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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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