parotid and temporal region f1

8/2/2019 Parotid and Temporal Region f1

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hydrocephaly?

Hydrocephaly causes:

there is increased production of CSF

there is no drainage for CSF

or when the foramina of luschka is closed or occluded (it is a foramen in the

roof of the 4th ventricle where the CSF moves from the ventricles into the

subarachnoid space).

In the foramina of luschka is closurethe solvent is to make a foramen between the

brain and the subarachnoid space that's achieved by a procedure calledTHIRD

VENTRICULOSTOMY which means partial cut in the 3rd ventricle because it's

the easiest place and closest space to reach the endoscope into it.

firstly open a bare hole in the skull anterior to the coronal suture of the skull, then

insert the endoscope inside then u can see the following: inter ventricular

foramen (the foramen between the lateral ventricles and the third ventricle),

corroid plexus (the part that produces CSF), the floor of the third ventricle, fluid

movement in the 3rd ventricle, the basilar artery (formed by the joining of the 2

vertebral arteries)

when we reach the floor of the 3rd ventricle we burn itby the very hot tip of the

endoscope to penetrate it to make an opening to the subarachnoid space, then

we noticed the movement of the CSF from inside the ventricles to the outside.

to watch the video -->http://www.youtube.com/watch?v=bjGVXYH9mZg

In case there is increase production or no drainage of CFS without closure of the

foramina of luschka so the fluid go easily from ventricles and the subarachnoid

space this time we have to do a shunt "" we call it THE CSF SHUNT.

Everything is explained here --

>http://www.youtube.com/watch?v=Qmym2iFVNw8

___________________________________________________________________
http://www.youtube.com/watch?v=bjGVXYH9mZghttp://www.youtube.com/watch?v=bjGVXYH9mZghttp://www.youtube.com/watch?v=Qmym2iFVNw8http://www.youtube.com/watch?v=Qmym2iFVNw8http://www.youtube.com/watch?v=Qmym2iFVNw8http://www.youtube.com/watch?v=bjGVXYH9mZg


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Parotid & Temporal Regions

As u know when we study any region we have to study the borders and the

contents (5 things: organs, veins, arteries, nerves and lymph nodes).

The Parotid Region

Location:

extends between the ramous of the mandible anteriorly and the mastoid process

posteriorly ,placing your index in the mandible and the thumb on the mastoid

process it is the area in between and below the auricle , we call it by the parotid

region because it contains the parotid gland (the largest slivery gland)

Contains:

*Parotid Gland&Structures Inside it or within the gland tissue.

*VAN (facial n., ECA, retro mandibular vein).

We will classify them from lateral to medial or superficial to deep:

1. Superficial:

The most superficial is the Facial n.terminates there to provide five branches to

the muscles of facial expression temporal, zygomatic, buccal, mandibular and

cervical branches you can see them within the parotid tissue.

2. Middle:

Deep to the nerve you will find theRetromandibular V. the vein behind the

mandible and the terminal branches of the vein forming it superficial temporal

vein and maxillary vein, the terminal part of superficial temporal and maxillary

veins enters the parotid gland and within the parotid tissue they unite to form

retromandibular v.

3. Deep:


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the deepest structure always is the artery you will find theECA(external carotid

artery) with its terminations it terminates there within the parotid tissue behind

the neck of themandible into two main arteries:maxillary a. and superficial

temporal a., the beginning part of them located within the parotid tissue.

4. Parotid Lymph Node:

Distributed within& on the gland, drain into DCLN Deep Cervical Lymph

Nodes, all of the lymph nodes in the facial area in the head drain into theDCLN

which unite with IJV Internal Jugular Vein within the carotid sheet.

If we have a cross section of the parotid tissue and flip it to look from above wewill have the following view:

1-Muscles of the wall of the pharynx get into the pharyngeal area and oral

cavity.


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2- The Skin.

3-Mastoid process.

4- Cross section of the ramous of the mandible so between C3 and C4 we have

the parotid region.

5-Fibrous capsule (facial capsule) very strong fibrous sheet covers the whole

parotid gland originating from investing layer of deep cervical fascia.

6-Facial n. the most superficial structure passing within the gland.

7- Retromandibular v. after the nerve.

8- ECA External Carotid Artery the most deepest one, not the Common nor the

Internal because both are within the carotid sheet.

9- Carotid sheet with contents ICA Internal Carotid Artery.

10- Parotid lymph nodes groups of lymph nodes.

distributed within and on the surface of the gland

The parotid gland :

It is the largest slivery gland wedge (triangular ) shape gland anatomically

speaking, its base inferior-posteriorly to the zygomatic arch while the apex is

located inferiorly behind the neck of the mandible.The parotid gland usually

secrets apure serous saliva.

We have two types of saliva: mucous and serous,serous is more watery and the

mucous is more viscous (). It is covered by a connective tissue called parotidcapsule which comes from the investing layer of deep cervical fascia.

Homework: what is the difference in function between mucous and serous saliva?

Processes of the parotid gland:

So till now we spoke about all the contents except the parotid gland those are : facial n., retromandibular

v., ECA and parotid lymph nodes.


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Process is an elevation or extension, the parotid region is between the ramous

and the mastoid process and below the auricle (the external auditory meatus)

until the angle of the mandible, but if there is any part if the parotid gland tissue

that extend over this region we will refer to it as a process of the parotid gland so

its part of the gland tissue but not located in its region ( ) crossing the

border of this region.

The process: an extension from the parotid gland tissue into certain regions

outside of the parotid region.

There are three processes:1-glenoid process, 2-pterygoid process,3-facial process;

each one indicating to each way they go:

1- Glenoid Process:

An extension of the parotid tissue into the Glenoid cavity (or the glenoid fossa, it

is the same as the mandibular fossa in the skull when u look to the skull in the

temporal bone there is a depression from the TMJ we call it the mandibular fossa)

so behind the TMJ in the posterior part of the mandibular fossa (glenoid fossa) u

will see part of the parotid gland which is the glenoid process.

So its the process that extends upward into the posterior part of the

mandibular fossa.

2- Pterygoid Process:

It will go forward and deep to the mandible between the ramous

of the mandible and the medial pterygoid muscle.

Now we have to speak about medial and lateral pterygoid

muscles >> you remember we have four muscles of masticationthose are the temporalis and masseter from outside of the

mandible and from inside of the mandible we have another two

we call them the lateral and medial pterygoid muscles.

Summury:

So both originate from

the lateral pterygoid

plate, no one of them

from the medial plate;

but the one from the

lateral surface of the

lateral pterygoid plate is

the lateral pterygoid

and the one from the

medial surface of the

lateral pterygoid plate is

called medial pterigoid,

cuz where they originate

fom.


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The horizontal one is the lateral and the vertical one is the

medial pterygoid, we call them medial and lateral because both

of them originates from the lateral pterygoid plate, one from the

lateral surface of the lateral pterygoid plate into the neck of the

mandible which is the lateral pterygoid muscle, but from the

medial surface of the lateral pterygoid plate to the angle of the

mandible medially this one is the medial pterygoid muscle.

There is another muscle of mastication insert on the lateral aspect (outside) of the

neck of the mandible it is the masseter,as a result the ramous of the mandible

issandwiched between two muscles of mastication from outside is the masseter

from inside the medial pterygoid muscle, Behind the ramous more superficial

should be the parotid gland because it located the posterior border of the ramousand the mastoid process.

Part of the glands tissue will extends into two different ways, the first part go

deeply into the space between the ramous and the medial pterygoidwhich is the

pterygoid process, and the second part go outside or superficially too sleep over

the masseter muscle which is the facial process.

3- Facial Process: Extends forward superficially from the parotid

gland over the masseter muscle sleeps anterior to the masseter

muscle from outside.

Sometimes part of the facial process get to separate completely from the parotid

tissue as a small piece by itself which is the accessory part if the parotid gland, it

is not always present in all individuals put if its present its a small branch of the

facial process that get separate completely.


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Relations to Parotid Gland:

Superficial (lat.):Firstly the parotid gland is covered by skin then the superficial fascia then the

deep fascia (investing layer make the parotid capsule) within the superficial fascia

there is an important nerve the great auricular nerve (C2,C3) if u remember it

gives sensation to the skin over the angle of the mandible the parotid region and

the lower part of the auricle (lobule).

Superior:Superiorly there are the external auditory meatus (EAM) and the TM joint.

Deep Relations (Medial):Deep relations means the medial aspect or where the parotid is resting we refer

to these relation as the parotid bed because they representing where the parotid

tissue is resting and because its pyramidal shape there will be anterior and

posterior medial there is nothing exactly medial:

Antero-medial:

We can see the masseter muscle and part of the ramous and part of the TM joint

(specially the lower part of the capsule)

Summery :

there are three process from the parotid

gland :

1- Glenoid : upward into the mandibular

fossa

2- pterygoid : forward between the

ramous and medial pterygoid muscle

3- facial: forward too but superficial

over the masseter muscle

** we can find accessory part

sometimes from the parotid gland, its

usually extension from the facial

process.


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Posterio-medial:

We can see the carotid sheath and its contents, the styloid process and related

muscles (styloglossus, stylohyoid ,stylopharyngous) an d the mastoid process with

muscles related (from outside the SCM & from inside the posterior belly ofdigastric).

Parotid Duct (Stinsons duct)

They named it according to the person who described itStinsonsduct the

submandibular duct we call itWhartons duct extends from the facial process of

the parotid and go superiorly then horizontally superficial to the masseter muscle

and inferior to the zygomatic arch, at the anterior border of the masseter it turns

medially passing throw the cheek penetrating the buccinators muscle to open into

the oral cavity opposite to the upper second molar in most individuals so

sometimes you can find it opening opposite to the upper second premolar! Or

upper first molar but most commonly speaking upper second molar.

There is an accessory duct sometimes if you have an accessory part the part

that originate from the facial process so because its independent it has its own
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small duct which drain into the main duct (Stinsons duct) so we call it accessory

parotid duct.

For Blood Supply, Innervation &Lymph Drainage of Parotid Gland:

The external carotid artery (ECA) will provide blood supply to the parotid tissue,

the vein is the retromandibular vein so it will provide the drainage to it , the

sensation over the parotid gland come from the great auricular nerve and it takes

from the glossopharyngeal nerve (IX) for secretion which isthe lesser petrosal

nervewe will talk about it.

Clinical: Mumps

It is an acute viral infection to the parotid gland that cause swilling and pain, so ifthere is an inflammation there is edema and fluid accumulation and the parotid is

covered by a strong capsule (parotid capsule) so what happening is this fluid

accumulation enlarged an the but the swilling is limited by the capsule which

leads to severe pressure and stretch on the parotid capsule itself will produce the

pain feeling and also this will press on the nerve inside the parotid capsule the

facial nerve leading to a parasthesia (partial paralysis) in the muscles of facial

expirations,so the pain because of the swilling of the tight parotid fascia.

The pain is getting worst during chewing because when you open your mouth the

ramous of the mandible go posteriorly to make the space of the parotid gland

smaller than it is so this will increase the pressure by compressing it between the

ramous of the mandible and the mastoid process, so its very hard to chew in this

case.

The viral infection may reach to the parotid duct through the parotid tissue if so

you will see it more reddish in color and swilling.


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Parotidectomy

It is a common procedure in Oral and maxillofacial surgery mainly it is a surgical

removal of the parotid gland its most common cause is the cancer because 80% of

the tumors of the salivary gland affect the parotid gland because its the largestone.

The most and first important step for any surgeon oral surgeon or maxillofacial

surgeon once he removes the parotid is to preserve the vital structures within the

parotid tissue those are the facial nerve, ECA and the retromandibular vein its

Unacceptable to get injuryto any of those if you cut part of the facial nerve the

patient will have facial palsy bells palsy , and the ECA will lead to severe

bleeding because its very large artery and the same for the retromandibular vein.

So the first step you have to identify those structures by cutting the tissue to find

them, secondly; you have to isolate () them, thirdly; you have to preserve

) them after that you can start removing the tissue of that gland,, so its )

step by step not just cutting the parotid simply!!Thats totally huge mistake!

The Temporal Region

the temporal region its the region that sets on the side of the head over the

temporal bone or the temple.

Boundaries:

Superiorly and posteriorly the superior temporal line, there are two linear

elevation at the side of the skull we refer to them as the superior temporal lineand the inferior temporal line, when we have an elevation that means there is an

attachment of a muscle, ligament or fascia, so what attaching to the inferior one

is the temporalis muscle (the largest muscle of mastication), and the superior line

attachment is a homework???


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So superiorly demarcating of the temporal region is the superior temporal

line.Anteriorly it demarcating by the frontal process of zygomatic bone, and

inferiorly by the zygomatic arch.

Contents of Temporal Region:

1-Temporalis muscle:Its the largest muscle of mastication, originates from the whole floor of the

temporal region area of the temporal fossa then it diverge all the way to

insert by a small tendon into the coronoid process of the mandible and the

anterior border of the ramous.The muscles fibers of the anterior half are


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vertical so when they contract they elevate the mandible to close the mouth,

but the posterior half fibers are more horizontal so when the contract they

retrode (moving backward) the mandible retraction. So it has two functions,

elevation (the anterior part of it) and retraction (the posterior part of it)

2-Deep temporal arteries and nerves:The innervation: any muscle of mastication innervated by the mandibular of

trigeminal so the innervation of this muscle come from the mandibular of

trigeminal and because it is a very large muscle and has two parts each one

has a different function its got innervation by two nerves we name them the

temporal nerves coming from the anterior division of the mandibular nerve if

you still remember the story of mandibular nerve and they pass deep to thetemporalis muscle between temporalis and the bone,so we have two nerves:

the anterior deep temporal nerve to the anterior half and the posterior deep

temporal nerve to the posterior half.

The arteries: the same as the nerves because its too large it has two deep

temporal arteries, the external carotid artery terminate by the superficial

temporal a. and the maxillary a. as the maxillary passing it gives a branch to

the posterior and a branch to the anterior which are the anterior and posterior

deep temporal arteries so their origin from the maxillary a.

3-Temporal fascia:Is the deep fascia covering the muscle its usually attached as continuation of

the epicranialaponeurosislaterally.

4- Superficial temporal artery and vein:They are the artery and vein over the temporal region superficially where youfeel the bulls, both of them pass posterior to the TMJ.


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5- Auriculo-temporal nerve:It passes posterior to the superficial temporal artery and vein, originating from

the posterior division of mandibular nerve the posterior division of

mandibular has three branches sensory (lingual, inferior alveolar and auriculo-temporal) and one is motor (nerve to mylohyoid), so it gives sensation over

the temporal region.

AND THATS ALL

*****

This is a true real Question from the US MLE , thats howthey ask you they give a clinical condition and give anatomical and physiologicalquestions, they dont ask like what we examine you just a question and whats

the answer!! So you have to read the scenario then you can answer the

questions whether they related or notCLINICAL CASE

A 44-year-old female with swelling over the parotid gland on the right side

not bilateral visited you in the clinic. She stated that she first noticed the

swelling 3 months previouslyso its not painful,and since that time it hadrapidly increase in size. Recently, she noticed that her right side of her face felt

weakand she could no longer whistle for her cat.

On examination, a hard swellingits not edematous so its not inflammation,

the ridged swelling is more dangerous refer to a tumordeeply attached to the

parotid gland was identified. On testing the facial muscles, it was found that

the muscles on right side were weaker than those on left side. Before starting

any further management, answer the following questions?

Q1. What is (are) the cutaneous innervation of the skin over the parotid region?

Great auricular nerve, Cutaneous means skin and sensory.

Q2. What muscles control her whistling?

Buccinator& orbicularis oris , those are the two main ones.


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Q3. What is the connection between the right side facial weakness & the

parotid swelling?

The swelling is pressuring over the facial nerve.

Q4. What is the diagnosis?Parotid tumor, because its ridged and painless.

Q5. What is the treatment?

Parotidectomy, removal of the parotid gland.

Q6. What is (are) the structure(s) that may be endangered of such kind of

treatment?

Facial nerve, ECA and retromandibular vein.

THE HAPPY ENDDone by: Baraah Al-Salamat

Edited by: C.W.T

parotid and temporal region f1

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