lymphatics slides(1)

7/27/2019 Lymphatics Slides(1)

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Lymphatic DrainageLymphatic Drainage

Alex Forrest

Associate Professor of Forensic OdontologyForensic Science Research & Innovation Centre, Griffith University

Consultant Forensic Odontologist,

Queensland Health Forensic and Scientific Services,

39 Kessels Rd, Coopers Plains, Queensland, Australia 4108

Oral Biology


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COMMONWEALTH OF AUSTRALIA

Copyright Regulations 1968

WARNING

This material has been reproduced and communicated to you by, or onbehalf of, Griffith University, pursuant to Part VB of The Copyright Act 1968

(The Act; a copy of the Act is available at SCALEPlus, the legal

information retrieval system owned by the Australian Attorney Generals

Department, at http://scaleplus.law.gov.au).

The material in this communication may be subject to copyright under the

Act. Any further reproduction or communication of this material by you may

be the subject of Copyright Protection under the Act.

Information or excerpts from this material may be used for the purposes of

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may only be reproduced as permitted under the Act.

Do not remove this notice


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Learning GoalsLearning Goals

On completion of this topic you should be able to describe

the general plan of the lymphatic drainage of the head

and neck.

You should be able to describe the positions of all the

major groups of lymph nodes.


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You should be able to describe and demonstrate the

ability to assess clinically the spread of infection in the

head and neck using the major lymph node groups.

You should demonstrate an understanding of the role

played by the lymphatic system in controlling and

directing the spread of infection and certain neoplasia

in the head and neck.


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LymphaticsLymphatics

The lymphatic system is concerned with the removal and

return to the blood system of tissue fluid not reabsorbedinto the blood capillaries during circulation, with the

absorption of fat from the small intestine, and most

importantly, with immunity.


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It consists of lymphatic capillaries and vessels, lymph

nodes, organs such as the thymus, spleen and bonemarrow, and with masses of lymphatic tissue in the

walls of the alimentary tract, together with circulating

cells.


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In our discussion of the lymphatics in this session, we

will restrict ourselves to a discussion of the structural

components of the lymphatic system and the variousgroups of lymph nodes and lymphatic capillaries and

vessels in the head and neck, and consider their

importance in the spread of infection and in clinical

diagnosis.


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Vascular SystemVascular System

Recall that the blood vascular system is a body system

that deals with two of the body's most important

functions: transport and protection.

It comprises the blood system, the lymphatic system,

and the interstitial fluid. Each of these is related to the

other, and their functions are closely allied as a result.


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Vascular SystemVascular System

The blood system acts as the transport system for the

body.The lymphatic system is the body's protective system.

Interstitial fluid is the contact that each individual cell has

with the fluid system of the body.


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Fluid MovementFluid Movement

The heart acts as

the fluid pump

within the body.It pumps blood into

arteries, and

receives blood from

veins.

http://www.mhhe.com/biosci/ap/dynamichuman2/content/gifs/0136B.gif


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On the right side, blood is sent into the pulmonary circuit. The

pulmonary artery carries deoxygenated blood to the lungs, and

the pulmonary vein returns oxygenated blood to the left side of

the heart.

http://www.mhhe.com/biosci/ap/dynamichuman2/content/gifs

/0140.gif


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The left ventricle of the heart pumps blood into the systemic

circuit, though which it flows eventually back to the right atrium

before revisiting the pulmonary circuit again.

http://www.mhhe.com/biosci/ap/dynamichuman2/content/gifs

/0140.gif


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Blood leaving the heart initially

flows through large arteries. Asthese arteries become more distant

from the heart, they subdivide,

becoming smaller vessels known

as arterioles.

Arteries and arterioles have

significant amounts of smooth

muscle in their walls, and this helpsmaintain blood pressure, and

absorbs some of the pumping force

of the heart.http://www.lab.anhb.uwa.edu.au/mb140/CorePage

s/Vascular/Vascular.htm


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Finally blood flows into smaller

vessels still, known as

capillaries.

Capillaries are incredibly

numerous, but are small in

cross-section, and are quite

permeable to a number ofsubstances including fluid from

the blood plasma.http://www.lab.anhb.uwa.edu.au/mb140/CorePage

s/Vascular/Vascular.htm


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Due to the blood pressure in the

initial part of the capillary, some

of the plasma is filtered through

the vessel wall and emergesfrom the capillary.

This is the source of the

interstitial fluid, the fluid that liesbetween the cells of the body.

http://www.chelationtherapyonline.com/articles/im

ages/bloodvessels_4.gif


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You may think of interstitial fluid as resulting in some

respects from the natural leakiness of the capillaries.Within the interstitial fluid, nutrients and gases are carried

to every cell of the body, and waste products are

removed.


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As the blood pressure fallsalong the length of the

capillary, it becomes

comparable with the

osmotic force exerted by theconcentration of large

molecules remaining in the

capillary lumen that did not

escape into the surroundingtissues. http://www.chelationtherapyonline.com/article

s/images/bloodvessels_4.gif


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As we move further

along the capillary, and

the blood pressure

drops still further, theosmotic force begins to

dominate, setting up an

osmotic gradient that

favours the return of theinterstitial fluid back into

the capillary.

Van de Graff, K. Human Anatomy, Wm. C. Brown Iowa, 2nd Ed. P532


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Approximately 80% to 90% of interstitial fluid is reabsorbed

back into the capillaries in this way.

http://training.seer.cancer.gov/module_anatomy/unit8_2_lymph_compo.html


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http://training.seer.cancer.gov/module_anatomy/unit8_2_lymph_compo.html

The remainder would waterlog the tissues, however, if it were

allowed to remain, so instead it is gathered up into small

vessels known as lymphatic capillaries, and channelled into

the lymphatic system.


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Here, it passes into

lymphatic vessels, during

its passage along which it

will pass through lymphnodes.

The lymph nodes play a

role in controlling thespread of infection and in

fighting it.

Van de Graff, K. Human Anatomy, Wm. C. Brown Iowa, 2nd

Ed. P 532


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Eventually, all this lymph

fluid is returned to the

blood system through two

large lymphatic vessels,the right lymphatic duct

and the thoracic duct,

which drain into veins in

the neck.

From Grays Anatomy, Longman, London, 35th Ed 1973p.727.


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The remainder of the blood

returns to the heart throughlarger vessels, venules,

which lead to veins, and

these, in turn, return to the

heart.

Van de Graff, K. Human Anatomy, Wm. C. Brown Iowa, 2nd

Ed. P 532


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Now that we can see the broad relationship between the

three types of fluid, blood, lymph and interstitial fluid, andhow the interstitial fluid and lymph are formed, let us

examine the components of the system more closely.


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Lymphatic CapillariesLymphatic Capillaries

Unlike the capillaries of the blood system, which bridge

between the arterial part and the venous part of the

circulation, there is no arterial part to the lymphatic

system.

It simply begins in the tissues, wherever excess tissue

fluid collects from blood capillaries, as a system of blind

lymphatic capillaries.


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Lymphatic capillaries aretiny thin-walled vessels

that begin as blind tubes

in the spaces between

cells in most tissues ofthe body except in

cartilage and the central

nervous system, the

epidermis including thehair and nails, cornea of

the eye, and also bone

marrow.www.anatomy.dal.ca/html/Human%20Histology/DHD/Lab2/

4_lh.JPG


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Basically, anywhere that there is circulation, there are also

lymphatic capillaries.

They are not therefore found in the avascular tissues such asthose we listed above.

Tissue fluid in the brain and spinal cord drains into the

cerebrospinal fluid through spaces around the blood vessels.


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In structure, lymph

capillaries are mostsimilar to blood

capillaries, but differ in

some respects.

www.anatomy.dal.ca/html/Human%20Histology/DHD/Lab2/4_lh.JPG


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Lymph capillaries are lined by

endothelial cells like bloodcapillaries, but in lymphatic

capillaries, the endothelial

cells overlap each other.

http://www.bmb.psu.edu/courses/bisci004a/immune/lympi

ntak.jpg


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This is important, because

when pressure from the

accumulating tissue fluid fromoutside the capillary pushes

on its wall, the flap of

endothelial cell beneath the

overlap swings inwards to letthe fluid into the vessel. http://www.jdaross.mcmail.com/images/lympha

tic.gif


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Once the fluid is in the lumen,

then it cannot escape again,because it simply pushes this

flap closed again and is

prevented from getting back

out.

Because of this structure,

lymphatic capillaries are more

permeable than bloodcapillaries, and substances of

http://www.jdaross.mcmail.com/images/lympha

tic.gif

large molecular size, and even particles such as cell debris

and micro-organisms can be accommodated.


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They also have larger, moreirregular lumens which are

capable of holding larger

particles in their contents.

They are very hard to see in

microscopic sections because

they tend to collapse when

they are empty.

http://www.bmb.psu.edu/courses/bisci004a/immune/lympi

ntak.jpg


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Lymphatic capillaries also

possess valves which permit

the lymphatic fluid to travel in

one direction only.This is important, because it

ensures that fluids and

materials collected in a

lymphatic capillary are

directed through lymph nodes.http://www.jdaross.mcmail.com/images/lympha

tic.gif


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These lymphatic capillaries form networks that eventually join

together to form larger trunks, which have a structure similar

to veins, but are thinner with less-well defined tunic layers.

Along these larger vessels lie lymph nodes.Lymph from most parts of the body is forced to pass through

one or more lymph nodes on its way back to the venous

circulation, with the exception of the lymph from the thyroid

gland and the oesophagus, which drains directly into the

thoracic duct.


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Lymph VesselsLymph Vessels

Eventually, lymph vessels drain into either the thoracic duct or

the right lymphatic duct.All of the lymphatic vessels of the body drain into the thoracic

duct except for those of the right side of the head, the right

upper limb, and the right neck and the right side of the thorax.


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The thoracic duct drains into the

junction between the left internaljugular vein and the left subclavian

vein.

All the tissues of the right side of

the head, the right upper limb, and

the right neck and thorax drain into

the right lymphatic duct which

drains in turn into the junctionbetween the right internal jugular

vein and the right subclavian vein.

From Grays Anatomy, Longman, London, 35th Ed 1973p. 727


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Larger lymphatic vessels also possess valves, which onceagain forces the lymph to travel away from the tissues and

towards the venous circulation in one direction only.


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Lymphatic NodulesLymphatic Nodules

Throughout the loose connective tissues of the body, small

nodules of lymphatic tissue can be found. These are smallishmasses, perhaps 1 mm or so in diameter, and they occur

particularly in the connective tissue beneath mucous

membranes.


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In the head and neck, they are particularly noticeable around

the posterior part of the oral and nasal cavities.

Elsewhere in the body, we find them in the walls of the

intestines, around the anus, and in relation to the urinary tract.


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They are distributed strategically so as to protect underlying

tissues that may be at risk of penetration by microorganismsfrom the digestive, respiratory and urinary tubes, all of which

have surfaces that lie outside the body, and which may

therefore harbour dangerous bacteria and viruses.


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If you examine such a lymph nodule with a microscope, you

notice that it is packed with lymphocytes, but unlike the lymph

nodes, the lymph nodules do not connect to lymph vessels.

An Atlas of Human Histology, Di Fiore M. Lea & Febiger, Philadelphia, 1st

Edition 1961, p. 113.


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Sometimes, observation with the microscope will reveal centres

where many immature lymphocytes are busily developing in

response to some immune challenge that requires cells that

can respond to a specific agent.

An Atlas of Human Histology, Di Fiore M. Lea & Febiger, Philadelphia, 1st Edition 1961, p. 113.


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Such areas are known as germinal centres.

An Atlas of Human Histology, Di Fiore M. Lea & Febiger, Philadelphia, 1st Edition 1961, p. 113.


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While most lymphnodules are smallish

and occur as solitary

structures, in some

areas they are found

as large clusters.

Some of these we are

already familiar with,

such as the tonsils.

Copyright University of Queensland School of Dentistry


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Indeed, the tonsils form a kind of ring around the entry to the

oropharynx and nasopharynx, made up of the single

pharyngeal tonsil (adenoid), the two palatine tonsils, and thelingual tonsil.

This ring is known as Waldeyer's Lymphatic Ring, after the

worker who first described it.


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Lymph NodesLymph Nodes

Lymph nodes are small,

bean shaped masses oflymphatic tissue of

varying size.

http://www.acm.uiuc.edu/sigbio/project/updated-

lymphatic/lymph7.html


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The node is enclosed in a

strong fibroelastic

capsule, and extensions

of this capsule run intothe node, forming

partitions that partially

divide the node into

several incomplete

compartments.

Van de Graff, K. Human Anatomy, Wm. C. Brown, Iowa, 2nd

Ed. P 534


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Lymph vessels that

approach a lymph

node, carrying theirone-way load of

lymph, divide up into a

number of branches.

http://www.acm.uiuc.edu/sigbio/project/updated-

lymphatic/lymph7.html

L h N dL h N d


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Lymph flowing in along

these branches isdirected to the outside

of the node, and must

flow through channels

called lymphatic

sinuses within the

node to get to the

outgoing vessel in theregion called the hilus

of the node.

http://www.jdaross.mcmail.com/lymphnode.htm

L h N dL h N d


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These channels are

lined with

lymphocytes and

macrophages.

As it passes through

the lymph node, the

lymph is filtered pastthese cells.

http://www.jdaross.mcmail.com/lymphnode.htm

L h N dL h N d


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The lymph may contain debris including micro-organisms of

varying types that have penetrated the body's defence

barriers, phagocytic cells that may have been attracted to

such a breach (some of which may either be alive or dead,and some of which may contain ingested microbes or other

materials), damaged or worn-out tissue cells, cells from

malignant tumours, orinhaled particles in nodes downstream

from respiratory passages or the lungs.



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As these materials are exposed to the lymphocytes and

macrophages, their organic components are eitherphagocytosed by the macrophages or destroyed by antibodies

made by the B-lymphocytes.



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There are usually several lymph nodes between a region of

tissue and the venous system. This means that material that

was not filtered off and successfully dealt with in one lymph

node passes on to the next and so on.

By the time the lymph reaches the blood it has usually been

cleaned of all impurities such as cell debris and foreign

bodies.



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In some instances where phagocytation is incomplete thenode may swell.

You may well have experienced swollen cervical lymph nodes.

These often accompany a sore throat due to streptococcalinfection.

Infections in almost any part of the body may result in swelling

and tenderness of the lymph nodes associated with that partof the body.



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Activated T and B lymphocytes multiply in the lymph nodes,and T and B lymphocytes are added to the lymph as it flows

through the sinuses.

The lymph leaving the node therefore carries lymphocytes thatwill eventually pass into the blood.

Antibodies produced by the B lymphocytes enter the lymph

and the blood draining the node.



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Lymph nodes are therefore important to us clinically.

If we know the route by which a body part is drained, andwhich groups of lymph nodes lie along the route taken by the

vessels that drain it, then we can assess those nodes for

swelling and hardness (induration) and tenderness to

palpation.

Regional Lymph NodesRegional Lymph Nodes


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We learn about the regional lymph nodes in the head and

neck so that we can assess them to determine the spread ofinfection, and in some cases, so we can ensure that we

remove all those nodes that may be affected by a spreading

cancer.



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We can divide the nodes of the head and neck into superficial

groups and deep groups.

The superficial groups tend to be more important to us

clinically, because we can palpate them directly.



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Superficial Groups:

Deep Groups:

Pericervical r ing

Nodes accompanying superficial neck veins

Perivisceral ring

Deep cervical chain

Pericervical RingPericervical Ring


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This group is clinically important and comprises:

Submental Group

Submandibular Group

Parotid or Pre-auricular Group

Mastoid Group

Occipital Group



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e ce ca ge ce ca g

These groups of

nodes drain the

surface tissues

of the head and

the face.

From Grays Anatomy, Longman,

London, 35th Ed 1973p. 729



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gg

The drainage

pattern is

shown on this

diagram.



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gg

The scalp drains

into all nodes, while

the eyelids andcheeks drain into

the parotid and

submandibular

groups.



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gg

The external nose and

the upper lip drain into

the submandibulargroup, while the lower

lip drains into the

submental and

submandibulargroups.



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The floor of the mouthat the sides drains into

the submandibular

group and also to thedeep cervical chain.

The lateral parts of the

lips drain into the

submandibular group.



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The tip of the tongue, the

central parts of the floor of

the mouth and the lower lipdrain bilaterally into the

submental group.

Anterior teeth as far back asthe canines drain into the

submandibular and

submental groups, and

premolar and molar teethdrain into the parotid group

and the deep cervical chain.

Superficial NeckSuperficial Neck


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The nodes accompanying

superficial neck veins are

also clinically important,

since they are easily

palpable in the clinic, and

tell us about superficial

infections and systemicinfections.

These lie in two chains

which follow the anterior

jugular vein and the

external jugular vein

respectively.

Superficial NeckSuperficial Neck


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The nodes in the group

following the external

jugular vein are particularlyeasily palpated in the living

individual because they lie

superficially to the

sternocleidomastoidmuscle.

You should take care to be

sure you can recognizethese as distinct from the

nodes of the deep cervical

chain.

Perivisceral RingPerivisceral Ring


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The most anterior group of these nodes changes its name as itascends in the neck, according to the structures alongside

which it lies at any particular level:

pre-tracheal nodes

pre-laryngeal nodes

infrahyoid nodes

These lie anteriorly in the neck, in front of the larynx and

trachea.



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The posterior group also changes its name in the same way.

Thus, we have:

retro-oesophageal nodes

retro-pharyngeal nodes



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The paratracheal group lies laterally alongside the trachea.

The entire group surrounds the larynx, trachea and

oesophagus, giving rise to its name, the perivisceral ring,

since it surrounds the neck viscera.

Deep Cervical ChainDeep Cervical Chain


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The deep cervical chain is difficult to

palpate for most of its course since itlies deep to the sternocleidomastoid

muscle, but at its upper and lower

ends, it has two major nodes named

for muscles close to which they lie.

These are thejugulodigastric node

(upper) and thejugulo-omohyoid

node (lower).

The other nodes in this chain are not

named.



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All of the lymph from the head and

neck eventually drains into the deepcervical chain on both sides.

Premolar and molar teeth drain into

its upper nodes, as do the sides ofthe tongue and the floor of the mouth

at the sides.

The palate drains into the upper

nodes, and the pericervical groups

also drain into this chain.



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The deep cervical chain drains intothe right lymphatic duct on the right

side, and into the thoracic duct on the

left.



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On completion of this topic you should be able to describe

the general plan of the lymphatic drainage of the head

and neck.

You should be able to describe the positions of all the

major groups of lymph nodes.



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You should be able to describe and demonstrate the

ability to assess clinically the spread of infection in the

head and neck using the major lymph node groups.

You should demonstrate an understanding of the role

played by the lymphatic system in controlling and

directing the spread of infection and certain neoplasiain the head and neck.


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