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Lymph Nodes

Any of us with lymphedema are well aware of the term “lymph nodes. We all understand that mass removal of lymph nodes for cancer biopsy is the leading cause of secondary lymphedema and that missing or malformed lymph nodes (in addition to lymphatic distortions) is one of the reasons for primary lymphedema.

Lymph nodes are small bean shaped structures lying along the course of lymphatics. They are aggregated in particular sites such as the neck, axillae, groins and para-aortic region. Knowledge of the sites of lymph nodes is important in physical examination of patients.

They have two main functions.

First, they function as the body’s “sewer” system collecting waste fluids and carrying them out to where they can be eliminated.

Secondly, they are incredibly important to our body’s disease fighting system. I hope this page will give greater clarity to what lymph nodes are, what they specifically do and how they function.

Pat

Feb. 5, 2012

Basic groups of lymph nodes

Cervical - Nodes in the neck

Axillary – Nodes in the armpits

Supraclavicular - Nodes along the collar bone

Mediastinal – Nodes in the upper body behind the sternum and between the pleural sacs (lung sacs)

Mesentery - Nodes in the lower body (abdomen) below the rib cage

Inguinal – Nodes in the groin

Femoral – Nodes in the upper inner thigh

Functions of Lymph Nodes

Defense functions

Filtration and phagocytosis.

The structure of the sinus channels within the lymph nodes slows the lymph flow through them.

This gives the reticuloendothelial cells that line the channels time to remove microorganisms and other injurious particles (soot) from the lymph and phagocytose them.

Sometimes such large numbers of microorganisms enter the node that the phagocytes cannot destroy enough of them to prevent their injuring the node.

An infection of the node, adenitis, then results.

Because cancer cells often break away from a malignant tumor and enter the lymphatics, they travel to the node, where they may set up new growths.

Hematopoiesis

The lymphatic tissue of lymph nodes serve as the sites of the final stages of maturation for some types of lymphocytes and monocytes that have migrated from the bone marrow.(1)

Lymph node distribution

Lymph nodes are organized in groups that drain specific regions of the body. This knowledge guides the clinician to inspect particular areas of anatomy when lymphadenopathy occurs.

Lymphatic drainage of the head and neck is traditionally divided into 6 regions. The most important nodes in this grouping are around the internal jugular lymph nodes. The superior aspect is termed region II; it receives lymph from the supraglottic larynx, anterior nasopharynx, and c via submental and submandibular lymph nodes (region I). The middle portion of the internal jugular chain is region III; it collects drainage from the superior hypopharynx and superior larynx via direct drainage through lymphatic capillaries.

The inferior part of the internal jugular chain is region IV; it collects drainage from the inferior hypopharynx, inferior larynx, and thyroid and supraclavicular regions. Region VI sits in the anterior aspect of the neck; it contains supraclavicular, pretracheal, and thyroid nodes, which drain into region IV. Region IV of the internal jugular chain is the common collecting point for regions I-III and VI. Region V collects lymph from the scalp and posterior nasopharynx. All lymphatic drainage from region V and region IV on the internal jugular chain collect into the jugular trunk (ie, a group of nodes positioned at the internal jugular anterior brachiocephalic veins) and then subsequently into the thoracic duct on the left or directly into the brachiocephalic vein on the right.

The thoracic cavity maintains a distinct collection of lymph nodes, with a slightly complex drainage route that parallels bronchi, arteries, and veins. Each major bronchi division has a collection of nodes called the intrapulmonary lymph nodes, which lie within the lungs and drain each of the lung's corresponding segments. The intrapulmonary nodes drain into a set of nodes, the left and right bronchopulmonary (hilar) lymph nodes, which are located at the junction of each lung and its main bronchi. These nodes collect the lymphatic drainage from the segments of their respective lung.

At the bifurcation of the trachea and beginning of each bronchus, 3 sets of nodes reside, the right and left tracheobronchial lymph nodes and the inferior tracheobronchial lymph nodes. An unusual feature of this anatomy is that the inferior tracheobronchial nodes, also known as the carinal nodes, collect lymph from the left lower lobe but drain that fluid into the right tracheobronchial lymph nodes. This is significant because a suspicious-appearing lymph node in the right hilar region should prompt evaluation of the left lower lobe and the right lung.

Aligned with the sides of the trachea are groups of nodes known as the right and left paratracheal lymph nodes, which collect lymphatic fluid from the right and left tracheobronchial nodes, respectively. The posterior thoracic cavity is drained via the intercostal lymph nodes and into the posterior mediastinal lymph nodes. The anterior thoracic cavity is drained through the parasternal lymph nodes, which are located next to the sternum in the intercostal space. The parasternal lymph nodes collect lymph from the anterior mediastinum and communicate with the medial aspect of the anterior chest wall. The common drainage site for all of the aforementioned lymph nodes is into the jugular trunk and then into the thoracic duct on the left or directly into the brachiocephalic vein on the right.

The thoracic duct is the final common lymphatic drainage system for the lower extremities, pelvis, mesentery, most of the thoracic cavity, left upper extremity, and left head and neck. The thoracic duct is positioned on the right side of the aorta in the abdomen and receives lymph from the cisterna chyli. It ascends up through the thorax in the posterior mediastinum while receiving lymphatic drainage from the intercostal nodes. It crosses over to the left just below the carina and ascends to the level of the junction of the left internal jugular and left subclavian vein, where it connects into the venous system. The upper intercostal nodes and right apical axillary nodes drain directly into the right brachiocephalic vein via the right bronchomediastinal trunk, and lymphatic drainage from the right side of the head and neck drain directly into the right brachiocephalic vein via the right jugular trunk.

The upper extremity lymph node distribution consists of the cubital fossae and axillary region. The axillary group is subdivided into 5 subgroups. The lateral axillary group drains the upper extremity and receives lymph from the posterior axillary group, which in turn drains the posterior chest wall. The anterior axillary nodes drain lymph from the anterior chest wall. The lateral and anterior groups drain into the central axillary group, which in turn drains into the apical axillary (or subclavian) group. The apical axillary nodes drain into the thoracic duct on the left or directly into the brachiocephalic vein on the right.

The intra-abdominal lymphatic drainage parallels the arterial system. Lymph nodes lie in the mesentery, adjacent to an arterial counterpart. Each artery has a cluster of nodes that receives lymph from its corresponding arterial supply: celiac, superior, inferior mesenteric lymph nodes. These nodal groups eventually drain into the cisterna chyli, the beginning of the thoracic duct. The additional role of the mesenteric lymphatic system is to absorb and transport long-chain fatty acids via chylomicrons. Intestinal mucosal immunity is primarily the responsibility of Peyer patches, which are unencapsulated collections of lymphatic tissue in lamina propria located on the antimesenteric side of the ileum.

The 2 groups that serve the lower extremities are the popliteal nodes and the inguinal nodes. The inguinal nodes are grouped into external and internal subtypes. The external group drains the lower extremity and lymph from the anterior abdominal wall and external genitalia. The internal inguinal nodes then drain into the external iliac nodes, which join the lymphatic drainage of the pelvis, via the internal iliac nodes, to come together in the common iliac nodes. The 2 groups of common iliac nodes drain into the left and right lumbar nodes, beginning just proximal to the bifurcation of the aorta and eventually draining into the cisterna chyli, via left and right lumbar trunks. The cisterna chyli is the beginning of the thoracic duct. The kidneys and adrenal glands drain into lymph nodes around the renal vessels and subsequently into the lumbar nodes.(2)

Lymph Nodes and B Cells

B cells: These enter the lymph node via HEVs and pass to the follicles. If activated by antigenic stimulation they proliferate and remain in the node. Unstimulated B cells, however, pass out rapidly from the node to return to the general circulation. Activated B cells within the lymphoid follicles are known as follicle centre cells. The pale staining central area of a secondary follicle is known as a germinal centre and this is surrounded by a mantle zone consisting of small, naive B cells and a few T cells.

The follicle centre cells within the germinal centres consist of cells with cleaved nuclei (centrocytes) and cells with larger more open nuclei and several nucleoli (centroblasts).

Stimulated mature B cells responding to antigen change into centrocytes and then centroblasts. The centroblasts leave the follicle and pass to the paracortex and medullary sinuses, where they become immunoblasts. The immunoblasts divide to give rise to plasma cells or memory B cells which are ready for their next encounter with specific antigen.(3)

The Lymph Node

The lymph node is a tiny bean-shaped gland, located in many different areas of the body. The main locations are the neck, under the arms, and in the groin. The body has over 300 filtering selected white blood cells and foreign elements. The lymph node is a component of the lymphatic system. The lymphatic system moves lymph node fluid, waste substance, and nutrients through out your body bloodstream and tissues.

Each lymph node is also an important part of your immune system. Your lymph node filters fluids, catching viruses, bacteria, and other unknown materials. Then your unique white blood cells destroy the unwanted materials.

A lymph node may be found alone or in a group through out your body. The main groups can be felt in the following areas:

In the neck Under the arms In the groin

There are between 500 and 600 lymph nodes that are distributed throughout the human body. Some of these lymph nodes are found in clusters in the underarms, groin, neck, chest and abdomen.

Location of the Lymph Nodes

To begin with, you need to know that there are a lot of lymph nodes that are located in your head and neck. These are called cervical lymph nodes. There are actually 6 different types of lymph nodes that are located in this part of your body:

v Anterior cervical lymph nodes are both superficial and deep. They lie directly above and beneath the muscles that help you to flex and rotate your head.

Posterior cervical lymph nodes extend in a line that is found at the back of your neck.

Tonsillar lymph nodes are located just below your jaw bone.

Sub-mandibular lymph nodes run along the bottom of your jaw on both sides of it

Sub-mental lymph nodes can be found right below your chin.

Supraclavicular lymph nodes are located in the hollow area that is located directly above your collar bone.

The second area in which you have lymph nodes is in your arm. There are numerous lymph nodes that are found in this area of your body. They are grouped into 2 categories, which include:

Superficial lymph nodes are present throughout your arm. However, the areas in which you will find the most of this type of lymph nodes is on the palm of your hands and in the areas that are used to flex your fingers. There are 2 types of lymph nodes found here. The first are supratrochlear lymph nodes, which are situated above your elbow. The second are deltoideopectoral lymph nodes that are located in the bottom of your arm.

Deep lymph nodes comprise about 20 to 30 individual glands in your arm. These can be grouped into lateral glands, anterior or pectoral glands, posterior or subscapular glands, central or intermediate glands and medial or subclavicular glands.

The third area in which your lymph nodes are located are in your lower limbs. These are known as the Inguinal lymph nodes. Herein there are 2 types of lymph nodes. The first are called the deep inguinal lymph nodes. There are between 3 and 5 of these are located in your femoral vein. The second type are called superficial inguinal lymph nodes. These 10 lymph nodes form a triangle right beneath your hips. They are deeply embedded there.

Each of these different lymph nodes serves its own individual purpose. All of the jobs that lymph nodes do, regardless of what the job may be, is of great importance for your body to remain in optimal health. For this reason, it serves us well to take the time to know where in our body these lymph nodes are located and what their jobs are.

LymphNodes.com

More About Lymph Nodes

Lymph nodes occur in groups located along the larger lymphatic vessels. Though distributed throughout the body, they do not contain the tissues of the central nervous system. The lymph nodes primary function is the production of lymphocytes. Lymphocytes help defend the body against microorganisms, and remove harmful foreign particles and debris from lymph before it is returned to the blood stream. There are six major areas:

1) The cervical region: these nodes are grouped along the lower border of the jaw, in front of and behind the ears, and deep in the neck along the larger blood vessels. They serve to drain the skin of the scalp, face, tissues of the nasal cavity, and the pharynx.

(2) The axillary region: these nodes in the underarm region receive lymph from vessels that drain the arm, the walls of the thorax, the breast, and the upper walls of the abdomen.

(3) The Inguinal region: these nodes receive lymph from the legs, the outer genitalia and the lower abdominal wall.

(4) The pelvic cavity: these nodes generally appear alongside blood vessel paths within the pelvic cavity and receive lymph from lymphatic vessels in the pelvic area.

(5) The Abdominal cavity: these nodes occur in chains alongside main branches of arteries in the intestine and the abdominal aorta.

(6) The Thoracic cavity: these nodes occur between the lungs and along the windpipe and bronchi. The nodes receive lymph from the internal wall of the thorax. Popliteal and inguinal nodes occur in the legs and groin, lumbar nodes occur in the pelvic region, axillary nodes occur in the armpits, and cervical nodes occur in the chest. Hodgkin's disease is an enlargement of the lymph nodes in the neck, which gradually spreads throughout the lymphatic system, including the spleen. Pressure on organs and nerve endings adjoining these enlarged nodes can result in a dysfunction of vital organs or in paralysis.

Anatomy of the Lymph Node

Lymph nodes are encapsulated bean-shaped structures (normally <1 cm in diameter) containing a reticular network packed with lymphocytes, macrophages, and dendritic cells. They are present at the junctions of lymphatic vessels. Serve as the first organized structures to encounter most antigens. The major function of the lymph nodes is to filter antigen from the lymph.

Three regions to the lymph node

Cortex

Outermost layer - contains mostly B lymphocytes, follicular dendritic cells and macrophages arranged in clusters called primary follicles). Following antigenic stimulation they primary follicles become secondary follicles consisting of concentric rings of densely packed lymphocytes and central lymphocytes, macrophages, and dendritic cells. The GCs (germinal centers) contain large proliferating B lymphocytes and plasma cells interspersed with macrophages and dendritic cells. The GC is a site of intense B-Cell activation and differentiation into plasma cells and memory cells.

Paracortex

Layer just beneath the cortex It is an area populated with T lymphocytes and also interdigitating dendritic cells. It is an important site for T cell activation by these APCs.

Medulla

Inner most layer, more sparsely populated Many of the cells are plasma cells so there is a fairly high concentration of immunoglobulin at this site.

Afferent lymphatic vessels pierce the capsule of a lymph node at various sites and empty into the subcapsular sinus. There is a single efferent lymphatic vessel leading from the lymph node. High antibody concentration in the lymph leaving via the efferent lymphatic vessel and 50X more lymphocyes than in the afferent lymphatic vessels. This is due to proliferation of lymphocytes within the lymph node and due to an influx of lymphocytes from the circulatory system.

There is an affferent artery which enters the lymph node. Lymphocytes can enter the node by passing between specialized capillary endothelial cells in the postcapillary venules. This process is called extravasation. Antigenic stimulation can enhance this process 10X.

Therefore, the concentration of lymphocytes in the lymph nodes can increase greatly following antigenic stimulation accounting for ”swelling of lymph nodes”.

BioWeb

Disorders of the Lymph Nodes

Related Lymphedema People Blogs

Abstracts and Studies

Real-time mapping of rat stomach lymph nodes by quantum dots.

Feb 2012

Li P, Sun P, Yang W, Zhang X.

Source

Department of General Surgery, Huashan Hospital, Fudan University , Shanghai , China.

Abstract

Abstract Objective. To develop a real-time imaging method to identify the rat stomach lymph node basin with quantum dots (Qdots).

Material and methods. Six Sprague-Dawley rats received injections of 0.05 ml Qdots (1 mg/ml) in the subserosal layer in the lesser curvature of the gastric antrum. Subsequently, draining lymphatic channels and lymph nodes were visualized with a near-infrared fluorescence imaging system. Histological examination was required to confirm the presence of lymph nodes. Additionally, rats received injections of Qdots and underwent 2 weeks of observation to confirm if there was any abnormality. The distribution of Qdots was measured by inductively coupled plasma-mass spectrometry.

Results After injection of the Qdots, the gastric sentinel lymph nodes were visualized 15 min later. The fluorescence then began to spread. The intensity of fluorescence increased in the perigastric area at 60 min, and declined at 360 min. Histological analysis of the fluorescent tissue confirmed the presence of nodal tissue. The results of a cadmium assay showed that Qdots were mainly distributed in the liver, spleen and kidney of the rats. No apparent toxicity could be seen during the 2 weeks of observation.

Conclusions. NIR fluorescence imaging of lymph nodes with Qdots is a novel and reliable real-time technique that can be used to assist with identification and resection of stomach lymph nodes. The optimal observation time of perigastric SLNs was 15 min after the injection, and the optimal observation time of perigastric lymph nodes beyond the SLNs was 60-120 min after the injection.

PubMed

Microvascular architecture of human epicolic and paracolic lymph nodes located in the vicinity of colon cancer: A SEM study of corrosion casts.

Jan 2012

Pitynski K, Litwin JA, Richter P, Miodonski AJ.

Source

Department of Gynecology and Obstetrics, Jagiellonian University Medical College, Krakow, Poland.

Abstract

The vascular systems of epicolic and paracolic lymph nodes located in the vicinity of colon tumors resected from three patients were investigated by corrosion casting and scanning electron microscopy. Large vessels entered the nodes either at one site, not always corresponding with the anatomical hilus, or at 2-4 sites located along their perimeters. In the cortical zone of most examined nodes, the location of lymphoid nodules was marked by rosette-like capillary arrays drained by peripheral arcuate venules. The paracortex and medulla showed a dense capillary network with areas of tortuous capillaries, sometimes forming glomerular arrays suggesting nonsprouting angiogenesis by capillary elongation. Venules were abundant, especially in the paracortex and medulla, but high endothelial venules showing characteristic imprints of bulging endothelial cells in the casts were very rarely observed. Focal angiogenesis, abundance of venules and scarcity of high endothelial venules could result from remodeling of blood vessels induced by the tumor.

PubMed

Impaired lymphatic contraction associated with immunosuppression.

Sept 2011

Liao S, Cheng G, Conner DA, Huang Y, Kucherlapati RS, Munn LL, Ruddle NH, Jain RK, Fukumura D, Padera TP.

Source

EL Steele Laboratory, Department of Radiation Oncology, Harvard Medical School and Massachusetts General Hospital, Boston, MA 02114, USA.

Abstract

To trigger an effective immune response, antigen and antigen-presenting cells travel to the lymph nodes via collecting lymphatic vessels. However, our understanding of the regulation of collecting lymphatic vessel function and lymph transport is limited. To dissect the molecular control of lymphatic function, we developed a unique mouse model that allows intravital imaging of autonomous lymphatic vessel contraction. Using this method, we demonstrated that endothelial nitric oxide synthase (eNOS) in lymphatic endothelial cells is required for robust lymphatic contractions under physiological conditions. By contrast, under inflammatory conditions, inducible NOS (iNOS)-expressing CD11b(+)Gr-1(+) cells attenuate lymphatic contraction. This inhibition of lymphatic contraction was associated with a reduction in the response to antigen in a model of immune-induced multiple sclerosis. These results suggest the suppression of lymphatic function by the CD11b(+)Gr-1(+) cells as a potential mechanism of self-protection from autoreactive responses during on-going inflammation. The central role for nitric oxide also suggests that other diseases such as cancer and infection may also mediate lymphatic contraction and thus immune response. Our unique method allows the study of lymphatic function and its molecular regulation during inflammation, lymphedema, and lymphatic metastasis.

PNAS

Understanding How Lymph Nodes Respond To Infection May Redefine How Immune System Functions

Science Daily — DURHAM, N.C. – Duke University Medical Center researchers may have solved the mystery of why lymph nodes swell when the body fights infection. Their findings may redefine how the immune system functions, they said.

Their research, published in the December 2003 issue of Nature Immunology, centered on the role of mast cells. Mast cells are immune cells that are typically found just under the skin and in the lining of the intestine and lungs and were previously associated primarily with the induction of allergic reactions. The Duke researchers report that allergic reactions are only a side effect of mast cells' much more important role as a regulator of the body's immune system.

“Mast cells serve as the command post for the immune system during infections,” said Soman Abraham, Ph.D., professor of pathology, associate professor of immunology and senior author of the paper. “White blood cells are sequestered within these nodes and, following proper activation, they can specifically target infectious agents and aid the host in clearing unwanted pathogens.”

Abraham said the discovery that mast cells can initiate the activation and swelling of nodes through release of specific signaling molecules points to the possible use of mast cell products for the development of vaccines designed to boost the potency of the immune response.

“Mast cells have been much maligned because of their contribution to many diseases including asthma, arthritis, Crohn's disease and multiple sclerosis,” said Abraham. “Our research shows that mast cells play an important role in immune surveillance and defense against infectious agents.”

The human immune system comprises two components that protect it against invading pathogens. The first line of defense is the innate immune system, a quick-acting response triggered immediately when a pathogen enters the body. The innate immune response responds the same regardless of the pathogen and attacks the pathogen for the first several days until the adaptive immune response can begin its attack. The adaptive immune system is tailored specifically to the pathogen it is attacking. Once the immune system identifies an invader, draining lymph nodes recruit infection-fighting T-cells within 24 hours. During the next week or so, the T-cells proliferate and induce B-cells to produce antibodies specific to the invader. The result is swollen lymph nodes, which are the first discernable sign that the adaptive immune system is in effect. Previous studies by Abraham showed that mast cells trigger the body's innate immune system by releasing a molecule called tumor necrosis factor (TNF) and recruiting infection-clearing cells called neutrophils. However, the role of mast cells in the adaptive immune system remained unknown.

To examine the role of mast cells in the adaptive immune system, the Duke researchers studied the lymph nodes of mast cell-deficient mice. When the scientists introduced bacteria into the animals, their lymph nodes did not swell. However, when the mice were injected with mast cells, their nodes did swell. Further, specific activation of mast cells in the skin induced a rapid increase in TNF in the lymph nodes and recruitment of T cells. “We are showing that the mast cells are critically involved in both the innate and adaptive immune systems,” said Abraham. “Both are triggered with the release of TNF by the mast cells. The innate immune system, through TNF and neutrophils, attack the pathogen first, but within hours, TNF has reached the lymph nodes, triggering the adaptive immune system. Infection fighting T-cells are recruited and a specific attack on the pathogen begins. Within days, the body is producing antibodies and fighting back.”

The involvement of mast cells in the adaptive response is a major shift in the understanding of the immune system and its function, said Salvatore Pizzo, M.D., Ph.D., chairman of the department of pathology and a member of the research team.

“When you pick up a textbook two years from now that shows how the immune system functions and the way a node responds to an infectious agent, you are going to see a whole new pathway,” said Pizzo. “Mast cells are much more than just bad actors making you feel sick when you are exposed to noxious agents. They are actually major players helping you deal with these noxious agents.”

“With a clearer understanding of the adaptive immune system and the role of mast cells, comes the opportunity for new therapeutics that could improve disease protection,” said Abraham.

“It's been known, particularly with allergy and asthma, that mast cells are involved in immune dysfunction,” he said. “But their real physiological role is triggering both the innate and adaptive immune systems. Future research needs to focus on this role. We need to continue to dissect the process and adapt some of it to improve immunity and disease protection.”

The National Institutes of Health and the Sandler Foundation for Asthma Research funded the research. Co-authors of the paper include James B. McLachlan; Justin P. Hart, Ph.D.; Christopher P. Shelburne, Ph.D.; Herman F. Staats, Ph.D.; and Michael D. Gunn, M.D., all of Duke University Medical Center.

Science Daily

External Links

Related Lymphedema People Articles

Listing of Lymph Node Groups

Images

afferent_lymphatic_vessels.jpg

courtesy of:medArt

Lymphedema People Resources

lymph_nodes.txt · Last modified: 2012/10/16 14:40 (external edit)