Parotid Gland Viiiiiiiiiip

8/4/2019 Parotid Gland Viiiiiiiiiip

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The Parotid Region of the Face

The parotid region is actually part of the neck but it extends into the facial region as well.

It also must be studied before the infratemporal region can be examined. We will

examine the parotid region from superficial to deep pointing out the gland itself and thestructures running through it.

The parotid gland is asuperficial structurelocated in the upper neckabove the posterior bellyof the digastric muscle. Itis a salivary gland thathas a large duct (pd)which crosses the

masseter muscle to piercethe buccinator muscleopposite the upper 2ndmolar tooth. The duct canfrequently be rolledbetween the finger andthe masseter muscle. Theskin overlying the lowerpole of the gland issupplied by the greaterauricular nerve (ga), a

branch of the cervicalplexus. You have alreadyidentified the branches ofthe facial nerve appearingat the upper and anterioredges of the gland(yellow).


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If the parotid gland iscarefully removed, youcan identify the structureslocated within it. The firstplane is the venous plane

and consists of theretromandibular vein (rm)and its tributaries andbranches:

st--superficialtemporal

rm--retromandibularvein

m--maxillary vein

ad--anterior division f--facial cf--common facial pd--posterior

division pa--posterior

auricular ej--external jugular

The common facial veinempties into the internal

jugular vein and theexternal jugular into thesubclavian vein near its

junction with the internaljugular.

When the venous plane isremoved we reach theimportant nervous plane.The importance of thisplane is the presence ofthe facial (VII) nerve. The

facial nerve leaves theskull through thestylomastoid foramen andimmediately enters thedeep part of the parotidgland where it gives off itsbranches:


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posterior auricular(pa)

motor branch toposterior belly of

digastric (db) temporal branch (t) zygomatic branch

(z) buccal branches (b) mandibular branch

(m) cervical branch (c)

Deep to the nerves liesthe arterial plane which

includes terminal partsof the external carotidartery and its branches:

external carotidartery (EC)

occipital artery (oc) maxillary artery (m) transverse facial

artery (tf) superficial temporal

artery

The deepest part of theparotid region is theparotid bed and housesthe deep part of the glandwhich fills the small spacebetween the neck of thecondyle of the mandible(nc) and the mastoidprocess (m). Otherstructures forming thefloor of this space are the:

styloid process (sp) stylohyoid muscle

(sh)


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stylopharyngeusmuscle (sph)

posterior belly ofthe digastricmuscle (pbd)

The gland becomesinfected and swollen inmumps. If you have hadthe mumps, you willrealize just how difficult itis to open your mouth.Now, you can see whythis is so. When you openthe mouth, you narrow theparotid bed space and

compress the deepparotid gland between theneck of the condyle andthe mastoid process.

The Infratemporal Fossa and Muscles of Mastication

The infratemporal fossa is a small space between the ramus of the mandible and the

lateral pterygoid plate of the sphenoid. On a skull, it is big enough for maybe 1 1/2

fingers but it has many things in it. Following is a tabulation of the infratemporal fossa

and all of its contents.The lateral wall ofthe infratemporal

fossa is noted in the

1st image and

consists of the

ramus (4)o coron

oid

proce

ss (1)o head

of

condy

le (2)

o neck

of

condy

Medial wall:lateral pterygoid plate (1)

Roof;

greater wing of sphenoid (3)

includes foramen ovale &foramen

spinosum

Posteriorly:styloid process (4)


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le (3)

body (5)

angle (6)

There are four

muscles of

mastication on each

side that control themovement of the

mandible:

masseter

medial

pterygoid lateral

pterygoid

temporalis

The lateral pterygoid

is the main musclethat opens the

mouth. It is helped

from gravity and a

couple of neck

muscles. It opens theaw by pulling

forward on the neckof the mandible and

causing the jaw to

drop.


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The artery entering theinfratemporal fossa is themaxillary branch of the

external carotid artery. Ascan be seen, it has manybranches (11 in all). You willprobably not be responsiblefor all of them but I haveincluded them all forcompleteness.

Maxillary artery

o deep auricular (da)

o anterior tympanic (at)o middle meningeal

(mm)o accessory middle

meningeal (amm)o inferior alveolar (ia)o buccal (b)o deep temporal (dt)o posterior superior

alveolar (psa)o descending palatine

(dp)o infraorbital (io)o sphenopalatine (sp)

External carotid artery (ec)

o occipital (oc)o transverse facial (tf)o superficial temporal

(st)

The sphenopalatine anddescending palatine arteriespass through a small spacebetween the pterygoidprocess of the sphenoid andthe maxilla, thepterygomaxillary fissure.


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The mandibular nerve (V3) is thenerve of the infratemporal fossaand is responsible for supplyingthe muscles of mastication plustwo tensor muscles: 1) tensor

palati and 2) tensor tympani. Thebranches are as follows:

deep temporal (dt) auriculotemporal (at) inferior alveolar (ia)

o nerve to themylohyoid (nmh)

lingual (l) buccal (b) branches to lateral pterygoid

(not labeled)

Not shown:

meningeal branch nerve to masseter

The Temporomandibular Joint (TMJ)

e temporomandibular joint (tmj) is a synovial type joint

parated by an interarticular disc. The disc splits the joint into two

parate joints. The upper joint (ujc) is between the mandibular

ticular) fossa of the temporal bone and the articular disk andovides a sliding motion when the lateral pterygoid contracts and

lls the condyle and disc forward.

e lower joint (ljc) is between the articular disc and the head ofe condyle of the mandible. The action here is a hinge-like action,

which the mandible drops, thereby opening the mouth.

hen dentition or muscle action is not in proper alignment, the

nt can be secondarily affected and pain can ensue. This is TMJease and requires dental specialists to correct the problem.


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Table of Muscles

Muscle Origin Insertion ActionNerv

Supp

asseter zygomatic arch ramus & angle ofmandible closes mouth musculabranch (

edialerygoid

medial surface of lateralpterygoid plate and maxillarytuberosity

medial surface oframus and angle ofmandible

closes mouth and helpsprotrude mandible

musculabranch (

eralerygoid

upper head: greater wing ofsphenoidlower head: lateral surface oflateral pterygoid plate

upper head: articulardisclower head: neck ofcondyle

open and protrudesmandible, moves mandibleside to side

musculabranch (

mporalis temporal fossa

coronoid process and

anterior border oframus

closes and retracts

mandible

muscula

branch (

Summary of Items in This Lesson

BonesMandiblebodyangleramus

condyleheadneckcoronoid processmental foramen

Temporal boneMastoid processstyloid processstylomastoid foramenmandibular (or articular) fossa

Temporomandibular jointarticular discSphenoid bonegreater wingforamen ovaleforamen spinosumpterygoid processlateral pterygoid plate

Nerves (contd.)

Facial (VII)posterior auriculartympanic

zygomaticbuccalmandibularcervicalbranch to posterior belly of the digastric

Arteries

external carotidoccipitalmaxillary

inferior alveolarmiddle meningealaccessory middle meningeal (if present)deep temporalbuccalposterior superior alveolar branchesdescending palatinesphenopalatine


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Pterygomaxillary fissurePosterior surface of maxillaposterior superior alevolar foramina

Muscles

MasseterMedial pterygoidLateral pterygoidupper bellylower bellyTemporalis

Nerves

Mandibular division of trigeminal (V3)

auriculotemporaldeep temporalinferior alveolarnerve to mylohyoidlingualchorda tympanibuccalmuscular branchesmuscles of masticationtensor palatitensor tympani

infraorbitaltransverse facialsuperficial temporal

Veins

superficial temporalmaxillaryretromandibularanterior divisionfacialcommon facialposterior divisionposterior auricularexternal jugular

Viscera

parotid glandparotid duct

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Parotid Gland Viiiiiiiiiip

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