A lymph node or lymph gland, as it is also called, is a vital part of the immune system. There are three transportation networks well distributed around the body: the blood, the nervous system, and the lymphatic system.
The lymphatic system is a system of vessels like arteries and veins in which lymphatic fluid travels. Parts of the lymphatic network include the spleen, tonsils, lymph glands or nodes, and adenoids.
The lymph nodes stand on the first role of defense for the immune system, protecting the body from microorganisms such as bacteria, viruses, and fungi that could infect the body and cause an illness.
These nodes are clusters of immune cells and are found in strategic locations in the body, and they stand by as a defense mechanism.
Structure of Lymph Node
Externally, the lymph nodes look like small, coffee-bean-shaped glands located throughout the entire lymphatic system. The size of a lymph node ranges from 0.1 to 2.5 cm long.
They are surrounded by a fibrous capsule just like the spleen, and the fibrous capsule extends inside a lymph node to form trabeculae. Structurally, a lymph node is divided into the outer cortex, followed by a paracortex and an inner medulla (a feature like a kidney).
Hundreds of lymph nodes are well distributed like checkpoints around the body but are clustered in a certain vital region. On the lymph nodes’ concave surface is an indented surface known as the hilum, where lymphatic vessels leave, and blood vessels enter and exit the node.
On the convex surface of a node, lymph (lymphatic fluid) enters through multiple afferent lymphatic vessels and flows into various sinuses.
The lymph drains into a space below the capsule called the subcapsular sinus from the afferent lymphatic vessels, then into the cortical sinuses.
All these sinuses collectively empty into the efferent lymph vessels to leave the node at the concave side (through the hilum). Internally, the structure of the nodes is quite complex.
B cells (B lymphocytes) are found in the cortex, with T cells (T lymphocytes) and dendritic cells in the paracortex. In the medulla, plasma cells and macrophages are found here.
A fibrous capsule confines an entire lymph node. A lymph node contains lymphoid tissue, a meshwork of fibers called reticulum with white blood cells (WBCs) entangled in it.
The areas, where there are few cells within the meshwork, are referred to as lymph sinus. Reticular cells, fixed macrophages, and fibroblasts usually line up the lymph sinus.
Cells of Lymph Nodes
As earlier mentioned, a lymph node is a secondary lymphoid organ of the lymphatic system. The lymph nodes cells are called Lymphocytes; these are white blood cells and are majorly made up of T cells and B cells.
T cells and dendritic cells are primarily found in the paracortex. In contrast, B cells are primarily found in the cortex, cluster together as follicular B cells in lymphoid follicles. Fewer cells are found in the medulla when compared to the cortex. Platelets and macrophages are in the medulla.
A reticular network in the nodes provides structural support and a surface for the lymphocytes’ adhesion, dendritic cells, and macrophages.
As a part of this reticular network, there are also follicular dendritic cells in the B cells follicle and fibroblastic reticular cells in the T cells cortex.
The reticular network allows for the exchange of material with blood through the high endothelial venules and provides regulatory factors necessary for maturation and immune cell activation.
Functions of Lymph Node
Lymph nodes function as filters, or in equivalence, security guards to filter viruses, bacteria, pathogens, and other foreign microbes (even cancerous cells) brought to the nodes via lymphatic vessels.
This function is the primary reason why the numbers of lymph nodes are increased in people with cancer and other chronic infections.
A lymph node is the first junction where cancer cells are caught on their way to explore and set up home elsewhere in the body. In combating infections, lymph nodes play a vital role. Not only do they trap bacteria and viruses so that activated T cells can attack.
But a strain of T cells presents the foreign body (or an antigen of the foreign body) to B cells to make antibodies against the foreign body. In this sense, a lymph node is a place where communication and interaction of immune cells occur.
Types and Locations of Vital Lymph Nodes
In the body, there are approximately 600 lymph nodes distributed in the entire body. Clusters of nodes are found in the neck, chest, arms, abdomen, and groins.
Lymph nodes are casually referred to as swollen glands. This reference is because some persons may note painless swellings in their necks when the body is fighting a cold or sore throat, but these nodes are in many regions of the body.
Lymph nodes are more easily felt in ectomorphic individuals, and sometimes locating nodes that are seldom felt in general can be alarming. Some important lymph nodes include:
Lymph nodes of the Head
The lymph nodes found in the Head include occipital lymph nodes, mastoid lymph nodes, and parotid lymph nodes.
Lymph nodes of the Neck (Cervical Lymph nodes)
These nodes are likely felt in the neck of a patient fighting an upper respiratory tract infection. Cervical nodes filter lymphatic fluid coming from the Head, scalp, and neck.
These groups of nodes are subdivided into three primary regions, which region is involved provides essential information for doctors when diagnosing an illness:
- Anterior cervical lymph nodes: Lymph nodes nearest to the front of the neck. Patients with sore throat or common cold are very likely to feel these sets of cervical nodes.
- Posterior cervical lymph nodes: These lay behind the band of muscles that run on the neck’s lateral side (sternocleidomastoid). These nodes become enlarged when people contract infectious mononucleosis.
- Occipital lymph nodes: These nodes are located on the back of the neck at the skull’s base and swollen in patients with infectious mononucleosis.
Axillary Lymph Nodes
These are lymph nodes located in the armpits. There are usually about 10 to 40 lymph nodes in the axilla, most of which are removed when they have an axillary lymph node dissection for breast cancer.
Axillary nodes are used to describe an essential finding with cancer. When cancerous cells travel through the lymph, they are first to pick up by lymph nodes, and these lymph nodes have been discovered to be affected in order.
Supraclavicular Lymph Nodes
These are lymph nodes whenenlarged, can be felt just above the clavicle (collarbone). Most times, enlargement of these nodes signifies a severe underlying cause such as lymphomas or lung cancer.
Mediastinal Lymph Nodes
Lymph nodes in the mediastinum (area in the center of the chest between the lungs) are mediastinal lymph nodes. Typically, people can’t feel these nodes, but visualization can be made by imaging studies such as a CT scan and PET scan.
In staging lung cancer and some types of lymphomas, determining whether cancer cells are present in these nodes is essential. The mediastinal nodes are in tight connections with the abdominal nodes along the esophagus and the stomach.
This connection facilitates the spreading of cancer cells through these lymphatics in abdominal cancer cases and particularly esophageal cancer.
Inguinal Lymph Nodes
Inguinal lymph nodes are those in the groin region. They actively drain tissues from the feet to the groin, and since they drain such a large area, there are so many reasons why these nodes can be become swollen.
After an injury or infection to the lower limbs, they become swollen, and their inflammation may also be a sign of anything from a sexually transmitted disease to cancer.
It is important to note that most individuals experience swollen lymph nodes in the groin, and most of the time, the swellings are no problem. They perform their traditional duty of trapping viruses or bacteria that enter the body from sore on the feet or legs.
Retroperitoneal Lymph Nodes
Retroperitoneal Nodes are located deep in the abdomen and can only be seen during imaging studies. They are the nodes that are first affected by testicular cancer.
Mesenteric Lymph Nodes
These nodes are closely associated with the retroperitoneal nodes, lying deep in the abdomen, in the surrounding intestine’s membranes. In young adults, these nodes may become swollen with symptoms that can sometimes mimic appendicitis.
Pelvic Lymph Nodes
Pelvic lymph nodes also lie deep in the body (pelvis) and can only be seen on an imaging scan. They are involved with cancer, particularly prostate and bladder cancer.
List of All Lymph Nodes in the Body
|LOCATION||TYPES and SUBDIVISIONS|
|HEAD||• Occipital lymph nodes|
• Mastoid lymph nodes
• Parotid lymph nodes
|NECK||• Cervical lymph nodes|
– Submental lymph nodes
– Submandibular lymph nodes
• Deep cervical lymph nodes
– Deep anterior cervical lymph nodes
– Deep lateral cervical lymph nodes
• Inferior deep cervical lymph nodes
– Jugilo-omohyoid lymph nodes
– Jugulodigastric lymph node
• Supraclavicular lymph nodes
– Virchow’s node
|THORAX||• Lymph nodes of the Lungs|
– Subsegmental lymph nodes
– Segmental lymph nodes
– Interlobar lymph nodes
• Mediastinal Lymph nodes
|ABDOMEN||• Periaortic lymph nodes|
– Preaortic lymph nodes
– Celiac lymph nodesHepatic lymph nodes
– Gastric lymph nodes
– Splenic lymph nodes
– Superior mesenteric lymph nodes
– Inferior mesenteric lymph nodes
Retroaortic lymph nodes
|ILIAC||• Common iliac lymph nodes|
• Internal iliac lymph nodes
• External iliac lymph nodes
|PELVIS||• Sacral lymph nodes|
• Retroperitoneal lymph nodes
|ARMS||• Superficial lymph nodes|
– Supratroclear nodes
– Deltoideopectoral nodes
• Deep lymph nodes of the arms
– Lateral nodes
– Pectoral or anterior nodes
– Subscapular or Posterior nodes
– Intermediate or Central nodes
– Subclavicular or Medial nodes
|LOWER LIMBS||• Superficial inguinal lymph nodes|
• Deep inguinal lymph nodes
• Popliteal lymph nodes
Complications of the Lymph node
There are conditions where lymph nodes can be affected. The medical term for these conditions is lymphadenopathy, describing a swelling or an inflammation in these glands.
Some conditions that can result in lymphadenopathy include:
Since white blood cells are stored in lymph nodes, and these white blood cells serve as the first line of defense against infections, the infections can often cause lymph nodes’ enlargement.
This situation can either present a positive or a negative meaning. Positively, a growth can signify that the lymph nodes are functioning correctly.
Though not understood, however, it has been thought that removing the tonsils would help prevent infections. When tonsils are seriously damaged, removing them might not be a bad idea, but it can lead to grave consequences if they are healthy.
Lymph nodes can trap viruses or bacteria that they are easily susceptible to. When this happens, a generalized lymph node infection may arise from an infected wound. Infective conditions involving lymph nodes often cause a significant fever and chills.
Some cancer trends are closely associated with lymph nodes, but their roles often differ between solid tumors and lymphomas. With solid tumors like breast cancer, the cancerous cells travel to lymph nodes before traveling (metastasizing) to other areas of the body.
Cancer conditions that have spread to lymph nodes are usually higher than those that have not, indicating a greater risk of spreading. On the contrary, in lymphomas, cancer begins in the lymph nodes.
When it affects other regions other than lymph nodes, it is not referred to as metastasis as solid tumors but rather as extranodal involvement.
Many other disorders can result in swelling of lymph nodes, ranging from autoimmune diseases such as rheumatoid arthritis to genetic syndromes.
Evaluation of Lymph nodes
When evaluating a lymph node, health care professionals may use any of the following terms:
- Painful or Non-painful: Generally, infections can cause tender lymph nodes (painful), and cancerous nodes are often not tender (non-painful). However, exceptions may exist.
- Mobile or Fixed: Fixed lymph nodes appear to be attached to a structure deeper in the body, whereas mobile nodes can easily be moved around when palpated. Generally, mobile nodes are benign, while fixed nodes suggest the possibility of cancer.
- Localized or Generalized: The term localized is employed to suggest a lymph node in only one location. When generalized lymphadenopathy is present, it is more likely to be infectious such as mononucleosis.
- Matted: Few times, lymph nodes appear to be attached in a clump, and the term used to describe this is matted.
- Lymph node; https://en.m.wikipedia.org/wiki/Lymph_node
- Swollen Lymph Nodes; https://www.webmd.com/a-to-z-guides/swollen-glands
- How to check your Lymph Nodes; https://www.plymouthhospitals.nhs.uk/how-to-check-your-lymph-nodes
- Lymph Nodes; https://training.seer.cancer.gov/anatomy/lymphatic/components/nodes.html