Download - Blood Supply Seminar
-
1
-
2
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
-
3
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.
-
4
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.
-
5
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;
bmrSquiggly
bmrUnderline
-
6
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.
bmrHighlight
bmrHighlight
bmrHighlight
bmrHighlight
bmrHighlight
bmrHighlight
bmrHighlight
-
7
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
bmrHighlight
bmrHighlight
-
8
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.
bmrHighlight
-
9
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.
-
10
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
-
11
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
-
12
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.
-
13
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.
-
14
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
-
15
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
-
16
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
-
17
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.
-
18
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".
-
19
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.
-
20
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
-
21
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
-
22
(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
-
23
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
-
24
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