Lymph Nodes Definition: Lymph nodes: Lymph nodes are small encapsulated organs located along the pathway of lymphatic vessels. They vary from about 1 mm to 1 to 2 cm in diameter and are widely distributed throughout the body, with large concentrations occurring in the areas of convergence of lymph vessels. They serve as filters through which lymph percolates on its way to the blood. Antigen-activated lymphocytes differentiate and proliferate by cloning in the lymph nodes. They are packed tightly with the white blood cells called lymphocytes and macrophages.
Functions: The lymph nodes filter and monitor the lymph, an interstitial fluid, for foreign particles. These foreign particles commonly known as pathogens, or germs, can set up infections anywhere in the body. The lymph fluid inside of the lymph nodes contains lymphocytes, a type of white blood cell, which are continuously recirculated through the lymph nodes and the bloodstream. A germ, such as bacteria, will produce a chemical substance called an antigen which circulates through the bloodstream, the lymph system, and into lymph nodes.
In response to the antigens, the lymphocytes in the lymph node make an antibody which will go out of the lymph node into circulation, seek, and destroy the infection producing the antigen. Other immune system cells will be made to fight the infection and “sent” to the lymph nodes. The increased numbers of immune system cells fighting the infection will make the node expand and become “swollen. ” Structure: Germinal Center- source of lymphocytes Afferent lymph veins Efferent lymph veins Medullary region – source of macrophages Types: 1. Cervical Lymph Nodes
Cervical lymph nodes are lymph nodes found in the neck. The medical term for the neck is cervix, though this term is rarely used. There are approximately 300 lymph nodes in the neck, and they can be classified in many different ways. Deep Lymph Nodes 1. Submental 2. Submandibular (Submaxillary) Anterior Cervical Lymph Nodes (Deep) 3. Prelaryngeal 4. Thyroid 5. Pretracheal 6. Paratracheal Deep Cervical Lymph Nodes 7. Lateral jugular 8. Anterior jugular 9. Jugulodigastric Inferior Deep Cervical Lymph Nodes 10. Juguloomohyoid 11. Supraclavicular (scalene) . Axillary Nodes The Axillary lymph nodes are of large size, vary from twenty to thirty in number, and may be arranged in the following groups: * brachial lymph nodes (or “lateral”) * pectoral axillary lymph nodes (or “anterior”) * subscapular axillary lymph nodes (or “posterior”) * central lymph nodes * apical lymph nodes (or “medial” or “subclavicular”) Axillary lymph nodes are simply lymph nodes located in the armpits. The medical term for armpits is axilla. These drain the whole of the arm, and are divided into two groups, superficial and deep.
The superficial nodes are supplied by lymphatics that are present throughout the arm, but are particularly rich on the palm and flexor aspects of the digits. 3. Inguinal Nodes Inguinal lymph node is a type of lymph node in the inguinal region. It can refer to: * Superficial inguinal lymph nodes The superficial inguinal lymph nodes form a chain immediately below the inguinal ligament. They lie deep to Camper’s fascia which overlies the femoral vessels at medial aspect of the thigh. They are found in the triangle bounded by the inguinal ligament superiorly, the border of the sartorius musclelaterally, and the adductor longus muscle medially. Femoral Triangle of Scarpa). There are approximately 10 superficial lymph nodes. The superficial nodes drain to the deep inguinal lymph nodes. * Deep inguinal lymph nodes The deep inguinal lymph nodes are located medial to the femoral vein and under the cribriform fascia. There are approximately 3 to 5 deep nodes. The superior-most node is located under the inguinal ligament and is called Cloquet’s node. 4. GI Nodes Lymph nodes from the esophagus to the abdomen. Cervical Nodes Axillary Nodes GI Nodes Inguinal Nodes