Facial Nerve, XI, X and XII, Cervical Plexus Condensed Grayscale Slides

7/27/2019 Facial Nerve, XI, X and XII, Cervical Plexus Condensed Grayscale Slides

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Facial Nerve (VII), IX & XIIFacial Nerve (VII), IX & XII

Alex ForrestAssoci ate Profess or of For ensic Od ontol ogyForensic Science Research & Innovation Centre, Griffith UniversityConsultant Forensic Odontologist,Queensland Health Forensic and Scientific Services,

39 Kessels Rd, Coopers Plains, Queensland, Australia 4108

Oral Biology

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Do not remove this notice

Learning ObjectivesLearning Objectives

You should be able to describe VII and its importance in

dental practice.

You should be able to understand and explain the role of IX in

the innervation of the tongue and oropharynx, and theimportance of the gag reflex.

You should be able to understand and explain the role of X in

the innervation of the oropharynx.

You should understand the basic functions of XII.

You should be able to discuss the cervical plexus and its

branches.

This session considers the facial nerve, cranial nerve VII.

This nerve is important to a dentist because it can

inadvertently be anaesthetized while an inferior dental

block injection is being performed.

VII - Facial NerveVII - Facial Nerve


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It can be injured both from trauma and from surgery.

There are various conditions that can affect this nerve.

We need to know its structure and its functions, so we can

diagnose problems and predict and manage the outcomesin our patients.

VII - Facial NerveVII - Facial Nerve Learning ObjectivesLearning Objectives

You should be able to understand and explain the

structural and functional aspects of the anatomy of VII

You should be able to understand and explain in detail

the role of the chorda tympani in taste and innervationof major and minor salivary glands

Learning ObjectivesLearning Objectives

You should understand and be able to explain the

causes, consequences and management of accidental

anaesthesia of VII.

The facial nerve contains a small general sensorycomponent which provides common sensation to parts of

the external ear, and also a special sensory component

which is responsible for innervating taste buds.



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The somatic motor component (the largest part of this

nerve) provides the motor supply to the muscles of facial

expression and other muscle derivatives of the second

branchial arch.

There is a parasympathetic secretomotor component that

travels with both the facial nerve and lingual nerve of the

trigeminal nerve to the sublingual, submandibular and

lacrimal glands.

VII - Facial NerveVII - Facial Nerve Facial Nerve OriginFacial Nerve Origin

The Facial Nerve

arises from the

pons caudal to

the trigeminal

nerve, close to

the position of the

internal acousticmeatus through

which it passes

with VIII.

From Grays Anatomy, Longman, London, 35 th Edition, 1973. p 1012.

Facial Nerve OriginFacial Nerve Origin

It comprises two

roots - a larger motor

root and a smaller

sensory root. The

motor root is simply

named the motor root

of VII, but thesensory root is

sometimes called

nervus intermedius

because it lies

sandwiched between

the motor root of VII

and the trunk of VIII

in this location. From Grays Anatomy, Longman, London, 35 th Edition, 1973. p 1012.

The large motor root carries the motor fibres to themuscles of facial expression, the posterior belly of the

digastric muscle, the stapedius and the stylohyoid,

because all of these structures are derived from the

second branchial arch.



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The sensory root carries general sensory fibres to parts of

the external ear, and also carries the special sensation of

taste to the anterior two-thirds of the tongue and also to

the palate.

VII - Facial NerveVII - Facial Nerve VII - Facial NerveVII - Facial Nerve

The sensory root contains some parasympathetic

secretomotor fibres as well, and these supply the

submandibular and sublingual salivary glands, as well as

the lacrimal glands and the minor mucous glands of thenose and palate.


The motor root and

nervus intermedius

run together with the

vestibulocochlear

nerve (VIII, also

known as the auditorynerve) into the internal

acoustic meatus in the

temporal bone.

The facial nerve runs

superiorly to VIII in a

groove along its upper

surface. From Grays Anatomy, Longman, London, 35 th Edition, 1973. p 1012.


The facial nerve and the

vestibulocochlear nerves

soon separate in their

courses.

VIII moves off towards theinner ear, but the two roots of

VII join soon after it enters

the internal acoustic meatus,

and they continue as a single

nerve trunk in the facial

canal which angles obliquely

forwards through the petrous

temporal bone.From Grays Anatomy, Longman, London, 35 th Edition,

1973. p 1012.


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Facial Nerve CourseFacial Nerve Course

The nerve runs forward and laterally in the facial canal

until it comes close to the cavity of the middle ear.

At this point, it turns sharply posteriorly and inferiorly and

heads downwards towards the stylomastoid foramen.

At the bend, the nerve trunk

becomes swollen into the

geniculate ganglion, where

the nerve cell bodies of the

somatic sensory nerves are

stored.

The bend is given the nameexternal genu, after the

Latin word for knee, genu

(from which the word

genuflect comes).

From Grays Anatomy, Longman, London, 35 th Edition,

1973. p 1012.


As the facial nerve

reaches the external

genu, it gives off an

important branch

called the greater

petrosal nerve, or

sometimes the

greater superficial

petrosal nerve.

This nerve arises

from the geniculate

ganglion.



Fibres from this ganglion are mainly taste fibres for the

palate, but it contains parasympathetic secretomotor

fibres for the lacrimal gland and minor salivary glands as

well.



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The greater petrosal nerve

runs forward and medially in

a small canal to emerge

from a tiny hole on the

cranial surface of the

petrous temporal bone

called the hiatus for the

greater superficial petrosalnerve, and runs medially

and slightly anteriorly in a

groove in the floor of the

middle cranial fossa.From Grays Anatomy, Longman, London, 35 th Edition,

1973. p 1012.


It continues

underneath the

trigeminal ganglion to

run over the roof of

foramen lacerum

towards a small

canal in its anterior

wall of foramen

lacerum called thepterygoid canal

which opens into the

pterygopalatine

fossa.From Grays Anatomy, Longman, London, 35 th Edition, 1973. p 1012.


Here the parasympathetic secretomotor fibres for the lacrimal

gland and the minor salivary glands of the palate and upper lip

synapse, and their postganglionic fibres follow the branches of the

trigeminal nerve to get to their final destinations.



Taste fibres do not synapse in the pterygopalatine ganglion

because they are not parasympathetic fibres, but pass to

the palate via the greater and lesser palatine nerves of V2.




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Parasympathetic secretomotor fibres to glands of the nasal

cavity travel in the sphenopalatine nerve.



After the external genu,

the trunk of the facial

nerve turns backwards

and downwards to run

towards the stylomastoid

foramen.

When it is about 5-6 mm

from this foramen, andstill in the facial canal, it

is very closely related to

the cavity of the middle

ear, which sits just

anterior to it.

From Grays Anatomy, Longman, London, 35 th Edition, 1973.

p 1012.



In this position, the facial

nerve is vulnerable to

damage arising from

operations performed onthe middle ear.

Here, it gives off a small

but very important

branch called the chorda

tympani.


1973. p 1012.

Chorda TympaniChorda Tympani

This small nerve provides the parasympathetic

secretomotor fibres to the submandibular and sublingual

salivary glands and to the minor glands of the floor of the

mouth, as well as providing taste fibres to the anterior

two-thirds of the tongue.


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Facial NerveFacial Nerve

It does this by

"hitching a ride"

with the lingual

nerve of V3.

However, it needs

to get to the

lingual nerve, and

at this point it isstill deep within

the temporal

bone.

From Grays Anatomy, Longman, London, 35 th Edition, 1973. p 1008.From Grays Anatomy, Longman, London, 35th Edition, 1973. p 1008.

Facial BranchesFacial Branches

Once it is in the parotid gland, the nerve gives off motor

branches to the posterior belly of the digastric and

stylohyoid muscles.


The nerve nowgives off five

major branches

that spread to

cover the face.

Scott JH & Dixon AD. Anatomy for Students of Dentistry. 3 rd

Edition, Churchill Livingstone, Edinburgh, 1972. p. 512


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They contain the bulk of the motor fibres of the large

motor root of this nerve, and they are distributed to the

muscles of facial expression to which they supply motor

function.

ParalysisParalysis

Paralysis of this nerve can therefore occur if one

inadvertently deposits local anaesthetic solution into the

parotid gland.

ParalysisParalysis

Sometimes a deep lobe

of the gland occurs

close to the positionwhere the inferior dental

block is to be

administered.

Modified from: Haglund, J. & Evers, H Local

Anaesthesia in Dentistry, Astra Lkemedel

Sdertlje, 2nd Edition, 1975. p. 52.

ParalysisParalysis

When this happens, all

the branches of the

facial nerve in the

gland become

anaesthetized,

resulting in facial

paralysis on the

affected side.

Illustrated Handbook in Local Anaesthesia, Ed: E. Eriksson,

Munksgaard, Denmark, 1969, p.67.


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Motor SupplyMotor Supply

These branches supply motor fibres to muscles of facial

expression in their immediate vicinity.

IX Glossopharyngeal

Nerve

The glossopharyngeal nerve exits the upper part of the

medulla oblongata below the pons by a few filaments which

contain both sensory and motor fibres.

It supplies motor fibres to stylopharyngeus, secretomotor

fibres to the parotid gland, and sensory fibres to the pharynx,

tonsil, and the back of the tongue.

It also supplies taste fibres to the posterior 1/3 of the tongue.

IX - Glossopharyngeal NerveIX - Glossopharyngeal Nerve



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Sensory nuclei :

nucleus of the solitary tract (taste)

nucleus of the spinal tract (common sensation)

Motor nuclei :

nucleus ambiguus

inferior salivatory nucleus (parotid gland)


The nerve leaves the cranium through the anterior part of the

jugular canal together with X and XI, and becomes covered in

a layer of dura mater as it approaches the opening of the canal.

Netter, F. 1989, Atlas of Human Anatomy, Summit, New Jersey, Ciba-Geigy Medical, Plate 120.


Netter, F. 1989, Atlas of Human Anatomy, Summit, New Jersey, Ciba-Geigy Medical, Plate 120.

As it passes through the canal, it features two small swellings

called thejugular or super io r, and pet rosal or in fer ior

ganglia.

IX - Glossopharyngeal NerveIX - Glossopharyngeal Nerve IX - Glossopharyngeal NerveIX - Glossopharyngeal Nerve

Netter, F. 1989, Atlas of Human Anatomy, Summit, New Jersey,

Ciba-Geigy Medical, Plate 119.

The superior ganglion

is regarded as a

detached part of the

larger inferior one so

they basically make upone single classical

sensory ganglion

between them, and

they therefore contain

the cell bodies of the

sensory fibres.


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Tympanic Branch of IXTympanic Branch of IX

The tympanic

branch is a

tiny branch

given off just

after IX leaves

the jugularcanal.

Netter, F. 1989, Atlas of Human Anatomy, Summit, New Jersey, Ciba-Geigy

Medical, Plate 119.


If you look carefully on a skull, you may see a small foramen in

between the jugular canal and the carotid canal, and it is

through this foramen that the tympanic branch passes into the

tympanic canaliculus.

Modified from:

McMinn, R &

Hutchings, R. A

Colour Atlas of

Human Anatomy.

Wolfe Medical

Publication,

Netherlands, 2nd

Edition 1988.

p.58.


The tympanic

canaliculus takes

the tympanic

nerve up to the

middle ear, and

here it joins witha branch of the

facial nerve (VII)

to form the

tympanic plexus

in the wall of the

middle ear.


Medical, Plate 119.



Medical, Plate 119.

The most

important branch

of this plexus is

the lesser

superficial

petrosal nerve,which contains

parasympathetic

secretomotor

fibres from IX

originating in the

inferior salivatory

nucleus.


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It runs in a small

canal to appear

on the floor of

the middle

cranial fossa just

laterally to the

hiatus for thegreater

superficial

petrosal nerve.


Lesser Petrosal NerveLesser Petrosal Nerve

Here it lies in a small

groove, parallel and

just laterally to the

greater petrosal

nerve, and passes

through foramen

ovale or sometimes

through the

canaliculus

innominatus, which

lies medial to

foramen spinosum.From Grays Anatomy, Longman, London, 38 th Edition, 1989. p 1107.



1989. p 1105.

It turns inferiorly to pass

through the canal or

foramen, and then runs to

the otic ganglion, aparasympathetic ganglion

associated with the

mandibular division of the

trigeminal nerve which lies

deep to the main nerve

trunk.


From Grays Anatomy, Longman, London, 38 th Edition, 1989. p

1105.

Postganglionic

secretomotor fibres

then run in theauriculotemporal

nerve to reach and

supply the parotid

gland.



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Tonsillar BranchesTonsillar Branches

The tonsillar branches ramify to form a plexus in the region

of the palatine tonsil, and are distributed to provide

sensation in the upper part of the pharyngeal wall and

around the auditory tube.

They are not important to us in this course.

Lingual BranchesLingual Branches

The lingual branches

run deep to the

hyoglossus muscle of

the tongue, and supply

general sensation and

taste to the posteriorone-third of the

tongue.


X Vagus NerveThis nerve contains both sensory and motor components,

and has a wider distribution than any other cranial nerve.

The term vagus means wandering.

It does not feature separate sensory and motor roots, but it

does have sensory ganglia like IX.

X - Vagus NerveX - Vagus Nerve


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Its sensory fibres are distributed to the larynx and

epiglottis.

It also contains visceral components distributed to the

autonomic muscles of the heart, bronchi, and most of the

digestive tract, and also some taste fibres.

It provides motor innervation to the muscles of the larynx,

and is important in speech.


The vagus nerve leaves the cranium through the jugular

canal with IX and XI. It has two ganglia like IX.

The superior ganglion lies in the jugular canal, and the

inferior ganglion is found after the nerve exits the canal.

Both ganglia contain the nerve cell-bodies of somaticsensory fibres.


It supplies sensory and

motor functions to the

larynx allowing us to

speak.

It works closely with V,

VII, IX and XII to allow

us to articulate words

properly.

From Grays Anatomy, Longman,

London, 38th Edition, 1989. p.

1117

It helps control the

heart rate, innervates

the organs ofrespiration, and has

sensors to help control

the blood pressure.



1117


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It helps us control

digestion and the

movement of food

through most of the

digestive tract as far

down as the

mid-colon.

The distribution of the

vagus in the thorax

and abdomen neednot be known.



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XII Hypoglossal Nerve

The hypoglossal nerve also arises from the medulla as a

series of filaments, which pass behind the vertebral arteryto form a common nerve trunk.

This nerve trunk exits the cranial cavity through the

anterior condylar (hypoglossal) canal.

XII - Hypoglossal NerveXII - Hypoglossal Nerve

It descends in the carotid

sheath and turns

forwards to hook around

the origin of the occipital

artery.

It passes deep to

stylohyoid and enters the

floor of the mouth

between mylohyoid and

hyoglossus muscles.


London, 38th Edition, 1989. p 1119.

XII - Hypoglossal NerveXII - Hypoglossal Nerve


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It communicates with the

lingual nerve and then

penetrates the tongue

below the sublingual

gland.

It supplies the intrinsic

and all the extrinsic

muscles of the tongue

except the palatoglossus,which is supplied by XI

via the pharyngeal

plexus.


London, 38th Edition, 1989. p 1119.

XII - Hypoglossal NerveXII - Hypoglossal Nerve XII - Hypoglossal NerveXII - Hypoglossal Nerve

It is responsible for most movements of the tongue and

plays a critical role in speech and mastication.

If it is injured, the tongue deviates towards the damaged

side when it is stuck out.Why do you think this might be?

Cervical Plexus

When spinal nerves exit the vertebral column, they split into

dorsal and ventral rami. In general, the ventral rami are larger

than the dorsal ones.

In the thoracic region, the ventral rami run independently of

each other and they retain, like all dorsal rami, a more-or-less

segmental distribution.

Nerve PlexiNerve Plexi


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However, in the

cervical, lumbar and

sacral regions, they

unite near their origins

to form plexuses.

http://www.esb.utexas.edu/quinn/

Bio416K/Nervous%20system/Ana

t%2014.7.jpeg

Nerve PlexiNerve Plexi

There are 8 cervical spinal

nerves.

The ventral rami of the upper 4

of these unite to form the

cervical plexus.

Those of the lower 4 unite with

part of the ventral ramus of thefirst thoracic nerve to form the

brachial plexus.

http://www.esb.utexas.edu/quinn/Bio416K/Nervous%20

system/Anat%2014.7.jpeg

Cervical PlexusCervical Plexus

Note that each nerve in the

cervical plexus receives at

least one grey ramus

communicans from the

sympathetic chain.The upper four nerves

receive theirs from the

superior cervical ganglion,

while the 5th and 6th receive

theirs from the middle

cervical ganglion.

http://www.bartleby.com/107/Images/large/image844.gif


The cervical plexus is

formed by the ventral

rami of the upper four

cervical spinal nerves.

It supplies branches to

some of the muscles of

the neck, and to parts of

the skin of the head,

neck and chest.

http://imc.gsm.com/integrated/haonline/haonline/ha/figimgs/25_3.gif



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To make it easier to

understand, we divide the

branches into superficial

and deep groups:

superficial branches

ascending

descending

deep branches

Modified from: Grays Anatomy, Longmans, London, 38th Ed 1989 p.1128

ascending

descending


Superficial Ascending Branches:

Lesser Occipital Nerve

Great Auricular Nerve

Transverse Cervical Nerve

Superficial Descending Branches:

Medial Supraclavicular Nerve

Intermediate Supraclavicular Nerve

Lateral Supraclavicular Nerve


Superficial Ascending

Branches:



Transverse Cervical Nerve


Modified from:

Grays Anatomy,

Longmans,

London, 38th Ed

1989 p.1129


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Superficial

Descending Branches:

Medial Supraclavicular Nerve

Intermediate SupraclavicularNerve

Lateral Supraclavicular Nerve

Modified from:

Grays Anatomy,

Longmans,

London, 38th Ed

1989 p.1129


Medial Deep Branches:

communicating branches with X & XII

muscular branches inc. phrenic nerve & inferior root of ansa

cervicalis

Lateral Deep Branches:

communicating branches with XI

muscular branches

Modified from:

Grays Anatomy,

Longmans,

London, 38th Ed

1989 p.1128


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Modified from: Grays Anatomy, Longmans, London, 38th Ed

1989 p.1129

It loops around the

accessory nerve XI and

ascends along the

posterior border of the

sternocleidomastoid

muscle.

It passes upwards onthe side of the head

behind the auricle of the

ear, where it supplies

skin in this region.


Superficial Ascending BranchesSuperficial Ascending Branches


1989 p.1129

It curves around the

posterior border of

sternocleidomastoid

muscle, just like the

lesser occipital and

ascends on

sternocleidomastoid

beneath the platysmamuscle with the external

jugular vein up to the

parotid gland, where it

divides into an anterior

and a posterior branch.




1989 p.1129

The anterior branch

supplies the skin of the

face in the region

overlying the parotid

gland.

The posterior branch

supplies skin over the

mastoid process and the

lower 2/3 of the back of

the auricle, as well as

the lobule and the

concha of the ear.

Great Aur icular Nerve



1989 p.1129

This nerve curves

around the posterior

border ofsternocleidomastoid to

run obliquely forwards

deep to the external

jugular vein to reach the

anterior border of this

muscle.

Transverse Cervical

(Cutaneous) Nerve



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1989 p.1129

Then it penetrates the

deep cervical fascia and

divides into ascending

and descending

branches deep to theplatysma.

Transverse Cervical

(Cutaneous) Nerve


The ascending branches pass upwards to form a plexus with

the cervical branch of VII, and some pass through platysma to

supply the skin of the upper and front parts of the neck. They

sometimes also form an accessory nerve supply to the

lower incisor teeth.The descending branches pierce platysma to supply the skin

on the front and sides of the neck, as far down as the sternum.

Transverse Cervical (Cutaneous ) Nerve


Modified from: Grays Anatomy, Longmans, London, 38th

Ed 1989 p.1129

These supply skin

down to the

second rib, and

medially to the

midline.

Medial Supraclavicular

Nerves

Superficial Descending BranchesSuperficial Descending Branches


Ed 1989 p.1129

These supply skinoverlying pectoralis

major and the

deltoid muscle.

Intermediate Supra-

clavicular Nerves



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Ed 1989 p.1129


These supply skin

over the upper and

posterior parts of

the shoulder.

Lateral Supra-

clavicular Nerves

Modified from: Grays Anatomy,

Longmans, London, 38th Ed 1989 p.1128

Descendens hypoglossi(superior root)

Descendens cervicalis(inferior root)

Ansa Cervical is

Two components:

Deep BranchesDeep Branches




Motor to all the

infrahyoid strap

muscles with the

exception of the thyro-hyoid, which is supplied

by C1 via a branch

which travels with the

hypoglossal nerve.

Ansa Cervical is




This is the only source

of motor innervation to

the diaphragm. It arises

mainly from C4, butreceives contributions

from C3 and C5.

Three, four and five

Keep the diaphragm

alive!

Phrenic Nerve


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The End

Facial Nerve, XI, X and XII, Cervical Plexus Condensed Grayscale Slides

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