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CONTENTS

1. BLOOD SUPPLY

I. INTRODUCTION

II. DEVELOPMENT

III. ARTERIAL SUPPLY

IV. VENOUS DRAINAGE

V. CLINICAL CONSIDERATIONS

2. LYMPHATIC DRAINAGE

I. INTRODUCTION

II. DEVELOPMENT

III. LYMPHATIC DRAINAGE

IV. CLINICAL EXAMINATION OF LYMPH NODES

V. CLINICAL CONSIDERATIONS

3. SUMMARY

4. REFERENCES

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INTRODUCTION

The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and the tissues; and the veins, which carry blood from the capillaries back toward the heart.

Types

Arteries o Aorta (the largest artery, carries blood out

of the heart) o Branches of the aorta, such as the carotid

artery, the subclavian artery, the celiac trunk, the mesenteric arteries, the renal artery and the iliac artery.

Arterioles

Capillaries (the smallest blood vessels)

Venules

Veins o Large collecting vessels, such as the

subclavian vein, the jugular vein, the renal vein and the iliac vein. o Venae cavae (the 2 largest veins, carry blood into the heart)

DEVELOPMENT

The first blood vessels, consisting only of endothelial cells, form from mesenchymal precursors (angioblasts), the process known as vasculogenesis. The formation begins in 3rd week of intra uterine life. New blood vessels form by extension of existing blood vessels, the process called angiogenesis.

ARTERIAL SUPPLY

Common carotid artery

The common carotid artery is an artery that supplies the head and

neck with oxygenated blood; it divides in the neck to form the external and

internal carotid arteries.

Structure

The common carotid artery is a paired structure, meaning that

there are two in the body, one for each half. The left and right common

carotid arteries follow the same course with the exception of their origin.

The right common carotid originates in the neck from the brachiocephalic

trunk. The left arises from the aortic arch in the thoracic region.

The left common carotid artery can be thought of as having two

parts: a thoracic (chest) part and a cervical (neck) part. The right common

carotid originates in or close to the neck, so it lacks a thoracic portion.

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Thoracic part

Only the left common carotid artery has a substantial presence in the thoracic region. It

originates along the aortic arch, and travels upward through the superior mediastinum to the

level of the left sternoclavicular joint, where it is continuous with the cervical portion.

Relations

During the thoracic part of its course, the left common carotid artery is related to the

following structures: In front, it is separated from the manubrium of the sternum by the

sternohyoid and sternothyroid muscles, the anterior portions of the left pleura and lung, the left

brachiocephalic vein, and the remains of the thymus; behind, it lies on the trachea, esophagus,

left recurrent laryngeal nerve, and thoracic duct.

To its right side below is the brachiocephalic trunk, and above, the trachea, the inferior

thyroid veins, and the remains of the thymus; to its left side are the left vagus and phrenic

nerves, left pleura, and lung. The left subclavian artery is posterior and slightly lateral to it.

Cervical part

The cervical portions of the common carotids resemble each other so closely that one

description will apply to both. Each vessel passes obliquely upward, from behind the

sternoclavicular joint to the level of the upper border of the thyroid cartilage, where it divides.

At approximately the level of the fourth cervical vertebra, the common carotid artery

bifurcates into an internal carotid artery (ICA) and an external carotid artery (ECA). While both

branches travel upward, the internal carotid takes a deeper (more internal) path, eventually

travelling up into the skull to supply the brain via the carotid canal. The external carotid artery

travels more closely to the surface, and sends off numerous branches that supply the neck and

face.

Both branches travel upward, the internal carotid takes a deeper (more internal) path, travelling

up into the skull to supply the brain via the carotid canal.

External Carotid Artery

The external carotid artery is a major artery of the head and neck. It arises from the

common carotid artery when it bifurcates into the external and internal carotid artery.

Course

The external carotid artery begins at the level of the upper border of thyroid cartilage,

and, taking a slightly curved course, passes upward and forward, and then inclines backward to

the space behind the neck of the mandible, where it divides into the superficial temporal and

maxillary artery within the parotid gland.

It rapidly diminishes in size in its course up the neck, owing to the number and large size

of the branches given off from it.

In the child, it is somewhat smaller than the internal carotid; but in the adult, the two

vessels are of nearly equal size. At its origin, this artery is more superficial, and placed nearer

the middle line than the internal carotid, and is contained within the carotid triangle.

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Relations

The external carotid artery is covered by the skin, superficial fascia, Platysma, deep

fascia, and anterior margin of the Sternocleidomastoideus; it is crossed by the hypoglossal

nerve, by the lingual, ranine, common facial, and superior thyroid veins; and by the Digastricus

and Stylohyoideus; higher up it passes deeply into the substance of the parotid gland, where it

lies deep to the facial nerve and the junction of the temporal and internal maxillary veins.

Medial to it are the hyoid bone, the wall of the pharynx, the superior laryngeal nerve, and

a portion of the parotid gland.

Lateral to it, in the lower part of its course, is the internal carotid artery.

Posterior to it, near its origin, is the superior laryngeal nerve; and higher up, it is

separated from the internal carotid by the Styloglossus and Stylopharyngeus, the

glossopharyngeal nerve, the pharyngeal branch of the vagus, and part of the parotid gland.

Branches

Arising in carotid triangle o Superior thyroid artery o Ascending pharyngeal artery o Lingual artery o Facial artery o Occipital artery

Posterior auricular artery

Terminal branches o Maxillary artery o Superficial temporal artery

Superior Thyroid Artery

The superior thyroid artery arises from the external carotid artery just below the level of

the greater cornu of the hyoid bone and ends in the thyroid gland.

Relations

From its origin under the anterior border of the Sternocleidomastoideus it runs upward

and forward for a short distance in the carotid triangle, where it is covered by the skin,

Platysma, and fascia; it then arches downward beneath the Omohyoideus, Sternohyoideus, and

Sternothyreoideus.To its medial side are the Constrictor pharyngis inferior and the external

branch of the superior laryngeal nerve.

Branches

It distributes twigs to the adjacent muscles, and numerous branches to the thyroid gland,

anastomosing with its fellow of the opposite side, and with the inferior thyroid arteries.

The branches to the gland are generally two in number;

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Besides the arteries distributed to the muscles and to the thyroid gland, the branches of the

superior thyroid are:

Hyoid (infrahyoid) artery

Sternocleidomastoid artery

Superior laryngeal artery

Cricothyroid artery

Ascending Pharyngeal Artery

The ascending pharyngeal artery, the smallest branch of the external carotid, is a long,

slender vessel, deeply seated in the neck, beneath the other branches of the external carotid

and under the Stylopharyngeus.

Its branches are listed here: Pharyngeal branches of ascending pharyngeal artery.

It arises from the back part of the external carotid, near the commencement of that

vessel, and ascends vertically between the internal carotid and the side of the pharynx, to the

under surface of the base of the skull, lying on the Longus capitis.

Lingual Artery

The Lingual Artery arises from the external carotid between the superior thyroid and

facial artery. It can be located easily in the tongue.

It first runs obliquely upward and medialward to the greater cornu of the hyoid bone.

It then curves downward and forward, forming a loop which is crossed by the

hypoglossal nerve, and passing beneath the Digastricus and Stylohyoideus it runs horizontally

forward, beneath the Hyoglossus, and finally, ascending almost perpendicularly to the tongue,

turns forward on its lower surface as far as the tip, under the name of the deep lingual artery

(profunda linguae ).

Branches

1. suprahyoid branch of lingual artery 2. dorsal lingual branches of lingual artery 3. deep lingual artery 4. sublingual artery

Facial Artery

The facial artery (external maxillary artery in older texts) is a branch of the external

carotid artery that supplies structures of the face.

The facial artery arises in the carotid triangle from the external carotid artery a little

above the lingual artery and, sheltered by the ramus of the mandible, passes obliquely up

beneath the digastric and stylohyoid muscles, over which it arches to enter a groove on the

posterior surface of the submandibular gland.

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It then curves upward over the body of the mandible at the antero-inferior angle of the

masseter; passes forward and upward across the cheek to the angle of the mouth, then ascends

along the side of the nose, and ends at the medial commissure of the eye, under the name of the

angular artery.

This vessel, both in the neck and on the face, is remarkably tortuous: in the former

situation, to accommodate itself to the movements of the pharynx in deglutition; and in the latter,

to the movements of the mandible, lips, and cheeks.

Relations

In the neck, its origin is superficial, being covered by the integument, platysma, and

fascia; it then passes beneath the digastric and stylohyoid muscles and part of the

submandibular gland, but superficial to the hypoglossal nerve.

It lies upon the middle pharyngeal constrictor and the superior pharyngeal constrictor,

the latter of which separates it, at the summit of its arch, from the lower and back part of the

tonsil.

On the face, where it passes over the body of the mandible, it is comparatively

superficial, lying immediately beneath the dilators of the mouth. In its course over the face, it is

covered by the integument, the fat of the cheek, and, near the angle of the mouth, by the

platysma, risorius, and zygomaticus major. It rests on the buccinator and levator anguli oris, and

passes either over or under the infraorbital head of the levator labii superioris.

The anterior facial vein lies lateral/posterior to the artery, and takes a more direct course

across the face, where it is separated from the artery by a considerable interval. In the neck it

lies superficial to the artery.

The branches of the facial nerve cross the artery from behind forward.

The facial artery anastomoses with (among others) the dorsal nasal artery of the internal

carotid artery.

Branches

The branches of the facial artery are:

cervical o Ascending palatine artery o Tonsillar branch o Submental artery o Glandular branches

facial o Inferior labial artery o Superior labial artery o Lateral nasal branch to nasalis muscle o Angular artery - the terminal branch

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Muscles supplied by the facial artery include:

buccinator

levator anguli oris

levator labii superioris

levator labii superioris alaeque nasi

levator veli palatini

masseter

mentalis

mylohyoid

nasalis

palatoglossus

palatopharyngeus

platysma

procerus

risorius

styloglossus

transverse portion of the nasalis

Occipital Artery

The occipital artery arises from the external carotid artery opposite the facial artery, its

path is below the posterior belly of digastric to the occipital region. This artery supplies blood to

the back of the scalp and sterno-mastoid muscles. Other muscles it supplies are deep muscles

in the back and neck.

At its origin, it is covered by the posterior belly of the Digastricus and the Stylohyoideus,

and the hypoglossal nerve winds around it from behind forward; higher up, it crosses the

internal carotid artery, the internal jugular vein, and the vagus and accessory nerves.

It next ascends to the interval between the transverse process of the atlas and the

mastoid process of the temporal bone, and passes horizontally backward, grooving the surface

of the latter bone, being covered by the Sternocleidomastoideus, Splenius capitis, Longissimus

capitis, and Digastricus, and resting upon the Rectus capitis lateralis, the Obliquus superior,

and Semispinalis capitis. It then changes its course and runs vertically upward, pierces the

fascia connecting the cranial attachment of the Trapezius with the Sternocleidomastoideus, and

ascends in a tortuous course in the superficial fascia of the scalp, where it divides into

numerous branches, which reach as high as the vertex of the skull and anastomose with the

posterior auricular and superficial temporal arteries.

Branches

1. Sternocleidomastoid branches: They are 2 in number and are given off in the Carotid triangle. The upper branch accompanies the accessory nerve, and the lower branch arises near the origin of the occipital artery.

2. Auricular branch 3. Mastoid branch 4. Descending branches 5. Occipital branches

Its terminal portion is accompanied by the greater occipital nerve.

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Posterior Auricular Artery

The posterior auricular artery is a small artery and arises from the external carotid artery, above the Digastric muscle and Stylohyoid muscle, opposite the apex of the styloid process.

It ascends posteriorly beneath the parotid gland, along the styloid process of the temporal bone, between the cartilage of the ear and the mastoid process of the temporal bone along the lateral side of the head. The posterior auricular artery supplies blood to the scalp posterior to the auricle and to the auricle itself.

Maxillary Artery

The maxillary artery is an artery that supplies deep structures of the face. It comes just out

behind the neck of the mandible.

The maxillary artery, the larger of the two terminal branches of the external carotid artery,

arises behind the neck of the mandible, and is at first imbedded in the substance of the parotid

gland; it passes forward between the ramus of the mandible and the sphenomandibular

ligament, and then runs, either superficial or

deep to the lateral pterygoid muscle, to the

pterygopalatine fossa.

It supplies the deep structures of the face, and

may be divided into mandibular, pterygoid, and

pterygopalatine portions.

First portion

The first or mandibular portion passes

horizontally forward, between the neck of the

mandible and the sphenomandibular ligament,

where it lies parallel to and a little below the auriculotemporal nerve; it crosses the inferior

alveolar nerve, and runs along the lower border of the lateral pterygoid muscle.

Branches include:

Deep auricular artery

Anterior tympanic artery

Middle meningeal artery

Inferior alveolar artery which gives off its mylohyoid branch just prior to entering the mandibular foramen

Accessory meningeal artery

Second portion

The second or pterygoid portion runs obliquely forward and upward under cover of the ramus of

the mandible and insertion of the temporalis, on the superficial (very frequently on the deep)

surface of the lateral pterygoid muscle; it then passes between the two heads of origin of this

muscle and enters the fossa.

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Branches include:

Masseteric artery

Pterygoid branches

Deep temporal arteries (anterior and posterior)

Buccal artery

Third portion

The third or pterygopalatine portion lies in the pterygopalatine fossa in relation with the

pterygopalatine ganglion. This is considered the terminal branch of the maxillary artery.

Branches include:

Sphenopalatine artery (Nasopalatine artery is the terminal branch of the Maxillary artery)

Descending palatine artery

Infraorbital artery

Posterior superior alveolar artery

Artery of pterygoid canal

Pharyngeal artery

Superficial Temporal Artery

The superficial temporal artery is a major artery of the head. It arises from the external

carotid artery when it bifurcates into the superficial temporal artery and maxillary artery.

It begins in the substance of the parotid gland, behind the neck of the mandible, and passes

superficially over the posterior root of the zygomatic process of the temporal bone; about 5 cm.

above this process it divides into two branches, a frontal and a parietal.

As it crosses the zygomatic process, it is covered by the Auricularis anterior muscle, and by

a dense fascia; it is crossed by the temporal and zygomatic branches of the facial nerve and one

or two veins, and is accompanied by the auriculotemporal nerve, which lies immediately behind

it.

The superficial temporal artery anastomoses with (among others) the supraorbital artery of

the internal carotid artery.

Internal Carotid Artery

It has a dilation at its root called the carotid sinus. The artery enters the skull through the carotid canal. It does not give off any branch in the neck and face but gives off the ophthalmic artery which supplies the optic nerve, eye, orbit and scalp. It enters through optic canal inferolateral to the optic nerve, crosses the nerve superiorly from lateral to medial side along with the nasociliary nerve, then run forwards along the medial wall of the orbit and terminates near the medial angle of the eye

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Branches

Central artery of retina Lacrimal Artery Posterior ciliary arteries Supra-orbital artery Anterior Ethmoidal artery Posterior Ethmoidal Artery Dorsal nasal Artery Supratrochlear Artery Medial Palpebral Branches

The central artery of retina is an end artery and destruction of this artery by an embolism or pressure results in sudden total blindness

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Facial Vein

The anterior facial vein (facial vein) commences at the side of the root of the nose, and is a direct continuation of the angular vein where it also receives a small nasal branch. It lies behind the facial artery and follows a less tortuous course. It receives blood from the external palatine vein before it either joins the anterior branch of the retromandibular vein to form the common facial vein, or drains directly into the internal jugular vein.

From its origin it runs obliquely downward and backward, beneath the Zygomaticus and zygomatic head of the Quadratus labii superioris, descends along the anterior border and then on the superficial surface of the Masseter, crosses over the body of the mandible, and passes obliquely backward, beneath the Platysma and cervical fascia, superficial to the submandibular gland, the Digastric and Stylohyoid.

The facial vein has no valves, and its walls are not so flaccid as most superficial veins.

Jugular vein

The jugular veins are veins that bring deoxygenated blood from the

head back to the heart via the superior vena cava.

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Internal Jugular Veins

The two internal jugular veins collect the blood from the brain, the superficial parts of the

face, and the neck.

The inferior petrosal sinus and the sigmoid sinus join to form each internal jugular vein, and

begins in the posterior compartment of the jugular foramen, at the base of the skull.

At its origin, it is somewhat dilated, and this dilatation is called the superior bulb.

It also has a common trunk into which drains the anterior branch of the retromandibular vein, the

facial vein, and the lingual vein.

It runs down the side of the neck in a vertical direction, being at one end lateral to the internal

carotid artery, and then lateral to the common carotid, and at the root of the neck, it unites with

the subclavian vein to form the brachiocephalic vein (innominate vein); a little above its

termination is a second dilatation, the inferior bulb.

Above, it lies upon the rectus capitis lateralis, behind the internal carotid artery and the nerves

passing through the jugular foramen; lower down, the vein and artery lie upon the same plane,

the glossopharyngeal and hypoglossal nerves passing forward between them; the vagus

descends between and behind the vein and the artery in the same sheath (the carotid sheath),

and the accessory runs obliquely backward, superficial or deep to the vein.

At the root of the neck, the right internal jugular vein is a little distance from the common carotid

artery, and crosses the first part of the subclavian artery, while the left internal jugular vein

usually overlaps the common carotid artery.

The left vein is generally smaller than the right, and each contains a pair of valves, which are

placed about 2.5 cm above the termination of the vessel.

External Jugular Vein

The external jugular vein receives the greater part of the blood from the exterior of the cranium

and the deep parts of the face, being formed by the junction of the posterior division of the

retromandibular vein with the posterior auricular vein.

It commences in the substance of the parotid gland, on a level with the angle of the mandible,

and runs perpendicularly down the neck, in the direction of a line drawn from the angle of the

mandible to the middle of the clavicle at the posterior border of the sternocleidomastoideus.

In its course it crosses the sternocleidomastoideus obliquely, and in the subclavian triangle

perforates the deep fascia, and ends in the subclavian vein lateral to or in front of the scalenus

anterior, piercing the roof of the posterior triangle.

It is separated from the sternocleidomastoideus by the investing layer of the deep cervical

fascia, and is covered by the platysma, the superficial fascia, and the integument; it crosses the

cutaneous cervical nerve, and its upper half runs parallel with the great auricular nerve.

The external jugular vein varies in size, bearing an inverse proportion to the other veins of the

neck, it is occasionally double.

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The external jugular vein has 8 branches with 5 being in the neck. The 5 branches are the

ascending pharyngeal, superior thyroid, lingual, facial, and occipital veins.

Pterygoid Plexus

It is a venous plexus situated between the temporalis muscle and lateral pterygoid muscle. It is formed by Sphenopalatine vein, deep temporal vein, pterygoid vein, masseteric vein, buccal vein, alveolar veins, greater palatine veins, middle meningeal veins, branches from ophthalmic vein. It drains into facial vein via deep facial vein.

CLINICAL CONSIDERATIONS

The jugular veins are relatively superficial and unprotected. Due to the large volumes of blood that flow though the jugular veins, damage to the jugulars can quickly cause significant blood loss which can lead to hypovolemic shock and then death if not treated

Littles Area

It is a region in the anteroinferior part of the nasal

septum. The four arteries anastomose to form a vascular

plexus called Kiesselbach's plexus. They are anterior ethmoid

artery, greater palatine artery, sphenopalatine artery, superior

labial artery. Bleeding of nose (epistaxis) occurs in Little's area

Danger Triangle of the Face

The danger triangle of the face consists of the area from the corners of the mouth to the bridge of the nose, including the nose and maxilla. Due to the special nature of the blood supply to the human nose and surrounding area, it

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is possible (although very rare) for retrograde infections from the nasal area to spread to the brain.

This is possible because of venous communication (via the ophthalmic veins) between the facial vein and the cavernous sinus. The cavernous sinus lies within the cranial cavity, between layers of the meninges and is a major conduit of venous drainage from the brain.

It is a common misconception that the veins of the head do not contain one way valves like other veins of the circulatory system. In fact, it is not the absence of venous valves but the existence of communications between the facial vein and cavernous sinus and the direction of blood flow that is important in the spread of infection from the face.

An example of disease that may be caused by this process is meningitis, an inflammation of the meninges, the coverings of the brain. Such bacterial infections can be caused by pus entering the brain's blood supply if pimples in the danger triangle are pricked

Atherosclerosis

Atherosclerosis (also known as arteriosclerotic vascular disease or ASVD) is a condition in which an artery wall thickens as the result of a build-up of fatty materials such as cholesterol. It is a syndrome affecting arterial blood vessels, a chronic inflammatory response in the walls of arteries.

Hematoma

Hematoma is caused by the limitation of the blood to a subcutaneous or intramuscular tissue space isolated by fascial planes

Petechiae is a small pinpoint hematomas less than 3 mm in diameter

Purpura (purple) is a bruise about 1 cm in diameter, generally round in shape

Ecchymosis is subcutaneous extravasation of blood in a thin layer under the skin, i.e. bruising or "black and blue".

Hematoma is commonly produced during posterior superior alveolar nerve block by inserting the needle too far posteriorly into the pterygoid plexus of veins and also the maxillary artery may be punctured. A visible intraoral hematoma develops within few miuntes, usually noted in the buccal tissues of the mandibular region

Cavernous Sinus thrombosis

Formation of thrombus in the cavernous sinus or its communicating branches. Head, face and intraoral structures above the maxilla are the most prone areas. Face and lips communicate by facial and angular veins. Dental infection is carried by pterygoid plexus. Infection spreading through pterygoid or internal route has a much slower course than external route. Infection spreading by the facial or external route is very rapid with a short fulminating course because of the large, open system of veins leading directly to the cavernous sinus. The use of antibiotics has decreased mortality but the condition is still serious

Hemangioma

Hemangioma is a benign swelling or growth of endothelial cells, the cells that line blood vessels. It usually appears during the first weeks of life and resolves by age 10. In infancy, it is the most

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common tumor. The cause of hemangioma is currently unknown; however, several studies have suggested the importance of estrogen signaling in hemangioma proliferation.

Black Eye

A black eye (periorbital hematoma) or 'shiner', is bruising around the eye commonly due to an injury to the face rather than an eye injury. The name is given due to the color of bruising. The so-called black eye is caused by bleeding beneath the skin and around the eye. Sometimes a black eye indicates a more extensive injury, even a skull fracture, particularly if the area around both eyes is bruised (raccoon eyes) or if there has been a head injury.

Recording of Pulse in head and Neck region

Carotid Pulse: located in the neck (carotid artery). The carotid artery should be palpated gently and while the patient is sitting or lying down. Stimulating its baroreceptors with low palpitation can provoke severe bradycardia or even stop the heart in some sensitive persons. Also, a person's two carotid arteries should not be palpated at the same time. Doing so may limit the flow of blood to the head, possibly leading to fainting or brain ischemia. It can be felt between the anterior border of the sternocleidomastoid muscle, above the hyoid bone and lateral to the thyroid cartilage.

Facial pulse: located on the on a line with the corners of the mouth (facial artery).

Temporal pulse: located on the temporal region directly in front of the ear (superficial temporal artery).

Intracranial Hemorrhage

An intracranial hemorrhage is a hemorrhage, or bleeding, within the skull. Intracranial bleeding occurs when a blood vessel within the skull is ruptured or leaks. It can result from physical trauma (as occurs in head injury) or nontraumatic causes (as occurs in hemorrhagric stroke) such as a ruptured aneurysm. Anticoagulant therapy, as well as disorders with blood clotting can heighten the risk that an intracranial hemorrhage will occur. CT scan (computed tomography) is the definitive tool for accurate diagnosis of an intracranial hemorrhage.

Collateral Circulation

A process in which small arteries open up and connect two larger arteries or different parts of the same artery. Serve as alternate routes of blood supply. Collateral vessels grow and form a kind of "detour" around a blockage. The arteries of the scalp and the face anastomose freely so that the wounds of the face bleed profusely but heal quickly

Lymphatic Drainage

Introduction

Lymphatic System includes the lymphoid tissue and lymphatic vessels through which the lymph travels in a one-way system. Lymphoid tissue is found in many organs, particularly the lymph nodes, and in the lymphoid follicles such as the tonsils. The system also includes the spleen, thymus, bone marrow

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Functions

Lymphatic system removes interstitial fluid from tissues Absorbs and transports fatty acids and fats as chyle to the circulatory system Transports immune cells to and from the lymph nodes Transports antigen-presenting cells (apcs) to the lymph nodes where an immune

response is stimulated. Carries lymphocytes from the efferent lymphatics exiting the lymph nodes

Lymphoid tissue

The tissue consists of connective tissue with various types of white blood cells enmeshed in it, most of them are the lymphocytes. Depending upon the stage of lymphocyte development and maturation, It is classified into

Primary lymphoid tissue Secondary lymphoid tissue

Primary lymphoid organs Generate lymphocytes from immature progenitor cells. The organs are the thymus and the bone marrow

Secondary lymphoid organs Maintain mature naive lymphocytes and initiate an adaptive immune response Mature lymphocytes recirculate between the blood and the peripheral lymphoid

organs until they encounter their specific antigen. The organs are the lymph nodes, and the lymphoid follicles in tonsil, peyer's

patches, spleen, adenoids, etc.

Spleen

It is a part of the lymphatic system. It is approximately 11 centimeters (4.3 in) in length. It weighs 150 - 200 grams (5.3 - 7.1 oz.). It lies beneath the 9th to the 12th thoracic ribs. The celiac trunk is its main vascular supply as of the surrounding structures

Functions

The main function of the spleen is

Mechanical filtration of red blood cells. Reserve of monocytes Active immune response through humoral and cell-mediated pathways.

Tonsils

Tonsil represents the defense mechanism of first line against ingested or inhaled foreign pathogens.

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Waldeyers Tonsillar Ring

It is the lymphoid tissue ring located in the pharynx and to the back of the oral cavity. It was named after the nineteenth century German anatomist Heinrich Wilhelm Gottfried von Waldeyer-Hartz. The ring consists of (from superior to inferior):

Pharyngeal tonsil (also known as 'adenoids' when infected) Tubal tonsil (where Eustachian tube opens in the nasopharynx) Palatine tonsils (commonly called "the tonsils) Lingual tonsils

Thymus

The thymus is a bilobed, greyish organ located in the thoracic cavity just below the neck. Develop immature t-cells into immunocompetent t-cells. It reaches maximum weight (20 to 37 grams) by the time of puberty.

Lymph Node

A lymph node is a small ball-shaped organ of the immune

system, distributed widely throughout the body and

linked by lymphatic vessels. Lymph nodes are garrisons

of B, T, and other immune cells. Lymph nodes are found

all through the body, and act as filters or traps for foreign

particles. They are important in the proper functioning of

the immune system.

They become inflamed or enlarged in various conditions,

which may range from trivial, such as a throat infection,

to life-threatening such as cancers. It is used for cancer staging, which decides the treatment to

be employed, and for determining the prognosis.

Lymph nodes can also be diagnosed by biopsy whenever they are inflamed. Certain diseases

affect lymph nodes with characteristic consistency and location.

Function

Pathogens, or germs, can set up infections anywhere in the body. However, lymphocytes, a type

of white blood cell, will meet the antigens, or proteins, in the peripheral lymphoid organs, which

includes lymph nodes. The antigens are displayed by specialized cells in the lymph nodes. Naive

lymphocytes (meaning the cells have not encountered an antigen yet) enter the node from the

bloodstream, through specialized capillary venules. After the lymphocytes specialize they will

exit the lymph node through the efferent lymphatic vessel with the rest of the lymph. The

lymphocytes continuously recirculate the peripheral lymphoid organs and the state of the lymph

nodes depends on infection. During an infection, the lymph nodes can expand due to intense B-

cell proliferation in the germinal centers, a condition commonly referred to as "swollen glands".

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Development

The lymphatic vessels, lymph nodes, and spleen develop from lateral plate mesoderm.

The lymphatic system begins to develop by the end of the fifth week.

Lymph nodes of the head and neck

Submental Lymph Nodes

Lie on mylohyoid muscle in the submental triangle

2 to 8 in number

Afferents come from the chin, middle part of lower lip, anterior part of the mouth, lower

incisors

Efferents go to submandibular and internal jugular chain

Submandibular Lymph Nodes

lie in submandibular triangle in relation to submandibular gland.

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Afferents come from the lips, cheek, nasal vestibule and anterior part of nasal cavity,

gingiva, teeth, medial canthus, soft palate, anterior pillar, anterior part of tongue,

sublingual, submandibular and salivary glands and floor of mouth

Efferents go to internal jugular chain

Parotid Nodes

lie in relation to the parotid gland.

Afferents come from the scalp, pinna, external auditory canal, face, buccal mucosa.

Efferents go to internal jugular or external jugular chain

Postauricular Lymph Nodes

Also called as mastoid nodes

lie behind the the pinna over the mastoid.

Afferents come from the scalp, posterior surface of pinna and skin of mastoid.

Efferents drain into internal jugular chain

Occipital Lymph Nodes

They lie at the apex of the posterior triangle

Afferents come from scalp, skin of upper neck.

Efferents drain into upper accessory chain of nodes

Lateral Cervical Lymph Nodes

These include nodes, superficial and deep to sternocleidomastoid muscle and in the posterior

triangle.

Superficial external jugular group

Deep group

i. Internal jugular chain (upper, middle and lower groups)

ii. Spinal accessory chain

iii. Transverse cervical chain

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Internal Jugular Chain

Lymph nodes of internal jugular chain lie anterior, lateral and posterior to internal jugular

vein.

Upper group (jugulodigastric node) drains from oral cavity, orpharynx, nasopharynx,

hypopharynx, larynx and parotid.

Middle group drains from hypopharynx, larynx, throid, oral cavity, oropharynx.

Lower jugular group drains from larynx, thyroid and cervical oesophagus

Spinal Accessory chain

Lies along the spinal accessory nerve. Drains the scalp, skin of the neck, the

nasopharynx, occipital and postauricular nodes.

Efferents from this chain drain into transverse cervical chain

Examination of Head and neck Lymph nodes

Examination of neck nodes is important, particularly in head and neck malignancies.

Neck nodes are better palpated while standing at the back of the patient. Neck is slightly flexed

to achieve relaxation of muscles.

Points to be considered during examination of lymph nodes

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(i) Location of nodes

(ii) Number of nodes

(iii) Size of nodes

(iv) Consistency - Metastatic nodes are hard, lymphoma nodes are firm and rubbery

(v) Tenderness - Inflammatory nodes are tender.

(vi) Fixity to overlying skin or deeper structures. Mobility should be checked both in the

vertical and horizontal planes

Submental Lymph nodes

Roll the fingers below the chin with patients head tilted

forwards

Submandibular Lymph nodes

Roll fingers against inner surface of mandible with patient's

head gently tilted towards the side

Parotid (preauricular) Lymoh nodes

Roll finger in front of the ear, against the maxilla

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Post auricular (Mastoid) Nodes

Roll the fingers behind the ear

Intenal jugular Chain

Examine the upper, middle and lower groups. Many of

them lie deep to sternomastoid muscle

Transverse Cervical Nodes Supraclavicular (Scalene Nodes)

Roll fingers gently behind the clavicles. Ask the patient to

cough.

Lymphadenopathy

Lymphadenopathy is usually a normal response of the lymph nodes to an infection elsewhere in

the body. Lymphadenitis is an inflammation of the lymph nodes.

Causes of Lymphadenopathy

Infectious disease

Immunologic disease

Malignant disease

Hematological

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Metastasis

Lipid storage disease

Endocrine disease

Other disorder

Structures that can be mistaken for enlarged lymoh nodes

cystic hygromas

branchial cleft cysts

thyroglossal duct cysts

dental abscesses

dermoid cysts

tumors of thyroid or neural tissue

Summary

The blood, heart, and blood vessels form the cardiovascular system. The lymph, lymph nodes, and lymph vessels form the lymphatic system. The cardiovascular system and the lymphatic system together make up the circulatory system. The study of lymphatic drainage of various organs is important in diagnosis, prognosis, and treatment of cancer.

References

1. Richard L. Drake: Grays Anatomy for Students, 2nd ed. 2010, Churchill Livingstone

2. Richard S. Snell; Clinical Anatomy 4th ed., Lippincott

3. F. H. Netter; Atlas of Human Anatomy 4th ed, Elsevier

4. B.D. Chaurasia: Human Anatomy vol.3 5th ed., 2010 CBS Publishers

5. Keith L. Moore: Clinically Oriented Anatomy, 6th ed. 2009, Wolters Kluwer Pvt. Ltd.

6. Harold Ellis: Clinical Anatomy, 11th ed., 2006, Blackwell Publishing

7. M.K. Anand: Human Anatomy, 2nd ed., 2009 Arora Medical book publishers