Venous Drainage Condensed Grayscale Slides

7/27/2019 Venous Drainage Condensed Grayscale Slides

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Venous DrainageVenous 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 session, you should be able to

describe the general plan of both the blood supply to and

venous drainage of the head and neck.

You should be able to describe the venous sinuses of the

cranial cavity and specifically discuss the connections of the

cavernous sinus.


You should also be able to describe the superficial venousdrainage of the head and neck in general terms, with an

explicit statement that the veins in the head and neck have

no valves to control the direction of blood flow.


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VariationVariation

The veins in the body are among the most variable of all

anatomical structures. Because of this, there is little point

in learning great detail for superficial veins, and we will

instead concentrate only on the general plan.

We will, however, examine the cranial drainage in somedetail, since many constant features appear in the

structures concerned.

Venous Sinuses

Venous SinusesVenous Sinuses

In the cranium,

there are both

veins and venoussinuses.

Venous sinuses

are formed by

folds in the dura

mater.

From Grays Anatomy, 35th Ed, Longman, London 1973, p. 497


Wherever the dura

folds, it leaves a

small space

between the folded

layers where theyabut bone or where

they fold back on

each other, and

these spaces carry

blood into the

venous system.From Grays Anatomy, 35th Ed, Longman, London 1973, p. 497


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They are lined by endothelium, and serve the same function

as veins elsewhere in the body.


Major sinuses you should recognize include:

Superior Sagittal Sinus

Transverse Sinus

Sigmoid Sinus

Superior Petrosal Sinus

Inferior Petrosal Sinus

Cavernous Sinus

Intercavernous Sinus

Sphenoparietal Sinus

Straight Sinus


It is important that you realise that none of these sinusespossess valves, and this means that blood flow can run in any

direction depending on external factors such as gravity and

position.

This is a most important factor in terms of the spread of

infection.


A 3-D cast ofthe sinuses

might look

something like

this



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While most of the cranial

venous blood is drained

ultimately through the

sigmoid sinus which runs

through the jugular canal

to become the internal

jugular vein, sinuses alsoconnect throughout the

head and neck to the

facial circulation and that

of the scalp.



Once again, just as

with arteries, it is

important to realise

that the entire system

is interconnected, and

that this has importantclinical implications.





Some of these connections

are of great clinicalimportance, and in

particular you should

recognize the major

connections of the

cavernous sinus, which lies

centrally in the calvaria.



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The middle and

inferior cerebral

veins drain into the

cavernous sinus, as

does thesphenoparietal

sinus.



It connects with the orbital circulation via the superior

ophthalmic vein, and through the superior ophthalmic vein to

the facial or angular vein.



The cavernous sinus

is typically described

as draining into the

superior petrosalsinus and thus into the

sigmoid sinus, and

more directly into the

internal jugular vein

via the inferior

petrosal sinus



but it should always be remembered that this isdependent on the orientation of the head and the forces

acting on it, since none of these structures has any valves

to control the flow of blood.


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The cavernous sinuses

communicate across the

midline via the anterior

and posterior

intercavernous sinuses

around thehypophysis



and they communicate with the pterygoid plexus via the

sphenoidal emissary vein which runs through the

sphenoidal emissary foramen (40% of skulls), and by

small veins running through foramen ovale and passing

through the cartilage plug of foramen lacerum.

From

Grays

Anatomy,

35th Ed,

Longman,

London

1973, p.

288


The biggest driving force on blood in the cavernous sinus is

the pulsing of the internal carotid artery which sits inside the

sinus, although is separated from it by a single layer of

endothelium.


Veins


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VeinsVeins

The internal jugular vein

arises from the sigmoid

sinus at the inferior end

of the jugular canal. It

runs in the carotid

sheath with the internal

and common carotid

arteries and the vagus

nerve.

Jamieson, EB. Illustrations of Regional Anatomy, Section II.

Edinburgh, E & S Livingstone, 8th Ed. p.26, Diagram 77.

VeinsVeins

It joins the subclavian

vein to form the

brachiocephalic or

innominate vein.

The internal jugular

vein also drains thefacial vein.

Van De Graff, K. Human Anatomy, Iowa,

Wm. C. Brown, 2nd Ed., 1988. p. 526

VeinsVeins

The anterior jugular

vein drains into the

external jugular vein.

This vein drains moreanterior and central

structures in the neck,

and has a large

communication with its

partner on the other

side of the neck.


VeinsVeins

The external jugular

vein is formed at the

junction of the

posterior auricular veinand the posterior

retromandibular vein.

It runs down through

the neck to drain into

the subclavian vein.



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VeinsVeins

The posterior

retromandibular vein is

joined to the facial vein

by the anterior

retromandibular, which

establishes theconnection between

the external and

internal jugular veins.


VeinsVeins

The veins of the head

have no valves, and

this means that

venous drainage can

be bidirectional, which

once again hasimplications for the

spread of infection.


VeinsVeins

Once again, the veinsform a great plexus in

the face, scalp and

cranial cavity, and

drainage can occur by

any available route.


VeinsVeins

Note the so-called

dangerous triangle.

Veins draining this areacan drain directly back

into the superior

ophthalmic vein,

leading to the

cavernous sinuses.

Moore, KL, Clinically Oriented Anatomy, Williams & Wilkins,

Baltimore 1980, p. 1061.


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Pterygoid PlexusPterygoid Plexus

The pterygoid

plexus is a

large network

of veins lying

between the

lateral and

medial

pterygoids,

and betweenlateral

pterygoid and

temporalis.

Netter, F. 1989, Atlas of Human Anatomy, Summit, New Jersey, Ciba-Geigy Medical, Plate 64.


It is widely

connected. It

communicates

with the facial

circulation via

the deep facial

vein, and thus

to the orbital

venous

circulation.



It connects

with the

cavernous

sinus via

foramen ovale,sphenoidal

emissary

foramen and

foramen

lacerum.



It also receives

branches from

the dental

veins,

sphenopalatine

and greater

palatine veins.



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VeinsVeins

All blood from the subclavian veins drains back into the

superior vena cava, which opens into the right atrium of the

heart.

Lymph is collected into the left subclavian vein through the

thoracic duct, and into the right subclavian vein through the

right lymphatic duct.

Surgical PlasticitySurgical Plasticity

When a part is removed, replaced or repaired, the blood

supply of the region may be altered.

In addition, new vessels, both arterial and venous, may growto supply neoplasia in some instances.


The important point to realise is that the blood system as

described in this series of lectures is that of a normal,previously uninjured person.

If surgical intervention or injury or other modification occurs,

then the blood vascular system will modify itself as required

to cope. Entirely new vessels may form, or existing vessels

may widen or narrow.


Surgeons can take advantage of this adaptability whenplanning operations, provided they ensure that an

adequate blood supply is available to tissues upon which

they operate in the first instance.


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How might this apply to us in Dentistry?

What is the blood supply to the periodontium and why is it

important to us?

Blood Supply o f the Periodontal LigamentBlood Supply o f the Periodontal Ligament

The blood supply arises from the inferior dental branch, and

from the posterior, middle and superior dental branches of

the maxillary artery.

The blood reaches the periodontal ligament via three routes:apical vessels, alveolar bone vessels, and anastomosing

vessels from the gingiva.

The blood reaches the

periodontal ligament by three

routes:

apical vessels

alveolar bone vessels

anastomosing vessels from the gingiva.

Blood Supply o f the Periodontal LigamentBlood Supply o f the Periodontal Ligament

Modified from: Manson, JD, Periodontics, 3 rd

Edition, Henry Kimpton, London 1975, p.10

Note the perforations in the socket

wall to allow the vessels from the

alveolar bone to enter.

The socket wall is known as thecribriform plate for this reason.

It is NOT called the lamina dura,

which is the radiographic feature

resulting from the thickness of the

bone of the socket wall absorbing

x-rays

Blood Supply of the Periodontal LigamentBlood Supply of the Periodontal Ligament

From Ten Cate, AR, Oral

Histology, CV Mosby Co, St.

Louis, 1980, p. 253


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Blood Supply of the Periodontal LigamentBlood Supply of the Periodontal Ligament

This has important implications for us in periodontal surgery.

If we wish to raise a periodontal flap to expose alveolar

bone, we need to ensure that the raised tissue flap maintains

an adequate blood supply to allow it to live and to permit

healing.

How might we do this?


On completion of this session, you should be able to

describe the general plan of both the blood supply to and

venous drainage of the head and neck.

You should be able to describe the venous sinuses of thecranial cavity and specifically discuss the connections of the

cavernous sinus.


You should also be able to describe the superficial venousdrainage of the head and neck in general terms, with an

explicit statement that the veins in the head and neck have

no valves to control the direction of blood flow.

The End

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