGOPALATINE GANGLION
(meckel's ganglion, nasal ganglion or sphenopalatine
ganglion)
-Ganglion found in the pterygopalatine fossa
-It's largely innervated by the greater petrosal nerve (a
branch of the facial nerve); and its axons project to the
lacrimal glands and nasal mucosa
1/13/2019
Vishram Sinagh Textbook of Head and Neck Anatomy 3rd
edition
76

Branches of facial nerve
1/13/2019
77
Intracranial
Greater petrosal
nerve
Nerve to
stapaedius
Chorda tympani
Extracranial
Posterior Auricular
Nerve
Digastric nerve
Stylohyoid nerve
Terminal
Branches
Temporal branch
Zygomatic branch
Buccal branch
Marginal
mandibular branch
Cervical branch

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78

Various facial Expressions
1/13/2019 79Depressor
Anguli Oris
Buccinator
+Orbicularis
oris muscle
Levator
anguli oris +
risorius
Levator
Anguli
Oris
platysmaMentalisOrbicularis
Zygomaticus
major & minor
OccipitoFrontali
s
Levator labii
superioris
alaeque
nasi
Risorius
Orticularis OrisNasalis +
procerus Nasalis

Applied Anatomy of Facial Nerve
• DISORDERS OF FACIAL NERVE
Facial nerve lesions:
1. Supra-nuclear type
2. Nuclear type
3. Peripheral lesions
(infranuclear)
-Injury at internal acoustic meatus
-Injury distal to geniculate
ganglion
-Injury at stylomastoid foramen1/13/2019
B D CHAURASIA’S Human Anatomy. Volume 3 Edition 4th
80

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82
SUPRA NUCLEAR TYPE:
Features:
-Paralysis of lower part
of face (opposite side)
-Normal taste and
saliva secretion
-Stapedius not
paralyzed
NUCLEAR TYPE
Features:
-Paralysis of facial muscle
(same side)
-Paralysis of lateral rectus
-Internal strabismus
(inward deviation)

PERIPHERAL LESION
(At internal acoustic meatus)
Features
-Paralysis of secretomotor fibers
-Hyper acusis
-Loss of corneal reflex
-Taste fibers unaffected
-Facial expression and movements paralyzed
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Injury at stylomastoid foramen
Condition known as Bell’s Palsy
Weakness of muscles to perform its functions is
called ‘Paresis’
Total flaccidity of facial muscles to perform
motor functions is called ‘Facial Paralysis’
1/13/2019
Grays Anatomy : Textbook of Anatomy 39th Edition
84

Causes
1. Central/Supranuclear
causes
(Facial muscle paralysis
with forehead spared)
-Cerebral mass lesion (e.g.
tumor)
-Cerebrovascular Accident
(typically with ipsilateral
Hemiparesis or
Hemiplegia)
-Multiple Sclerosis
1/13/2019
Grays Anatomy : Textbook of Anatomy 39th
Edition
85
2.Traumatic causes
-Cortical injury
-Temporal Bone
Fracture
-Brain Stem
injury
-Penetrating
middle ear injury
-Scuba Diving

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86
4.Endocrine
causes
-Diabetes Mellitus
-Pregnancy
-Hypertension
-Alcohol Abuse
(Alcoholic -
Neuropathy)
3.Infectious Causes
-Malignant Otitis Externa
(skull base Osteomyelitis)
-Mastoiditis
Varicella Zoster Virus
(Chicken Pox)
-Herpes Zoster Oticus
(Ramsey-Hunt Syndrome) -
Herpetic Vesicles at auricle
and external canal
-HIV Infection
-Influenza
-Parotitis
-Meningitis
-Encephalitis
-Mums
5.Birth
Causes
-Facial
Nerve
Injury from
Birth
Trauma
(forceps
delivery)
-Congenital
Facial Palsy

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87
6. Tumors
-Facial Nerve neuroma
-Cholesteatoma
-Glomus jugular tumor
-Primary Temporal Bone
tumors
-Meningiomas
-Hemangioblastoma
-Pontine glioma
-Parotid tumor
7.Idiopathic Causes:
-Myasthenia Gravis
-Guillain-Barre
Syndrome
-Sarcoidosis
-Familial Bell's Palsy
8.Iatrogenic Causes
-Mandibular block anesthesia
-Head and neck surgery
-Parotid surgery

Testing Of Facial Nerve
• Ask the patient to close his eyes firmly.
• Ask the patient to smile.
• Ask patient to fill the mouth with air. Press the
cheek with your finger and compare the
resistance on two sides
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89

Bell’s Palsy
-First described more than a century ago by Sir
Charles Bell
-Bell palsy is certainly the most common cause of
facial paralysis worldwide
-It is caused due to inflammation of facial nerve near
stylo-mastoid foramen or compression of its fibers
near facial canal.
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90

Etiology
-Main cause of Bell's palsy is latent herpes viruses
(herpes simplex virus type 1 and herpes zoster
virus), which are reactivated from cranial nerve
ganglia
-Polymerase chain reaction techniques have
isolated herpes virus DNA from the facial nerve
during acute palsy
-Cold hypothesis
-Rheumatic
-Immunologic
-Ischemic hypothesis
1/13/2019
Benjamin Stew and Huw Williams. Williams British
Journal of General Practice 2013; 63:109–110. 91

 Clinical Features
1.Unilateral involvement
2.Inability to smile
3.Inability close eye or raise eyebrow
4.Whistling impossible
5.Inability to close eyelid (Bell’s sign)
6.Inability to wrinkle forehead
7.Slurred speech
8.Mask like appearance of face
9.Dribbling of saliva
10.Epiphora
1/13/2019
Benjamin Stew and Huw Williams British Journal of General
Practice 2013; 63:
109–110.
92

1/13/2019
93

Management
• Physiotherapy
-Facial massage
-NeuroMuscular Retraining
• Ocular protection is essential to
protecting vision in both the short term
and long term in patients with facial
paralysis.
• Eye drops-hypromellose drops
• Artificial tears are combined with
ointment at night (Mavrikakis, 2008)
1/13/2019

8. Vestibulocochlear Nerve
• Also called as Auditory Nerve
• It is a sensory Nerve
• Consists of Two Roots -
• 1.Vestibular -Transmits impulses from
vestibular apparatus (balance)
• 2.Cochlear-Transmits impulses from
auditory apparatus (sound)
• Functional Components- SSA
1/13/2019
B D CHAURASIA’S Human Anatomy. Volume
3 Edition 4th 95

Functions
Auditory Nerve transmits sound and
equilibrium (balance) information
from Internal Ear To Brain
1/13/2019
B D CHAURASIA’S Human Anatomy. Volume
3 Edition 4th 96

Applied Anatomy
Deafness
1. Conductive-Failure of sound waves to reach
cochlea
2. Sensorineural-Failure of production or
transmission (cochlear disease)
3. Cortical Deafness-Bilateral posterior temporal
lobe lesion
4. Vertigo-Illusion of rotary Movement due to
disturbed orientation of body in space
5. Tinnitis-Sensation of
burring,ringing,hissing/singing quality
6. Acoustic Neuroma-Slow growing Benign
Tumour1/13/2019
97

9. Glossopharyngeal Nerve
• Originates from Medulla Oblongata
• Nuclei-Inferior salivatory
nucleus,Nucleus ambiguus,Nucleus
Solitory Tract
• Functional components- GVE,SVA,GVA
• Foramen-Jugular Foramina
1/13/2019
98

1/13/2019

Functions
• Sensory Function- Taste sensation from
posterior 1/3rd of tongue, pharynx
• Motor Function-Muscles of speech &
swallowing, parotid salivary gland
• Somatic Motor Function-Muscles of
pharynx, tongue
• Autonomic Motor Function-Saliva
Production
1/13/2019 B D CHAURASIA’S Human Anatomy. Volume 3 Edition 4th 100

 Branches of Glossopharyngeal Nerve
1.Tympanic Nerve (S)
2.Branch to Carotid sinus (S)
3.Branch to Stylopharyngeus Muscle (M)
4.Tonsillar Branches (S)
5.Lingual Branches (S)
6.Pharyngeal Branches (M)
1/13/2019
4tB D CHAURASIA’S Human Anatomy. Volume 3 Edition h
101

Applied Anatomy
1. Lesion to the nerve cause decreased
secretion of parotid gland
2. Absence of taste from post. 1/3rd of tongue
3. No gag Reflex
4. Loss of sensation from tongue, pharynx,
tonsils, soft palate
5. Glossopharyngeal Neuralgia
6. Jugular Foramen Syndrome-Multiple Cranial
Palsies
7. Pharyngitis- Refered pain in ear
1/13/2019 B D CHAURASIA’S Human Anatomy. Volume 3 Edition 4th 102

Glossopharyngeal Neuralgia
• Glossopharyngeal neuralgia is an irritation of
the ninth cranial nerve causing extreme pain
in the back of the throat, tongue and ear.
• Attacks of intense, electric shock-like pain can
occur without warning or can be triggered by
swallowing.
• Symptoms include pain in Nasopharynx, or
back of the nose and throat, Back of the
tongue, Ear, Tonsil area, Larynx or voice box.
1/13/2019
103

Treatment For
Glossopharyngeal Neuralgia
1. Pain control
2. Antiseizure drugs like Carbamazepine
3. Antidepresssant Drugs
4. Surgical Management
1/13/2019
• Grays Anatomy : Textbook of Anatomy 39th Edition
• B D CHAURASIA’S Human Anatomy. Volume 3 Edition 4th 104

10. Vagus Nerve
• Also known as ”Wandering Nerve”
• Originates from medulla oblongata
• Foramen- Jugular Foramina
• Nuclei-nucleus ambigus ,nucleus
solitary(superior part & inferior part)
• Sensory Function-supplies skin of back
of ear, external acaustic meatus, part of
tympanic membrane, larynx, trachea,
oesophagus, thoracic & abdominal
viscera, epiglottis, root of tongue.
1/13/2019 4tB D CHAURASIA’S Human Anatomy. Volume 3 Edition h 105

• Motor Function-supplies throat, Heart,
Lungs, abdominal Viscera, soft palate
• Associated with Derivatives of fourth
pharyngeal arch
• 8-10 rootlets are present
• Functional Components-
SVA,SVE,GSE,GVE,SSA,GSA
• Types of Fibers- 1.Brachial Motor
2.Visceral Motor
3.Visceral Sensory
4.Special Sensory
5.General Sensory

Vagus Nerve
Carotid Sheath
Travels inferiorly with internal jugular vein &
Common Carotid artery
At the base of neck divides into Right & Left
1/13/2019 4tB D CHAURASIA’S Human Anatomy. Volume 3 Edition h
107
Right nerve passes anterior to
subclavian artery & posterior to
sternoclavicular joint entering
Thorax
Left nerve passes inferiorly
between the left common
carotid & left subclavian artery,
posterior to sternoclavicular
artery entering Thorax

 Applied Anatomy Of Vagus Nerve
1. Lesion -Difficulty in swallowing, speech(affects
pharyngeal & superior laryngeal branches)
2. Recurrent Laryngeal Nerve Palsies-common
due to malignant disease & due to damage
during surgical operations
3. Vagus Nerve Palsy- Uvula Pulled Towards
Normal Side
4. Aphonia- Paralysis of both vocal cords
5. Viral infection(Sensory Ganglion)-Herpes
Zoaster

11. Accessory Nerve
• Foramen- Jugular Foramena
• General Destination-soft palate, throat,
muscles of neck
• Nucleus- Hypoglossal Nucleus
• Somatic Motor Function- Swallowing &
Head Movement (trapezius &
sternocleidomastoid)
• Functional Components- SVE,GSE
1/13/2019
4tB D CHAURASIA’S Human Anatomy. Volume 3 Edition h
109

Course
Medulla Oblongata
Hypoglossal Canal
Behind Vagus Nerve
Between IJV & ICA
Posterior Belly of Digatric
Tongue(Extrinsic & Intrinsic Muscles

It Supplies
• Extrinsic Muscles-Genioglossus,
Hyoglossus, Styloglossus
• Intrinsic Muscles- Superior
Longitudinal, Inferior Longitudinal,
Verticals, Tranversus

1/13/2019
112

Applied Anatomy of Spinal Accessory Nerve
• Torticollis/wry neck
• Lesion-Drooping of shoulder & Inability
to turn chin to opp. Side
• Unilateral motor neuron weakness
1/13/2019
• B D CHAURASIA’S Human Anatomy. Volume 3 Edition 4th
• Vishram Singh Textbook of Head and Neck Anatomy 3rd edition
113

12. Hypoglossal Nerve
• It is a Motor nerve
• Functional Components- GSE
• Supplies intrinsic & Extrinsic Muscles of
tongue
• Foramen- Hypoglossal Canal
• Somatic Motor Function- Speech &
swallowing via muscles of tongue
1/13/2019
• Vishram Singh Textbook of Head and Neck Anatomy 3rd edition 114

1/13/2019 115
2. Extracranial segment
Nasopharyngeal Carotid space Sublingual Segment
a.Medullary Segment
b. Cisternal Segment c. Canalicular Segment
Hypoglossal Nucleus
1. Intracranial Segment

1/13/2019

 Applied Anatomy of Hypoglossal
Nerve
• Supranuclear Lesion-Parlysis eithout
wasting-tongue moves sluggishly
• Defective speech
• Tongue Deviates on Protrusion-
Unilateral Lingual Paralysis
• Injury to the nerve causes dysarthria
& dysphagia
1/13/2019

Causes
-The causes may be central or peripheral & include
cerebrovascular accidents, brain stem tumours &
infections
Speech Characteristics- abnormality of tongue leads
to misarticulation
-Problem while saying (T, D, L, I, J, N, K, G)
1/13/2019 118

Managent
• Speech therapy should be given
• Exercise for treatment of dysarthria
may improve tongue co-ordination &
strength
• Surgical management for hypoglossal
nerve injuries
1/13/2019
• B D CHAURASIA’S Human Anatomy. Volume 3 Edition 4th 119

13. Terminal Nerve
• Also known as “Zero Nerve”
• Initially referred as nerve of Pinkus.
• First discovered in 1870 in sharks and other
types of fish
• Termed as Terminal –it was observed to
extend into the region of lamina terminalis
• Published 1987 as X||| Cranial nerve as Zero
nerve –it is more rostral than other cranial
Nerves
1/13/2019 120

1/13/2019 121
• References
• Vishram Singh Textbook of Head and Neck Anatomy 3rd
edition
• Netters : Colour Atlas of Anatomy
• I B SINGH Textbook of Embrology 11th edition
• Fujiwara T et al. High-dose corticosteroids improve the
prognosis of Bell’s palsy compared with low-dose
corticosteroids: A propensity score analysis. Auris Nasus
Larynx (2017)
• Alptekin D O. Acupuncture and Kinesio Taping for the acute
management of Bell’s palsy: A case report Complementary
Therapies in Medicine 35 (2017) 1–5.

Nerve Supply of Head and Neck & Its Applied anatomy

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