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Lymphatic DrainageLymphatic Drainage

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

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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 headand neck.

You should be able to describe the positions of all the

major groups of lymph nodes.

Learning GoalsLearning Goals

You should be able to describe and demonstrate the

ability to assess clinically the spread of infection in thehead 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 reabsorbed

into the blood capillaries during circulation, with the

absorption of fat from the small intestine, and mostimportantly, with immunity.

LymphaticsLymphatics

It consists of lymphatic capillaries and vessels, lymph

nodes, organs such as the thymus, spleen and bone

marrow, and with masses of lymphatic tissue in the

walls of the alimentary tract, together with circulatingcells.

LymphaticsLymphatics

In our discussion of the lymphatics in this session, we

will restrict ourselves to a discussion of the structuralcomponents of the lymphatic system and the various

groups 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.

Vascular SystemVascular System

Recall that the blood vascular system is a body system

that deals with two of the body's most importantfunctions: 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.

Fluid MovementFluid Movement

The heart acts as

the fluid pump

within the body.

It pumps blood into

arteries, andreceives blood from

veins.

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

Fluid MovementFluid Movement

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

Fluid MovementFluid Movement

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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Fluid MovementFluid Movement

Blood leaving the heart initially

flows through large arteries. As

these arteries become more distant

from the heart, they subdivide,

becoming smaller vessels known

as arterioles.

Arteries and arterioles have

significant amounts of smoothmuscle in their walls, and this helps

maintain 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

Fluid MovementFluid Movement

Finally blood flows into smaller

vessels still, known as

capillaries.

Capillaries are incredibly

numerous, but are small in

cross-section, and are quitepermeable to a number of

substances including fluid from

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

s/Vascular/Vascular.htm

Fluid MovementFluid Movement

Due to the blood pressure in the

initial part of the capillary, some

of the plasma is filtered throughthe vessel wall and emerges

from the capillary.

This is the source of the

interstitial fluid, the fluid that lies

between the cells of the body.

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

ages/bloodvessels_4.gif

Fluid MovementFluid Movement

You may think of interstitial fluid as resulting in somerespects 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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Fluid MovementFluid Movement

As the blood pressure falls

along the length of the

capillary, it becomes

comparable with the

osmotic force exerted by the

concentration of large

molecules remaining in thecapillary lumen that did not

escape into the surrounding

tissues. http://www.chelationtherapyonline.com/articles/images/bloodvessels_4.gif

Fluid MovementFluid Movement

As we move further

along the capillary, and

the blood pressure

drops still further, the

osmotic force begins to

dominate, setting up an

osmotic gradient thatfavours the return of the

interstitial fluid back into

the capillary.

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

532

Fluid MovementFluid Movement

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

Fluid MovementFluid Movement

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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Fluid MovementFluid Movement

Here, it passes into

lymphatic vessels, during

its passage along which it

will pass through lymph

nodes.

The lymph nodes play arole in controlling the

spread of infection and in

fighting it.

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

Ed. P 532

Fluid MovementFluid Movement

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, 35 th Ed 1973p.

727.

Fluid MovementFluid Movement

The remainder of the blood

returns to the heart through

larger vessels, venules,

which lead to veins, and

these, in turn, return to the

heart.

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

Ed. P 532

Fluid MovementFluid Movement

Now that we can see the broad relationship between the

three types of fluid, blood, lymph and interstitial fluid, and

how 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.

Lymphatic CapillariesLymphatic Capillaries

Lymphatic capillaries are

tiny thin-walled vessels

that begin as blind tubes

in the spaces between

cells in most tissues of

the body except in

cartilage and the central

nervous system, the

epidermis including the

hair and nails, cornea of

the eye, and also bone

marrow.www.an