lymphatic drainage of head & neck

GOOD AFTERNOON

Lymphatic Drainage of Head & Neck

Presented by :-Dr. Manish Kumar

Contents :-IntroductionHistorical Perspective & Current ViewEmbryological DevelopmentFunctions of Lymphatic SystemComponents of Lymphatic SystemLymph Nodes of Head & NeckLymphatic Drainage Applied AspectsLymph-adenopathyClinical AssessmentLaboratory InvestigationsDifferential DiagnosisConclusion

Introduction - Of all the body systems, the lymphatic system is perhaps the least familiar to most people. Yet without it, neither the circulatory system nor the immune system could function—circulation would shut down from fluid loss, and the body would be overrun by infection for lack of immunity.

The lymphatic system is an endothelium-lined network of blind-ended capillaries found in nearly all tissues, draining via collecting vessels into large vascular trunks that eventually empty via an evolutionarily conserved drainage point into the blood circulatory system.

Birth Defects Res C Embryo Today. 2009 September ; 87(3): 222–231. doi:10.1002/bdrc.20155.

The lymphatic system.(A) Schematic illustration of the human lymphatic vascular system. (B) Structure of lymphatic vessels. (C) Schematic representation of a lymph node. (D) Connection of the lymphatic system with the blood vasculature at the subclavian veins.

Historical Perspective -

Hippocrates first described vessels containing “white blood” around 400 B.C.

Gasparo Aselli re-identified lymphatic vessels in the 1600’s, noting the presence of lipid-filled “milky veins” in the gut of a “well-fed” dog (Aselli, 1627).

Historically, the most widely accepted view of lymphatic development was proposed by Sabin in the early twentieth century (Sabin 1902, 1904).



Sabin’s Model :The isolated primitive lymph sacs originate from endothelial cells that bud from the veins during early development.

The two jugular lymph sacs were proposed to develop in the junction of the sub-clavian and anterior cardinal veins by endothelial budding from the anterior cardinal veins.

The remaining lymph sacs originate from the mesonephric vein and those in the dorsomedial edge of the Wolffian bodies in the junction of the subclavian and anterior cardinal veins.

GENES & DEVELOPMENT 16:773–783 © 2002 by Cold Spring Harbor Laboratory Press ISSN 0890-9369

Historical Perspective - The retroperitoneal lymph sac forms near the primitive inferior vena cava and mesonephric veins; the cisterna chyli forms near the Wolffian bodies; and the posterior lymph sacs appear near the junctions of the primitive iliac veins and the posterior cardinal veins.

The peripheral lymphatic system originates from the primary lymph sacs, then spreads by endothelial sprouting into the surrounding tissues and organs, where local capillaries are formed.



Schematic representation of the primitive lymphatic system showing the primary lymph sacs in a 42-day-old human embryo, after Sabin (reprinted from Human Embryology, by W.J. Larsen, 1993, Harcourt, NY; with permission from Harcourt International).



Alternative Model / Centripetal Model :-proposed by Huntington and McClure 1910.

They suggested that the primary lymph sacs arise in the mesenchyme, independent of the veins, and secondarily establish venous connections.

This model was supported by Schneider et al. 1999.

GENES & DEVELOPMENT 16:773–783 © 2002 by Cold Spring Harbor Laboratory Press ISSN 0890-9369Birth Defects Res C Embryo Today. 2009 September ; 87(3): 222–231. doi:10.1002/bdrc.20155.


Perhaps the most definitive evidence for a venous origin for early lymphatic endothelial cells has come from the zebra fish (Yaniv et al., 2006).

Recent studies have shown that the zebra fish possesses a lymphatic vascular system with many of the morphological, molecular, and functional characteristics of the lymphatic's of other vertebrates.


Current View - There are several markers that show different profiles of expression in blood and lymphatic vasculature, e.g. :-

Vascular endothelial growth factor receptor – 3 (VEGFR-3 / Flt-4)Lymphatic endothelial hyaluronan receptor - 1 (LYVE – 1; a CD44 homolog)Secondary lymphoid chemokine (SLC / 6C Kine / Exodus-2 / CCL21)Podoplanin; a surface glycoproteinDesmoplakin; a cytoplasmic proteinProx-1 (prospero-related homeobox 1)


Current View -

All venous endothelial cells are initially bi-potent and the expression of at least Prox-1 gene causes those cells to initiate the program of lymphatic differentiation.

As the development proceeds, the sub-population of LYVE-1 and Prox-1 positive cells start to bud from the veins in an initially Prox-1 independent manner; however maintenance of the budding requires Prox-1 activity.

As the cells bud they start to express higher levels of additional markers such as SLC and VEGFR-3.


Current View - The expression of Prox-1, LYVE-1,SLC and VEGFR-3 may indicate that the cells are irreversibly committed to the lymphatic pathway.


Current View :-

Recent studies indicate that Sox18 controls expression of Prox1 (Francois et al., 2008).

SOX18, an SRY-related HMG domain transcription factor, was implicated in lymphatic development by the identification of SOX18 mutations in individuals with hypotrichosis-lymphedema-telangiectasia syndrome (Irrthum et al., 2003).

Lentiviral expression of Sox18 in both differentiating Embryonic stem cells (ES cells) and blood vascular endothelial cells induced expression of Prox1 and Podoplanin (Francois et al., 2008).

Birth Defects Res C Embryo Today. 2009 September ; 87(3): 222–231. doi:10.1002/bdrc.20155

Current View :-

At embryonic day (E) 9.0 in mice and gestation week 6 in humans, after arterial-venous separation, cells of the cardinal vein start to lose blood endothelial characteristics and acquire a lymphatic endothelial cell (LEC) identity. This process is controlled by the sequential expression of Lyve-1, Sox18 and Prox1.

Int. J. Dev. Biol.2011;55:483-494 doi: 10.1387/ijdb.103226ia

Current View :-

At E10.5, LEC then bud off the cardinal vein, migrate into the surrounding tissue and form primary lymphatic sacs. This process is dependent on VEGF-C/VEGFR3/Nrp2 signaling. Subsequently, the primary lymphatic sacs separate from the cardinal vein and by further growth and spreading into the tissue, gives rise to a primitive lymphatic plexus.


Current View :-

At E14.5, remodeling of the primitive lymphatic vasculature begins and lasts until after birth.


Current View :-

During this period a hierarchical network consisting of collecting lymphatic vessels and lymphatic capillaries are formed.

This maturation process involves changes in protein expression leading to a quiescent, non-growing vessel, the formation of lymphatic valves and the acquisition of a smooth muscle coat.

With the accumulation of basement membrane proteins at E16.5 recruitment of NG2-positive mural cells begins to finally generate the smooth muscle cell coverage observed in major lymphatic vessels (Norrmen et al., 2009).


Embryological Development -The lymphatic system begins to develop at the end of week 5, approximately 2 weeks later than the cardiovascular system.

IN WEEKS 6-9, local dilatations of the lymphatic channels and formation of 6 primary lymph sacs occurs.

Two jugular lymph sacs near the junction of the subclavian veins with the anterior cardinals (future internal jugular vein)Two iliac lymph sacs near the junction of the iliac veins with the posterior cardinal veinsOne retroperitoneal lymph sac in the root of the mesentery on the posterior abdominal wallOne cisterna chyli dorsal to the retroperitoneal lymph sac, at the level of the adrenal glands

EMBRYONIC DEVELOPMENT & STEM CELL COMPENDIUM; LIFE MAP DISCOVERY.

Embryological Development -

Lymph vessels development –it grows from the lymph sacs, along the major veins,to the head, neck, and arms from the jugular sacs;to the lower trunk and legs from the iliac sacs; andto the gut from the retroperitoneal and cisternal sacs.

EMBRYONIC DEVELOPMENT & STEM CELL COMPENDIUM; LIFE MAP DISCOVERY.Embryology Atlas ; Chapter 23: Lymphatic System; Embryological Development by John F. Neas

Thoracic Duct -

The cisterna chyli is connected to the jugular lymph sacs by 2 large channels, the right and left thoracic ducts.

An anastomosis forms between the 2 ducts, thus, the definitive thoracic duct is formed by the caudal portion of the right thoracic duct, the anastomosis, and the cranial portion of the left thoracic duct.

The right lymphatic duct is derived from the cranial part of the right thoracic duct.

EMBRYONIC DEVELOPMENT & STEM CELL COMPENDIUM; LIFE MAP DISCOVERY

Thoracic Duct -

Both the right and left thoracic ducts join the venous system at the angle of the subclavian and internal jugular veins at the base of the neck

Embryological Development -

Lymph node development, at about month 3.

Except for the anterior part of the sac that produces the cisterna chyli, all lymphatic capillary plexuses become invaded by mesenchymal cells that proliferate and aggregate to form groups of lymph nodes.

The lymph nodule and germinal centers of lymphocyte production do not appear in the nodes until just before or after birth


Other lymphatic tissues -

SPLEEN –

It develops from an aggregation of mesenchymal cells in the dorsal mesentery of the stomach.

Development involves establishment of mesenchymal trabeculae within a blood vascular network consisting of a large number of endothelial sinuses.



THYMUS – It arises as endodermal diverticula of the ventral part of the third pharyngeal pouches.

The two thymic diverticula grow inferiorly in the neck to reach the superior mediastinum and fuse into a two-lobed organ.

The thymus achieves maximum size at puberty and gradually regresses thereafter, being replaced by fatty tissue.



TONSILS – The palatine tonsils form from the second pair of pharyngeal pouches

The tubal (pharyngotympanic) tonsils develop from aggregations of lymph nodules around the openings of the auditory tubes

The pharyngeal tonsils (adenoids) develop from an aggregation of lymph nodules in the nasopharyngeal wall

The lingual tonsils develop from aggregations of lymph nodules in the root of the tongue


Functions of Lymphatic System -

The lymphatic system has three functions:

Fluid recovery.

Immunity

Lipid absorption

The lymphatic vessels of the small intestine receive the special designation of lacteals or chyliferous vessels.

Anatomy and physiology - The unity of form and function (Saladin K. - 2003 - 3rd ed. - McGraw-Hill)

The main functions of the lymphatic system are as follows:to collect and transport tissue fluids from the intercellular spaces in all the tissues of the body, back to the veins in the blood system;

it plays an important role in returning plasma proteins to the bloodstream;

digested fats are absorbed and then transported from the villi in the small intestine to the bloodstream via the lacteals and lymph vessels.

new lymphocytes are manufactured in the lymph nodes;

Lymphocytes attack a cancer cell.

antibodies and lymphocytes assist the body to build up an effective immunity to infectious diseases;

lymph nodes play an important role in the defence mechanism of the body. They filter out micro-organisms (such as bacteria) and foreign substances such as toxins, etc.

it transports large molecular compounds (such as enzymes and hormones) from their manufactured sites to the bloodstream.

Components of Lymphatic system -

The components of the lymphatic system are :- Lymph, the recovered fluid;

Lymphatic vessels, which transport the lymph;

Lymphatic tissue, composed of aggregates of lymphocytes and macrophages that populate many organs of the body; and

lymphatic organs, in which these cells are especially concentrated and which are set off from surrounding organs by connective tissue capsules.


Lymph - Lymph is usually a clear, colorless fluid, similar to blood plasma but low in protein. Its composition varies substantially from place to place.

Origin of Lymph :-

Lymph originates in microscopic vessels called lymphatic capillaries. These vessels penetrate nearly every tissue of the body but are absent from the central nervous system, cartilage, bone, and bone marrow.

The gaps between lymphatic endothelial cells are so large that bacteria and other cells can enter along with the fluid.


Lymph -

Origin of Lymph :-

The overlapping edges of the endothelial cells act as valve like flaps that can open and close.

When tissue fluid pressure is high, it pushes the flaps inward (open) and fluid flows into the lymphatic capillary. When pressure is higher in the lymphatic capillary than in the tissue fluid, the flaps are pressed outward (closed).


Lymphatic Capillaries. (a) Relationship of the lymphatic capillaries to a bed of blood capillaries. (b) Uptake of tissue fluid by a lymphatic capillary.


Lymphatic Vessels :-

They have a tunica interna with an endothelium and valve, a tunica media with elastic fibers and smooth muscle, and a thin outer tunica externa.

Their walls are thinner and their valves are more numerous than those of the veins.


Flow of Lymph :-Lymph takes the following route from the tissues back to the bloodstream:

lymphatic capillaries -> collecting vessels ->

six lymphatic trunks -> two collecting ducts ->

subclavian veins.

Thus, there is a continual recycling of fluid from blood to tissue fluid to lymph and back to the blood


Mechanism of lymphatic flow :-Lymph flows under forces similar to those that govern venous return, except that the lymphatic system has no pump like the heart.

Lymph flows at even lower pressure and speed than venous blood; it is moved primarily by rhythmic contractions of the lymphatic vessels themselves, which contract when stretched by lymph.

The lymphatic vessels, like the veins, are also aided by a skeletal muscle pump that squeezes them and moves the lymph along.

Also like the medium veins, lymphatic vessels have valves that prevent lymph from flowing backward.

Since lymphatic vessels are often wrapped with an artery in a common sheath, arterial pulsation may also rhythmically squeeze the lymphatic vessels and contribute to lymph flow.

A thoracic (respiratory) pump aids the flow of lymph from the abdominal to the thoracic cavity as one inhales, just as it does in venous return.

Finally, at the point where the collecting ducts join the subclavian veins, the rapidly flowing bloodstream draws the lymph into it.

Considering these mechanisms of lymph flow, it should be apparent that physical exercise significantly increases the rate of lymphatic return.

Lymphatic Cells and Tissues :-

T lymphocytes (T cells). These are so-named because they develop for a time in the thymus and later depend on thymic hormones. There are several subclasses of T cells.

B lymphocytes (B cells). These are named after an organ in birds (the bursa of Fabricius) in which they were first discovered. When activated, B cells differentiate into plasma cells, which produce circulating antibodies, the protective gamma globulins of the body fluids.


T Cells “Inspecting” Macrophages in a Lymph Node for Antigen Presentation. From R. G. Kessel and R. H. Kardon, Tissues and Organs: A Text-Atlas of Scanning Electron Microscopy (W. H. Freeman & Co., 1979).



Macrophages. These cells, derived from monocytes of the blood, phagocytize foreign matter (antigens) and “display” fragments of it to certain T cells, thus alerting the immune system to the presence of an enemy. Macrophages and other cells that do this are collectively called antigen-presenting cells (APCs).

Dendritic cells. These are APCs found in the epidermis, mucous membranes, and lymphatic organs. (In the skin, they are often called Langerhans cells.)


The Action of an Antigen-Presenting Cell (APC). (a) Stages in the processing and presentation of an antigen by an APC such as a macrophage. (b) Macrophages phagocytizing bacteria. Filamentous extensions of the macrophage snare the rod-shaped bacteria and draw them to the cell surface, where they are engulfed.



Reticular cells. These are branched cells that contribute to the stroma (connective tissue framework) of the lymphatic organs and act as APCs in the thymus.


Mucosa-associated lymphatic tissue.

The simplest form of lymphatic tissue is diffuse lymphatic tissue—a sprinkling of lymphocytes in the mucous membranes and connective tissues of many organs.

It is particularly prevalent in body passages that are open to the exterior—the respiratory, digestive, urinary, and reproductive tracts—where it is called mucosa-associated lymphatic tissue (MALT).

Lymphatic Cells and Tissues :-Peyers patches.In some places, lymphocytes and other cells congregate in dense masses called lymphatic nodules (follicles).Lymphatic nodules are, however, a relatively constant feature of the lymph nodes and tonsils.They also form clusters called Peyers patches in the ileum, the last segment of the small intestine.

Lymphatic Organs -

Understanding Human Anatomy and Physiology - Sylvia S. Mader

Lymphatic Organs -

Primary Lymphatic Organs :-

Lymphatic (lymphoid) organs contain large numbers of lymphocytes, a type of white blood cell that plays a pivotal role in immunity.

The primary lymphatic organs arethe red bone marrow andthe thymus gland.

Lymphocytes originate and/or mature in these organs.

Understanding Human Anatomy and Physiology - Sylvia S. Mader

Primary Lymphatic Organs :-

Red Bone Marrow

It is the site of stem cells that are ever capable of dividing and producing blood cells.

Some of these cells become the various types of white blood cells: neutrophils, eosinophils, basophils, lymphocytes, and monocytes.

In a child, most of the bones have red bone marrow, but in an adult it is limited to the sternum, vertebrae, ribs, part of the pelvic girdle, and the proximal heads of the humerus and femur.

Red Bone Marrow :-

Red bone marrow is the site of stem cells that are ever capable of dividing and producing blood cells. Some of these cells become the various types of white blood cells:

neutrophils, eosinophils, basophils, lymphocytes, and monocytes .

In a child, most bones have red bone marrow, but in an adult it is limited to the sternum, vertebrae, ribs, part of the pelvic girdle, and the proximal heads of the humerus and femur.

Red Bone Marrow :-

The red bone marrow consists of a network of reticular tissue fibers, which support the stem cells and their progeny.

They are packed around thin-walled sinuses filled with venous blood. Differentiated blood cells enter the bloodstream at these sinuses.

Lymphocytes differentiate into the B lymphocytes and the T lymphocytes.

Bone marrow is not only the source of B lymphocytes, but also the place where B lymphocytes mature.

T lymphocytes mature in the thymus.

Thymus :-The thymus is a member of both the lymphatic and endocrine systems.

It houses developing lymphocytes and secretes hormones that regulate their activity.

It is located between the sternum and aortic arch in the superior mediastinum.

The thymus is very large in the fetus and grows slightly during childhood, when it is most active.

After age 14, however, it begins to undergo involution (shrinkage) so that it is quite small in adults.

Thymus :-

In the elderly, the thymus is replaced almost entirely by fibrous and fatty tissue and is barely distinguishable from the surrounding tissues.

Reticular epithelial cells secrete hormones called thymosins, thymulin, and thymopoietin, which promote the development and action of T cells.

If the thymus is removed from newborn mammals, there will be lack of immunity development.

Secondary Lymphatic Organs :-

The secondary lymphatic organs arethe spleen,the lymph nodes and other organs, such as the tonsils, Peyer patches, and the appendix.

All the secondary organs are the places where lymphocytes encounter and bind with antigens, after which they proliferate and become actively engaged cells.

Spleen :-The spleen is the body’s largest lymphatic organ. It is located in the left hypochondriac region, just inferior to the diaphragm and dorsolateral to the stomach.

It has a medial hilum penetrated by the splenic artery and vein and lymphatic vessels.

Its parenchyma exhibits two types of tissue named for their appearance in fresh specimens (not in stained sections):

red pulp, which consists of sinuses gorged with concentrated erythrocytes, andwhite pulp, which consists of lymphocytes and macrophages aggregated like sleeves along small branches of the splenic artery.

The Spleen. (a) Position of the spleen in the upper left quadrant of the abdominal cavity. (b) Histology.

Spleen :-Functions –

It produces blood cells in the fetus and may resume this role in adults in the event of extreme anemia.

It monitors the blood for foreign antigens, much like the lymph nodes do the lymph.

Lymphocytes and macrophages of the white pulp are quick to detect foreign antigens in the blood and activate immune reactions.

Spleen :-

The spleen is an “erythrocyte graveyard”—old, fragile RBCs rupture as they squeeze through the capillary walls into the sinuses. Splenic macrophages phagocytize their remains, just as they dispose of blood-borne bacteria and other cellular debris.

The spleen also compensates for excessive blood volume by transferring plasma from the bloodstream into the lymphatic system.

A person can live without a spleen, but is somewhat more vulnerable to infections.

Lymph Nodes :-

Lymph nodes serve two functions:to cleanse the lymph and alert the immune system to pathogens.

There are hundreds of lymph nodes in the body.

They are especially concentrated in the cervical, axillary, and inguinal regions close to the body surface, and in thoracic, abdominal, and pelvic groups deep in the body cavities.

Most of them are embedded in fat.

Lymph Nodes :-Structure –A lymph node is an elongated or bean-shaped structure, usually less than 3 cm long, often with an indentation called the hilum on one side.

It is enclosed in a fibrous capsule with extensions (trabeculae) that incompletely divide the interior of the node into compartments.

The interior consists of a stroma of reticular connective tissue (reticular fibers and reticular cells) anda parenchyma of lymphocytes and antigen-presenting cells.

Anatomy of a Lymph Node. (a) Bisected lymph node showing pathway of lymph flow.(b) Detail of the boxed region in a.

Anatomy of a Lymph Node - Stroma and immune cells in a medullary sinus.

Lymph Nodes :-Between the capsule and parenchyma is a narrow space called the subcapsular sinus, which contains reticular fibers, macrophages, and dendritic cells.

The parenchyma is divided into an outer cortex and, near the hilum, an inner medulla.

The cortex consists mainly of ovoid lymphatic nodules.

When the lymph node is fighting a pathogen, these nodules acquire light-staining germinal centers where B cells multiply and differentiate into plasma cells.

Lymph Nodes :-The medulla consists largely of a branching network of medullary cords composed of lymphocytes, plasma cells, macrophages, reticular cells, and reticular fibers.

The lymph node is a “bottleneck” that slows down lymph flow and allows time for cleansing it of foreign matter.

The macrophages and reticular cells of the sinuses remove about 99% of the impurities before the lymph leaves the node.

On its way to the bloodstream, lymph flows through one lymph node after another and thus becomes quite thoroughly cleansed of most impurities.

Tonsils :-

The tonsils are patches of lymphatic tissue located at the entrance to the pharynx, where they guard against ingested and inhaled pathogens.

Each is covered by an epithelium and has deep pits called tonsillar crypts lined by lymphatic nodules.

The crypts often contain food debris, dead leukocytes, bacteria, and antigenic chemicals.

Below the crypts, the tonsils are partially separated from underlying connective tissue by an incomplete fibrous capsule.

Tonsils :-There are three main sets of tonsils:

a single medial pharyngeal tonsil (adenoids) on the wall of the pharynx just behind the nasal cavity,

a pair of palatine tonsils at the posterior margin of the oral cavity, and

numerous lingual tonsils, each with a single crypt, concentrated in a patch on each side of the root of the tongue.

The palatine tonsils are the largest and most often infected.

Tertiary lymphoid organs/tissues -

Ectopic or tertiary lymphoid tissues develop at sites of inflammation or infection in peripheral, non-lymphoid organs.

These tissues are architecturally similar to conventional secondary lymphoid organs, with separated B and T cell areas, specialized populations of dendritic cells, well-differentiated stromal cells and high endothelial venules.

Most important of these sites are those tissues with direct contact with the “external” environment, primarily the skin and mucosal lining of the gastrointestinal, pulmonary, and genitourinary tracts.

Semin Immunol. 2008 February; 20(1): 26–42.Ann Rheum Dis 2010;69(Suppl 2):A1–A76

http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=18243731




LYMPHATIC DRAINAGE OF HEAD & NECK :-Lymph nodes in the head and neck are arranged in two horizontal rings and two vertical chains on either side of the neck.

The outer, superficial, ring consists of the occipital, preauricular (parotid), submandibular and submental nodes, and the inner, deep, ring is formed by clumps of mucosa associated lymphoid tissue (MALT) located primarily in the naso- and oro-pharynx (Waldeyer's ring).

Waldeyer's ring -

Waldeyer's tonsillar ring, consisting of an unpaired pharyngeal tonsil in the roof of the pharynx, paired palatine tonsils and lingual tonsils scattered in the root of the tongue. (Modified from Kahle et al. Color Atlas and Textbook of Human Anatomy).

LYMPHATIC DRAINAGE OF HEAD & NECK :-

The vertical chain consists of superior and inferior groups of nodes related to the carotid sheath.

All lymph vessels of the head and neck drain into the deep cervical nodes, either directly from the tissues or indirectly via nodes in outlying groups.

Lymph is returned to the systemic venous circulation via either the right lymphatic duct or the thoracic duct.

Classification :-Node Location Afferent Efferent

Superficial Lymph Nodes of the Head

Occipital (2-4) Superior nuchal line between sternocleidomastoid and trapezius

Occipital part of scalp Superficial cervical lymph nodesAccessary lymph nodes

Mastoid (1-3) Superficial to sternocleidomastoid insertion

Posterior parietal scalpSkin of ear, posterior external acoustic meatus

Superior deep cervical nodes Accessary lymph nodes

Preauricular (2-3) Anterior to ear over parotid fascia

Drains areas supplied by superficial temporal arteryAnterior parietal scalpAnterior surface of ear

Superior deep cervical lymph nodes

Textbook of Head and Neck Anatomy (Hiatt - Gartner, 4th Ed. 2010)

Parotid (up to 10 or more)

About parotid gland and under parotid fasciaDeep to parotid gland

External acoustic meatusSkin of frontal and temporal regionsEyelids, tympanic cavityCheek, nose (posterior palate)


FacialSuperficial(up to 12)MaxillaryBuccalMandibular

Distributed along course of facial artery and vein

Skin and mucous membranes of eyelids, nose, cheek

Submandibular nodes

Deep Distributed along course of maxillary artery lateral to lateral pterygoid muscle

Temporal and infratemporal fossaNasal pharynx



Cervical Lymph NodesSuperficial Anterior jugular vein

between superficial cervical fascia and infrahyoid fascia

Skin, muscles, and viscera of infrahyoid region of neck


Deep Between viscera of neck and investing layer of deep cervical fascia

Adjoining parts of trachea, larynx, thyroid gland


Anterior cervical/SuperficialSubmental (2-3) Submental triangle Chin

Medial part of lower lipLower incisor teeth and gingivaTip of tongueCheeks

Submandibular lymph node to jugulo-omohyoid lymph node and superior deep cervical lymph nodes


Submandibular (3-6)

Submandibular triangle adjacent to submandibular gland

Facial nodesChinLateral upper and lower lipsSubmental nodesCheeks and nose, anterior nasal cavityMaxillary and mandibular teeth and gingivaOral palateLateral parts of anterior 2/3 of tongue

Superior deep cervical lymph nodes and jugulo-omohyoid lymph nodes

Superficial cervical (1-2)

Along external jugular vein superficial to sternocleidomastoid muscle

Lower part of ear and parotid region



Deep Cervical Lymph Nodes

Superior deep cervical

Surrounding internal jugular vein deep to sternocleidomastoid and superior to omohyoid muscle

Occipital nodesMastoid nodesPreauricular nodesParotid nodesSubmandibular nodesSuperficial cervical nodesRetropharyngeal nodes

Inferior deep cervical nodes or separate channel to jugulo-subclavian junction

Jugulodigastric Junction of internal jugular vein and posterior digastric muscle

Palatine and lingual tonsilsPosterior palateLateral portions of the anterior 2/3 of tongue

Inferior deep cervical lymph nodes


Jugulo-omohyoid Above junction of internal jugular vein and omohyoid muscle

Posterior 1/3 of tongueSubmandibular nodesSubmental nodes

Inferior deep cervical lymph nodes

Inferior deep cervical

Along internal jugular vein below omohyoid muscle deep to the sternocleidomastoid muscle

Transverse cervical nodesAnterior cervical nodesSuperior deep cervical nodes

Jugular trunk

Retropharyngeal (1-3)

Retropharyngeal space

Posterior nasal cavityParanasal sinusesHard and soft palateNasopharynx, oropharynxAnditory tube

Superior deep cervical nodes


Accessory (2-6) Along accessory nerve in posterior triangle

Occipital nodesMastoid nodesLateral neck and shoulder

Transverse cervical nodes

Transverse cervical (1-10)

Along transverse cervical blood vessels at level of clavicle

Accessory nodesApical axillary nodesLateral neckAnterior thoracic wall

Jugular trunk or directly into thoracic duct or right lymphatic duct or independently into junction of internal jugular vein and subclavian vein


Level I The sub-mental and sub-mandibular nodes.They lie above the hyoid bone, below the mylohoid muscle and anterior to the back of the sub-mandibular gland.

Level IA The sub-mental nodes.They lie between the medial margins of the anterior bellies of the diagastric muscles.

Level IB The sub-mandibular nodes.On each side, they lie lateral to the level IA nodes and anterior to the back of each sub-mandibular gland.

Imaging-based nodal classification :-

1998 modification of the 1991 AAO-HNS (American Academy of Otolaryngology – Head and Neck Surgery) classification

Arch Otolaryngol Head Neck Surg. 1999;125:388-396.

Level II The upper internal jugular nodes.They extend from the skull base to the level of the bottom of the body of hyoid bone. They are posterior to the back of the sub-mandibular gland and anterior to the back of sternocleidomastoid muscle.

Level IIA A level II node that lies either anterior, medial, lateral or posterior to the internal jugular vein. If posterior to the vein, the node is inseparable from the vein.

Level IIB A level II node that lies posterior to the internal jugular vein and has a flat plane separating it and the vein.


Level III The middle jugular nodes.They extend from the level of the bottom of the body of the hyoid bone to the level of the bottom of the cricoid arch.They lie anterior to the back of sternocleidomastoid muscle.

Level IV The low jugular nodes.They extend from the level of the bottom of the cricoid arch to the level of the clavicle.They lie anterior to a line connecting the back of the sternocleidomastoid muscle and the posterolateral margin of the anterior scalene muscle.They are also lateral to the carotid arteries.


Level V The nodes in the posterior triangle.They lie posterior to the back of the sternocleidomastoid muscle from the skull base to the level of the bottom of the anterior scalene muscle from the level of the bottom of the cricoid arch to the level of the clavicle.They also lie anterior to the anterior edge of the trapezius muscle.

Level VA Upper level V nodes extend from the skull base to the level of the bottom of the cricoid arch.

Level VB Lower level V nodes extend from the level of the bottom of the cricoid arch to the level of the clavicle.

Level VI The upper visceral nodes.They lie between the carotid arteries from the level of the bottom of the body of the hyoid bone to the level of the top of the manubrium.


Level VII The superior mediastinal nodes.They lie between the carotid arteries below the level of the top of the manubrium and above the level of the innominate vein.

Supraclavicular nodes They lie at or caudal to the level of the clavicle and lateral to the carotid artery on each side of the neck.

Retropharyngeal nodes Within 2 cm of the skull base, they lie medial to the internal carotid arteries.


Lymph drainage of external noseLymph drainage of external nose is primarily to the submandibular group of nodes although lymph from the root of the nose drains to superficial parotid nodes.

Lymphatic drainage of nasal cavity

Lymph vessels from the anterior region of the nasal cavity pass superficially to join those draining the external nasal skin, and end in the submandibular nodes.

The rest of the nasal cavity, paranasal sinuses, nasopharynx and pharyngeal end of the pharyngotympanic tube, all drain to the upper deep cervical nodes either directly or through the retropharyngeal nodes.

The posterior nasal floor probably drains to the parotid nodes.

Lymphatic drainage of tongue -

The lymphatic drainage of the tongue can be divided into three main regions, marginal, central and dorsal.

The anterior region of the tongue drains into marginal and central vessels, and the posterior part of the tongue behind the circumvallate papillae drains into the dorsal lymph vessels.

The more central regions drain bilaterally into sub-mental and sub-mandibular nodes.

Lymphatic drainage of teeth -

The lymph vessels from the teeth usually run directly into the ipsi-lateral submandibular lymph nodes.

Lymph from the mandibular incisors, however, drains into the submental lymph nodes.

Occasionally, lymph from the molars may pass directly into the jugulo-digastric group of nodes.

Applied aspects -When a lymph node is under challenge from a foreign antigen, it may become swollen and painful to the touch— a condition called lymphadenitis.

Commonly palpated and accessible lymph nodes are - the cervical, axillary, and inguinal.

Lymph nodes are common sites of metastatic cancer because cancer cells from almost any organ can break loose, enter the lymphatic capillaries, and lodge in the nodes.

Lymphadenopathy is a collective term for all lymph node diseases

Block dissection of the neck -

Treatment for malignant disease is the removal of the lymph nodes of the anterior and posterior triangles of the neck and their associated lymph channels, together with those structures which must be excised in order to make this lymphatic ablation possible.

Tuberculous disease of the neck -

Usually involves the upper part of the deep cervical chain (from tonsillar infection).

These infected nodes may adhere very firmly to the internal jugular vein which may be wounded in the course of their excision.

Spread of supra- and subglottic tumours -

The upper deep cervical lymph nodes act as pathways of spread for malignant tumours of the supraglottic larynx: up to 40% of these tumours will have undergone such spread at the time of clinical presentation.

The glottis is very poorly endowed with lymphatic vessels: 95% of malignant tumours confined to the glottis will present with a change in voice or airway obstruction but will not show signs of spread to adjacent lymph nodes at presentation.

Spread of supra- and subglottic tumours -

Tumours of the subglottic larynx will often spread to the paratracheal lymph node chain prior to clinical presentation.

However, the presenting symptoms may be voice change and airway obstruction rather than a mass in the neck, because the paratracheal lymph nodes occupy a deep-seated position in the root of the neck and so their enlargement may remain occult.

Lymphadenopathy -

Lymphadenopathy - enlargement of the lymph nodes.

It may be an incidental finding in patients being examined for various reasons, or it may be a presenting sign or symptom of the patient's illness.

Soft, flat, submandibular nodes (<1 cm) are often palpable in healthy children and young adults;

Healthy adults may have palpable inguinal nodes of up to 2 cm, which are considered normal.

Generalized lymphadenopathy

It has been defined as involvement of three or more noncontiguous lymph node areas.

Generalized lymphadenopathy is frequently associated with nonmalignant disorders such as

infectious mononucleosis [Epstein-Barr virus (EBV) or cytomegalovirus (CMV)],toxoplasmosis, AIDS, other viral infections,systemic lupus erythematosus (SLE), andmixed connective tissue disease.

Acute and chronic lymphocytic leukemias and malignant lymphomas also produce generalized adenopathy in adults.

Localized or regional lymphadenopathy

implies involvement of a single anatomic area.

The site of localized or regional adenopathy may provide a useful clue about the cause.

e.g. Occipital adenopathy often reflects an infection of the scalp, and preauricular adenopathy accompanies conjunctival infections and cat-scratch disease.

Diseases Associated with Lymphadenopathy – Etiological classification

Infectious diseasesViral infectious mononucleosis syndromes (EBV, CMV), infectious

hepatitis, herpes simplex, herpesvirus-6, varicella-zoster virus, rubella, measles, adenovirus, HIV, epidemic keratoconjunctivitis, vaccinia, herpesvirus-8

Bacterial streptococci, staphylococci, cat-scratch disease, brucellosis, tularemia, plague, chancroid, melioidosis, glanders, tuberculosis, atypical mycobacterial infection, primary and secondary syphilis, diphtheria, leprosy

Fungal histoplasmosis, coccidioidomycosis, paracoccidioidomycosis

Chlamydial lymphogranuloma venereum, trachoma

Parasitic toxoplasmosis, leishmaniasis, trypanosomiasis, filariasis

Rickettsia scrub typhus, rickettsialpox, Q fever

Immunologic diseases Rheumatoid arthritis Juvenile rheumatoid arthritis Mixed connective tissue disease Systemic lupus erythematosus Dermatomyositis Sjögren's syndrome Serum sickness Drug hypersensitivity—diphenylhydantoin, hydralazine, allopurinol, primidone, gold, carbamazepine, etc. Angioimmunoblastic lymphadenopathy Primary biliary cirrhosis Graft-vs.-host disease Silicone-associated Autoimmune lymphoproliferative syndrome

Malignant diseasesHematologic—Hodgkin's disease, non-Hodgkin's lymphomas, acute or chronic lymphocytic leukemia, hairy cell leukemia, malignant histiocytosis, amyloidosisMetastatic—from numerous primary sites

Lipid storage diseases—Gaucher's, Niemann-Pick, Fabry, Tangier

Endocrine diseases—hyperthyroidism, Adrenal insufficiency, Thyroiditis.

Other disorders Castleman's disease (giant lymph node hyperplasia) Sarcoidosis Dermatopathic lymphadenitis Lymphomatoid granulomatosis Histiocytic necrotizing lymphadenitis (Kikuchi's disease) Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) Mucocutaneous lymph node syndrome (Kawasaki's disease) Histiocytosis X Familial Mediterranean fever Severe hypertriglyceridemia Vascular transformation of sinuses Inflammatory pseudotumor of lymph node Congestive heart failureAbbreviations: CMV, cytomegalovirus; EBV, Epstein-Barr virus.

Lymphadenopathy – classification depending upon the clinical presentation.

Presentation Common Uncommon Rare Acute Unilateral

-Staphylococcus aureus -Group A streptococcus -Anaerobic bacteria

-Group B streptococcus -Tularemia1 -Pasturella multocida -Gram negative bacteria -Yersinia pestis

-Anthrax

Acute Bilateral

-Numerous common upper respiratory tract viruses -Herpes Simplex Virus -Epstein-Barr virus1,2 -Cytomegalovirus1,2 -Group A streptococcus -Mycoplasma pneumoniae

-Roseola 2 -Parvovirus B19

Corynebacterium diphtheriae -Measles -Mumps -Rubella

Courtney Hallum, MD, LPCH Blue Team and PEC Rotations, February 2009

Presentation Common Uncommon Rare

Chronic Unilateral -Nontuberculous mycobacterium -Cat-scratch disease

-Tuberculosis-Toxoplasmosis-Actinomycosis

-Nocardia brasiliensis -Aspergillosis

Chronic Bilateral -Epstein-Barr virus-Cytomegalovirus

-HIV-Tuberculosis -Toxoplasmosis-Syphilis

Brucellosis-Histoplasmosis

Courtney Hallum, MD, LPCH Blue Team and PEC Rotations, February 2009

Clinical Assessment -The physician will be aided in the pursuit of an explanation for the lymph-adenopathy by

a careful medical history,physical examination,selected laboratory tests, andan excisional lymph node biopsy.

Medical History :-It should reveal the setting in which lymphadenopathy is occurring.Symptoms such as sore throat, cough, fever, night sweats, fatigue, weight loss, or pain in the nodes should be sought.The patient's age, sex, occupation, exposure to pets, sexual behavior, and use of drugs such as diphenylhydantoin are other important historic points.

Medical History –

For example, children and young adults usually have benign (i.e., nonmalignant) disorders that account for the observed lymphadenopathy such as viral or bacterial upper respiratory infections; infectious mononucleosis; toxoplasmosis; and, in some countries, tuberculosis.

In contrast, after age 50, the incidence of malignant disorders increases and that of benign disorders decreases.

Physical examination :-

It can provide useful clues such asthe extent of lymphadenopathy (localized or generalized),size of nodes,texture,presence or absence of nodal tenderness,signs of inflammation over the node,skin lesions, andsplenomegaly.

Size of the lymph node(s)

Nodes <1.0 cm2 in area (1.0 cm x 1.0 cm or less) are almost always secondary to benign, nonspecific reactive causes.

In one retrospective analysis of younger patients (9–25 years) who had a lymph node biopsy, a maximum diameter of >2 cm served as one discriminant for predicting that the biopsy would reveal malignant or granulomatous disease.

Patients with node(s) 1.0 cm2 should be observed after excluding infectious mononucleosis and/or toxoplasmosis unless there are symptoms and signs of an underlying systemic illness.

The texture of lymph nodes may be described as soft, firm, rubbery, hard, discrete, matted.

It may be tender or non-tender.

It may be movable or fixed.

Tenderness is found when the capsule is stretched during rapid enlargement, usually secondary to an inflammatory process.

Some malignant diseases such as acute leukemia may produce rapid enlargement and pain in the nodes.

E.g. Nodes involved by lymphoma tend to be large, discrete, symmetric, rubbery, firm, mobile, and non tender.

Texture of lymph nodes

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Clinical Assessment -Nodes containing metastatic cancer are often hard, nontender, and nonmovable because of fixation to surrounding tissues.

The co-existence of splenomegaly in the patient with lymphadenopathy implies a systemic illness such as

infectious mononucleosis,lymphoma,acute or chronic leukemia,SLE,sarcoidosis,toxoplasmosis,cat-scratch disease, orother less common hematologic disorders.

Clinical Assessment -PALPATION OF LYMPH NODES –

Lymph node and chain palpation starts with the parotid and preauricular area which may also be palpated bimanually.

Palpating with light finger pressure against underlying firm tissues (bone or muscle), or bimanually where appropriate.

The head and neck lymph examination continues down the mandible to the submandibular region where bilateral palpation proceeds forward to the submental nodes just under the chin.

Clinical Assessment -

With the patient seated upright, head tipped slightly forward, the cervical lymphatic chains are palpated against the sternocleidomastoid muscle.

Superficial cervicals lymph nodes are found along the anterior border, and deep superior and inferior chains found along the posterior border.

Laboratory Investigation -

The laboratory investigation of patients with lymphadenopathy must be tailored to elucidate the etiology suspected from the patient's history and physical findings.

Complete Blood Count, CBC provide useful data for the diagnosis of

acute or chronic leukemias,EBV or CMV mononucleosis,lymphoma with a leukemic component,pyogenic infections, orimmune cytopenias in illnesses such as SLE.


Serologic studies – may demonstrate antibodies specific to components of EBV, CMV, HIV, and other viruses;Toxoplasma gondii;Brucella; antinuclear and anti-DNA antibody in case of SLE.

Chest x-ray –usually negativethe presence of a pulmonary infiltrate or mediastinal lymphadenopathy would suggest tuberculosis, histoplasmosis, sarcoidosis, lymphoma, primary lung cancer, or metastatic cancer


Lymph node biopsy –The indications for biopsy are imprecise, yet it is a valuable diagnostic tool.The decision to biopsy may be made early in a patient's evaluation or delayed for up to two weeks. Prompt biopsy should occur if the patient's history and physical findings suggest a malignancy;

E.g. a solitary, hard, nontender cervical node in an older patient who is a chronic user of tobacco;supraclavicular adenopathy; andsolitary or generalized adenopathy that is firm, movable, and suggestive of lymphoma.


Fine-needle aspiration –It should not be performed as the first diagnostic procedure.Fine-needle aspiration should be reserved for thyroid nodules and for confirmation of relapse in patients whose primary diagnosis is known.

Ultrasonography :–Normal cervical nodes appear sonographically as somewhat flattened hypoechoic structures with varying amounts of hilar fat.

US appearance of normal lymph node. Image shows flattened hypoechoic cigar-shaped structure (arrow).

Used to determine the long (L) axis, short (S) axis, and a ratio of long to short axis in cervical nodes.

An L/S ratio of <2.0 has a sensitivity and a specificity of 95% for distinguishing benign and malignant nodes in patients with head and neck cancer.

J Nucl Med 2004; 45:1509–1518Dentomaxillofacial Radiology (2000) 29, 133 - 143

Ultrasonography :–

Malignant infiltration alters the US features of the lymph nodes, resulting in enlarged nodes that are usually rounded and show peripheral or mixed vascularity.

Using these features, US has been shown to have an accuracy of 89%– 94% in differentiating malignant from benign cervical lymph nodes

J Nucl Med 2004; 45:1509–1518Dentomaxillofacial Radiology (2000) 29, 133 - 143

US image of a deep cervical (level four) lymph node in a patient with a nasopharyngeal SCC. The nodal hilum is hyperechoic relative to the hypoechoic peripheral cortex. The increased size (14 mm) and the eccentric cortical widening are indicators ofmalignant involvement

J Nucl Med 2004; 45:1509–1518

Imaging of malignant cervical lymph-adenopathy :-

Identifcation of cervical lymphadenopathy is critical to the management and outcome of diseases that present with malignant nodal infiltration.

Squamous cell carcinoma(SCC) of the head and neck is the commonest tumour of the upper aerodigestive tract and the presence of cervical lymph node metastases in these patients is of particular prognostic and therapeutic significance, with a single lymph node metastasis reducing survival by one-half.

Dentomaxillofacial Radiology (2000) 29, 133 - 143

General Principles :-

The imaging criteria used to determine metastatic cervical lymphadenopathy include –

nodal necrosis an heterogeneous appearance on CT or MRI andeccentric cortical widening on US.

Recent imaging advances have concentrated on potential differences in the `function' of malignant lymph nodes as demonstrated by

differential uptake of radio-labelled fluorodeoxyglucose (FDG) positron emission tomography (PET) ortissue specific MRI contrast media.


Computed Tomography :-

CT remains the most widely used modality for neck imaging.

The CT examination is performed in the axial plane with contiguous sections of 3 ± 5 mm whilst a bolus of intravenous contrast media is administered.

CT criteria for assessing lymph node metastases are based on size, shape, the presence of central necrosis and the appearance of a cluster of nodes in the expected lymph drainage pathway for the tumour.


Computed Tomography :-The most effective size criteria for indicating metastatic involve-ment are now defined as minimum axial diameters in excess of 11 mm in the jugulodigastric region and in excess of 10 mm elsewhere.

Using these sizes a sensitivity of 42% and specificity of 99% per node were produced.

With the use of spiral CT, it is possible to reconstruct the image in any plane with good quality, allowing more accurate calculation of the maximal axial and longitudinal dimensions and thus assessment of nodal shape.


Computed Tomography :-Nodal grouping in the drainage chain of a tumour is a further indicator of metastatic disease . This is defined as three or more contiguous or confluent lymph nodes, each of which has a minimal axial diameter of 8 ± 10 mm.


Axial CT scan with intravenous contrast demonstrating bilateral deep cervical (level two) lymph nodes.


The most accurate CT predictor of metastasis is the presence of central necrosis, which has been said to have a 100% specificity.

This is seen as a central area of low attenuation surrounded by a thick, irregular rim of enhancement and is due to nodal replacement of the medulla by less enhancing tumour.


Axial CT scan with intravenous contrast demonstrating a left-sided tongue SCC extending across the midline. There are bilateral enlarged submandibular (level one) lymph nodes demon-strating marked necrosis.


Nodal necrosis may be mimicked by lipid metaplasia which represents fatty degeneration secondary to inflammation or irradiation.

However, this fatty change generally occurs at the periphery of the node. Abscess formation may also have a similar appearance but such suppurative transformation is usually evident clinically.


Axial CT scan with intravenous contrast demonstrating lipid metaplasia (arrow) eccentrically placed in a left submandibular (level one) lymph node which has a 6mm minimum axial diameter.

Magnetic resonance imaging :-

Standard protocols for MRI of the cervical lymph nodes include a selection of T1- and fast spin echo T2- weighted axial, coronal and sagittal images.

STIR sequences allow a combination of T1- and T2-weighting with fat suppression, and malignant nodes are clearly demon-strated as high signal.

T1-weighted images depict lymph nodes as being of intermediate signal intensity, similar to muscle, whilst T2-weighted images show them as hyperintense signal.


Magnetic resonance imaging :-

(a) T1 weighted and (b) T2 weighted sagittal MRI scans demonstrate a large pathological deep cervical lymph node (level two/ three) which is of intermediate signal on T1 and high signal on T2

a b


Positron emission tomography :-

Most head and neck PET imaging is performed with the radiolabelled glucose analogue FDG which has increased uptake in viable malignant tumour due to enhanced glycolysis.

The result can be expressed as a standardised uptake value (SUV), with those values greater than two being considered abnormal.

PET scanning provides functional rather than anatomical imaging.

Dentomaxillofacial Radiology (2000) 29, 133 – 143

Positron emission tomography :-

A 57-y-old woman with chest pain after lobectomy for lung cancer 4 mo earlier. (A) Axial CT scan shows mixed soft tissue and fluid in left pleural space. Prevascular and axillary lymph nodes were interpreted as normal. (B) Axial dual PET/CT scan shows increased uptake in soft-tissue mass as well as small prevascular and axillary lymph nodes, indicating recurrent disease with metastatic nodal spread.

J Nucl Med 2004; 45:1509–1518

Advanced Imaging Techniques :-

Planar lympho-scintigraphyHybrid SPECT/CT imagingDynamic contrast – enhanced MR imagingUltra-small super-paramagnetic iron oxide (USPIO) enhanced MRI Gadolinium enhanced MRI

Differential Diagnosis of Cervical Lymph-adenopathy :-

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Conclusion :-

In conclusion, the lymphatic system and its organs are widespread and scattered throughout the body. It functions to service almost every region of the body. Because the vessels of the lymphatic system span the entire body it becomes an easy portal for the spread of cancer and other diseases, which is why disorders and diseases of this system can be so devastating.

References :-Textbook of Head and Neck Anatomy (Hiatt – Gartner) 4th Ed. 2010Grant's Atlas of Anatomy,13th Ed.Gray's Anatomy – 40th Ed.Anatomy of the Human Body - Henry GraySaladin: Anatomy & Physiology: The Unity of Form and Function, 3rd EditionEmbryology Atlas , John F NeasLife Map – Embryonic development & stem cell compendiumButler M G, Isogai S, Weinstein B M. Lymphatic development, Birth Defects Res C Embryo Today. 2009 September ; 87(3): 222–231.Albrecht I, Christofori G, Molecular mechanisms of lymphangiogenesis in development and cancer; Int. J. Dev. Biol. 55: 483-494Ferrer R, Lymphadenopathy: Differential Diagnosis and Evaluation; Am Fam Physician. 1998 Oct 15;58(6):1313-1320Som P M, Hugh D C, Mancuso A A, An imaging-based classification for the cervical nodes designed as an adjunct to recent clinically based nodal classification;Arch Otolaryngol Head Neck Surg. 1999;125:388-396.

References :-

Oliver G, Detmar M, The rediscovery of the lymphatic system: old and new insights intothe development and biological function of the lymphatic vasculature; Genes Dev. 2002,16: 773-783Sambandan T, Mabel C R, Cervical lymphadenopathy- a review; JIADS,2011,2,1:31-33.Torabi M, Aquino S L, Harisinghani M G, Current concept in lymph node imaging; J Nucl Med, 2004; 45:1509-1518.Connor SEJ, Olliff JFC, Imaging of malignant cervical lymphadenopathy – a review; Dentomaxillofacial Radiology, 2000;29:133-143.

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lymphatic drainage of head & neck

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