trigminal nerve v3 condensed grayscale slides

7/27/2019 Trigminal Nerve V3 Condensed Grayscale Slides

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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

Trigeminal Nerve: V3Trigeminal Nerve: V3

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Mandibular Division V3Mandibular Division V3

Recall the area

supplied with

sensory innervationby the mandibular

division of thetrigeminal nerve

(V3).

Grays Anatomy, Longmans, London,

38th Ed 1989 p. 1106

The mandibular

division of thetrigeminal nerve,

often known simplyas the mandibular

nerve, contains both

sensory fibres andmotor fibres.

Modified from: Evers, H & Haegerstam, G.

Introduction to Local Anaesthesia, Mediglobe SA,

Fribourg, 2nd Edition 1990. P. 60



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The sensory portion of

the mandibular nerve

passes into the

trigeminal ganglion andfrom there to the

brainstem along withthe sensory fibres from

V2 and V1.

Modified from Grays Anatomy, Longmans, London, 38th Ed 1989

p. 1107



p. 1107

The somatic motor

nerve fibres leave the

pons in a separate

motor root, which joinsthe main trunk of themandibular nerve just

after it exits thecranium through

foramen ovale in thegreater wing of the

sphenoid bone.


Here it forms a common

trunk for a very shortdistance, before giving

off its first branch.


Introduction to Local Anaesthesia,

Mediglobe SA, Fribourg, 2nd Edition, 1990.

P. 60

Mandibular Division V3

This is a small twigcontaining sensory fibres,

and it dives back into the

cranium with the middlemeningeal artery through

foramen spinosum of thesphenoid bone to supply

most of the dura mater

with sensation. It is knownas the recurrent

meningeal nerve, ornervus spinosus.

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

1989 p. 1105



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The common nerve

trunk now gives offsmall muscular

branches containing

motor fibres to thetensor palati and

tensor tympanimuscles, and the

medial pterygoid

muscle.


p. 1105


It also acquires smallcommunicating

branches from the

otic ganglion, a

parasympatheticmotor ganglion which

lies deep to it in theinfratemporal fossa.


p. 1105


The nerve now divides into a larger posterior division and a

smaller anterior division. A general (and inaccurate) rule:

The posterior division is entirely composed of sensory

branches except for one motor one.

The anterior division comprises entirely motor branchesexcept for one sensory one.


Posterior DivisionPosterior Division


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Posterior DivisionPosterior Division

The branches of the posterior division of the

mandibular nerve are:

Auri cul otemporal nerve (sensor y)

Inferior dental nerve (sensory)

Lingual nerve (sensory)

Nerve to mylohyoid and anterior belly of digastric (motor)

Auriculotemporal NerveAuriculotemporal Nerve

Auricu lo temporal NerveAuricu lo temporal Nerve

The auriculotemporal

nerve or nerves are

important because it is

the sensory nerve tothe TMJ and carriessecretomotor fibres

from the otic ganglion

to the parotid gland.


p. 1105

It leaves the main trunk ofthe mandibular nerve

shortly after the motor root

attaches to it, and passes

posteriorly towards themiddle meningeal artery.

It splits into two, the twobranches pass around the

middle meningeal artery

and circle it, and then theyjoin up again to form a

single branch.Modified from Grays Anatomy, Longmans, London, 38th Ed 1989

p. 1105

Auricu lotemporal NerveAuricu lotemporal Nerve


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p. 1105


It continues to runposteriorly, lying on the

tensor palati muscle,

and reaches the deep

aspect of the neck of themandible past which it

runs, between the boneand the

sphenomandibular

ligament.


p. 1105

Auricu lotemporal NerveAuricu lotemporal Nerve

It then curves around

behind the

temporomandibular jointwhich it supplies with

sensory fibres and runs

into the parotid salivarygland.

It gives off sensory and parasympathetic secretomotor fibres

acquired from the otic ganglion to the gland, and then curvesto run superiorly in the gland, and terminates in the superior

temporal branches, which supply common sensation to theskin and underlying structures in the posterior temple area and

the side of the scalp.


Inferior Dental NerveInferior Dental Nerve


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Modified from: Evers, H & Haegerstam, G. Introduction to

Local Anaesthesia, Mediglobe SA, Fribourg, 2nd Edition,

1990. P. 60


The inferior dental nerve, also

known as the inferior alveolar

nerve, is of great importance

because it provides thesensory nerve supply to the

pulps of the lower teeth.

To do so, it must enter thebody of the mandible.

It does this by passing through the

mandibular foramen on the internal

surface of the mandibular ramus,and running in the inferior dental

canal.



1990. P. 60


Initially, the nerve lies in the mandibular canal as a single trunk,

but soon divides into numerous smaller branches which form aplexus within the body of the mandible.


From Shigeru Tajiri, An Atlas of Anatomy of the Head and Neck, Aproman 1998

J.M. Sanchis, Miguel Penarrocha, and F. Soler, BifidMandibul ar Canal. J Oral Maxillofac Surg 61:422-424, 2003

Purpose: To determine the incidence and characteristics of bifidmandibular canals.

Methods:A retrospective study was performed using panoramicradiographs of 2012 patients subjected to dental treatment in the Dental

Clinic of the Valencia University Dental School (Valencia, Spain) between

1996 and 1999. The goal was to investigate the presence of doublemandibular canals.

Results: The extraoral panoramic radiographs revealed a total of 7 imagessuggestive of bifid canals. Mandibular computed tomography revealed the

existence of this anatomic variant in 2 of 3 patients. An analysis wasperformed on the incidence of this type of image in extraoral panoramic

radiography, its

possible interpretations, and the clinical implications of bifid mandibularcanals.

Conclusions: In this study, 0.35% of canals were bifid. All cases were inwomen.


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The nerve supplies

the pulps of the lower

teeth and theirperiodontal

ligaments, themandibular bone, and

the labial gingivaeand buccal gingivaeback about as far as

the second premolar.


Evers, H & Haegerstam, G. Introduction to Local Anaesthesia, Mediglobe SA, Fribourg, 2nd Edition, 1990. P. 85

While in the body of the

mandible, the nerve

splits into two branches.

Grays Anatomy, Longmans, London, 38 th Ed 1989 p. 1101


One of these continues

forwards in the body ofthe mandible to supply

labial gingivae and

pulps of the lower

anterior teeth, and it isknown as the incisive

nerve, or more

correctly, the incisiveplexus, because it hasceased to be a single

nerve trunk by thisstage.



The other exits themandible through a

small backwards-

directed foramen in the

external surface of thebody of the mandible

called the mental

foramen, usually found

between the roots of the

lower first and secondpermanent premolar

teeth.




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This branch is called themental nerve, and it

supplies common

sensation to the lower

lip and the front of thechin.



Nerve to the MylohyoidNerve to the Mylohyoid


The nerve to the mylohyoid

muscle and anterior belly of the

digastric branches off from theinferior dental nerve just before

it passes into the mandibular

foramen.

It is the only motor branch of

the posterior division, which is

why it supplies muscles insteadof other tissues.



1990. P. 60

Frommer and colleagues,

however, showed that

histologically, the mylohyoid

nerve contains both sensoryand motor nerve fibres.



1990. P. 60

Frommer, J, Mele, FA, & Monroe, CW. 1972.The possible role of the mylohyoid nerve in

mandibular posterior tooth sensation. J.

American Dental Assoc. 85, 113-117.



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Other studies have shown that

it may pass through small

lingual foramina in the mandible

with varying frequency in theanterior and premolar regions.



1990. P. 60

(Madeira, MC, Percinoto, C, & Silva, M. 1978.Clinical significance of supplementary

innervation of the lower incisor teeth: a

dissection study of the mylohyoid nerve. Oral

Surg. 46: 608-614.

Wilson, S, Johns, P, & Fuller, PM. 1984. The

inferior and mylohyoid nerves: an anatomic

study and relationship to local anaesthesia of

the lower anterior teeth. J American Dental

Assoc. 108: 350-352).


If the nerve branches from themain trunk of V3 high enough in

the infratemporal fossa to avoid

being bathed in anaesthetic

solution, then such patientsmay show signs of successful

anaesthesia and still show

sensitivity when dentalprocedures are undertaken.



1990. P. 60


Bennett and Townsend haveshown that the mean height of

the nerve branch in their series

of 6 dissections was 13.4 mmwith a maximum height of 20.7

mm, high enough in somecases to avoid anaesthesia with

a conventional block.



1990. P. 60

(Bennett S and Townsend G. Distribution of the

mylohyoid nerve: anatomical variability and

clinical implications. [online].Aust Endod J,

2001 Dec; 27 (3): 109-11).


This would seem to suggest a

possible accessory nerve

supply for anterior and premolar

mandibular teeth.

Additional anaesthesia of the

mylohyoid nerve can beobtained with a lingual

infiltration injection in the

premolar region.



1990. P. 60

(Bennett S and Townsend G. Distribution of the

mylohyoid nerve: anatomical variability and

clinical implications. [online].Aust Endod J,

2001 Dec; 27 (3): 109-11).



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Indeed, Sillanpaa and

colleagues anaesthetized the

mylohyoid nerves of volunteer

dental students and in 21%reported obtaining partial

anaesthesia of the lower teeth,

including the first mandibular

molar.



1990. P. 60

(Sillanpaa M, Vuori V & Lehtinen R. The

mylohyoid nerve and mandibular anaesthesia.

Int J Oral Maxillofac Surg. 1988 Jun; 17(3): 206-

207).


A specific cutaneous sensory

branch of this nerve supplying

an area of the chin has recentlybeen recognized.



1990. P. 60

(Hwang K, Han JY, Chung IH & Hwang SH.Cutaneous sensory branch of the mylohyoid

nerve. J Craniofac Surg. 2005 May; 16(3): 343-

345 (Discussion 346)).


Lingual NerveLingual Nerve


The lingual nerve leaves the

anterior aspect of the maintrunk of the posterior division

well above the mandibular

canal, and runs parallel to theinferior dental nerve for a

considerable distance.

It often goes numb when theinferior dental nerve is

anaesthetized.


Introduction to Local Anaesthesia, Mediglobe

SA, Fribourg, 2nd Edition, 1990. P. 60


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It comes to lie a little deeper

than the inferior dental nervethough, and does not run

into the mandible.


Instead, it curves gently above the mylohyoid muscle, passing

between the body of the mandible and the duct of the

submandibular gland to pass beneath the duct, rising again

medially to terminate in the substance of the anterior part of thetongue.

Netter, F.

1989,

Atlas of

Human

Anatomy,

Summit,

New

Jersey,

Ciba-

Geigy

Medical,

Plate 53.

The lingual nerve is the

major sensory nerve of

the anterior two-thirds ofthe tongue, and therefore

also carries the specialsensation of taste, as well

as common sensation.





It also supplies common

sensation to the tissues ofthe floor of the mouth, and

to the lingual gingival

tissues.

It must therefore be

anaesthetized if extractionof a lower tooth is required.






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It is commonly

anaesthetized along

with the inferior dental

nerve during theinferior dental nerve

block.

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

Anaesthesia in Dentistry, Astra Lkemedel

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




During its path as it

descends towards the

mylohyoid, it picks up a

small branch called thechorda tympani, whichcarries secretomotor

parasympathetic fibres

which it distributes to the

submandibular andsublingual salivary glands,as well as to minor salivary

glands in the floor of themouth.

These are preganglionicfibres initially, and they

synapse in the

submandibular ganglionwhich is located just inferior

to the lingual nerve close tothe submandibular gland.

The postganglionic fibres

pass to the submandibular

gland and some hook a ridewith the continuing lingual

nerve to reach thesublingual gland.



The lingual nerve can often provide accessory innervation to

anterior teeth, as can small branches from the ascendingbranch of the transverse cutaneous nerve of the neck.

Depositing a small amount of anaesthetic lingually (with

aspiration to avoid intravascular injection) will often solve theproblem.

Accessory Nerve Suppl iesAccessory Nerve Suppl ies


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McGeachie JK. Anatomy of the lingual nerve in relation to

possibl e damage during clinical procedures. Ann RAust ralas Col l Dent Surg. 2002 Oct;16:109-10.

Oral Health Centre of Western Australia. [email protected]

Damage to the lingual nerve, resulting in transient or permanentparaesthesia or anaesthesia, is a common undesirable complication of

surgical interventions to the lower third molar region. The anatomy of thenerve, as it travels from its origin high in the infra-temporal fossa, to thefloor of the mouth is quite variable. The most critical part of its course iswhere it enters the sublingual region just alongside the lingual alveolar

plate of the lower third molar.

A s igni ficant number of lingual n erves are lo cated above the alveo larbone in the gingival tis sues, or very close to the bone. Retraction of

the lingual mucosa can lead to lingual nerve trauma. There is no doubt thatthe lingual nerve is extremely vulnerable in this region and clinicians must

assume that it is closely adjacent to the lingual region of the lower thirdmolar, in all cases, in order to minimize possible damage.

Anterior Division of V3Anterior Division of V3

Anter ior Division of V3Anter ior Division of V3

The branches of the anterior division of themandibular nerve are:

Nerves to masseter (motor)

Nerves to temporalis (motor)

Nerve to lateral pterygoid (motor)

Nerve to medial pterygoid (motor)

Buccal nerve (Sensory)

Buccal NerveBuccal Nerve

The buccal nerve,

sometimes known as the

long buccal nerve (especially

in oral surgery), is thesource of common sensationto most of the cheek and the

buccal gingival tissues of the

lower posterior teeth.





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Buccal NerveBuccal Nerve

It must thereforealso be

anaesthetized if a

lower posteriortooth is to be

extracted.

Modified from: Haglund, J. &

Evers, H Local Anaesthesia in

Dentistry, Astra Lkemedel


Nerve Supply to Lower TeethNerve Supply to Lower Teeth

Pain sensation to the dental pulps of the lower teeth and

common sensation to buccal and labial gingival tissues is

supplied by the inferior dental nerve.

Therefore, any procedure that requires anaesthesia of thepulps of any lower tooth can be performed successfully if the

inferior dental nerve is blocked.

We try to anaesthetize

it just before it enters

the mandibularforamen, and this

ensures that toothpulps along the whole

of the anaesthetizedside remain numb.





Because there is some

crossing over of nervesupplies from the right

and left inferior dental

nerves near themidline, sometimes

infiltration anaesthesiais also required in this

area.


Modified from: Evers, H & Haegerstam,

G. Introduction to Local Anaesthesia,

Mediglobe SA, Fribourg, 2nd Edition,

1990. P. 87


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If anaesthesia is required for extraction, however, then the

nerve supply of the gingival tissues must also be

considered. The lingual nerve can be blocked to ensure

anaesthesia of the lingual gingivae.

Posteriorly, the buccal gingivae are supplied by the buccalnerve, and this must therefore also be anaesthetised for

extractions in this region.

For premolar and anterior teeth, the buccal and labial gingivae

are supplied by the inferior dental nerve, and they willtherefore have been successfully anaesthetised already by an

inferior dental nerve block.


Accessory Nerve SuppliesAccessory Nerve Supplies

Difficulty in anaesthetizing palatal teeth is most commonly due

to accessory innervation of those teeth by branches of thegreater palatine nerve or from the terminal branches of the long

sphenopalatine nerve.

Injection of a small amount of anaesthetic palatally will normallysecure anaesthesia. Other techniques such as intra-ligamental

or intraosseous injections may also be useful, as may newer

methods of anaesthetic delivery such as the wand.



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Difficulty in anaesthetizing mandibular teeth is most commonly

encountered in the molar area.

It it recognized that the long buccal nerve, lingual nerve,

mylohyoid nerve, and branches of the inferior dental nerve mayall contribute to such problems. In addition, sensory fibres from

the muscles of mastication may also provide an accessoryinnervation to these teeth.


Problems due to the long buccal nerve can be overcome by

administering a buccal block injection.


Those from the mylohyoid nerve or from accessory innervation

from muscles of mastication can usually be solved by injectinginto the floor of the mouth between the submandibular fold and

the mandible, taking care not to inject intravascularly, especially

into the facial artery. Inject through the mylohyoid muscle.


The cortical bone here is sometimes porous and thin enough to

allow diffusion of anaesthetic into the bone to anaesthetize

accessory nerve bundles from the muscles of mastication.


Copyright

A. Forrest2004


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The lingual nerve can often also provide accessory innervation

to anterior teeth, as can small branches from the ascendingbranch of the transverse cutaneous nerve of the neck.

Depositing a small amount of anaesthetic lingually (with

aspiration to avoid intravascular injection) will often solve theproblem.


Why is dental pulpal pain difficult to localize?

The pulp contains only pain fibres (A-delta and C fibres),therefore touch, temperature and pressure are only perceived

as pain. Any potentially damaging stimulus will cause

changes to the fluid in the dentinal tubules.

This pain is difficult to localize unless the inflammationextends to the periodontal ligament where additional sensory

receptors (pressure, proprioception) give further information.

In addition, the numerous pain fibres of the pulp converge onto

fewer fibres in the brainstem and information about the specific

tooth is lost.

Dental pain can be referred from one arch to the other arch,

but it never crosses the midline. It may also be referred to the

ear, neck etc.

Dental pain may sometimes be a pain referred to the teeth

from a non-odontogenic source e.g. sinuses, heart.

The only way to ensure accurate diagnosis of dental pain is bythorough history taking, examination and testing.

The following resources might be useful to you:

A good page on LA techniques is found at:

http://www.septodont.ca/Septodont/english/other/cea_di01.html

For a discussion on accessory foramina and innervation in themandible, see:

http://dmfr.birjournals.org/cgi/reprint/29/3/170.pdf

For a recent American discussion of LA in Dentistry, see:

http://www.cda.org/member/pubs/journal/jour0503/budenz.htm



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trigminal nerve v3 condensed grayscale slides

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