Go Human lymphatic system
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Lymphatic system

The lymphatic system is a part of the vascular system that, together with the venous bed, participates in the outflow of fluids from tissues (Fig. 1). The roots of the lymphatic system are lymphatic capillaries, into which metabolic products come from tissues, and under pathological conditions, foreign particles and microorganisms. The cells of a malignant tumor can spread through the lymphatic vessels. Lymphatic capillaries are thin-walled endothelial tubes that connect to the network; they are available everywhere except the brain and spinal cord , the parenchyma of the spleen , cartilage, sclera and lens of the eye, the placenta . The diameter of the lymphatic capillaries is several times the diameter of the blood capillaries. At the confluence of lymphatic capillaries lymphatic vessels are formed, which are characterized by the presence of valves that provide the flow of lymph in one direction. Constrictions are formed at the locations of the valves, in connection with which the vessels have a clearly shaped form. Lymphatic vessels form wide-leafy plexuses in the walls of organs. Several groups of the diverting lymphatic vessels leaving the regional lymph nodes located nearby leave the organ or part of the body. Flowing through the lymph node, the lymph is enriched with lymphocytes.

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Lymph nodes are involved in blood formation and defense reactions of the body. They are active biological filters, produce antibodies and regulate lymph flow. In the lymph nodes, lymph currents merge from individual organs of a given area. Lymphatic vessels leaving the lymph nodes form larger vessels - lymph trunks (lumbar, intestinal, subclavian, jugular, and broncho-mediastinal). The trunks merge into two lymphatic ducts: the thoracic duct, which collects lymph from the tissues of 3/4 of the body, and the right lymphatic duct, which collects the lymph from the right half of the head and neck, the right half of the chest cavity and the right hand. The thoracic duct (from 30 to 41 cm long) begins in the abdominal cavity, passes through the diaphragm into the posterior mediastinum and continues on the neck, falling into the left subclavian vein. The right lymphatic duct (1-1.5 cm long) is located on the border of the neck and chest to the right and flows into the right subclavian vein. The lymphoid follicles of the mucous membranes and tonsils are also referred to the lymphatic system.

Human lymphatic system
Fig. 1. Human lymphatic system (front view): 1 - lymphatic vessels of the face; 2 - submandibular lymph nodes; 3 - chin lymph nodes; 4 - the mouth of the thoracic duct; 5 - anterior mediastinal lymph nodes; 6 - axillary lymph nodes; 7 - superficial lymphatic vessels of the arm, following along the head vein; 8 - the medial group of the superficial lymphatic vessels of the hand; 9 - lumbar lymph nodes; 10 - superior ileal lymph nodes; 11 - internal iliac lymph nodes; 12 - superficial inguinal lymph nodes; 13 - the medial group of the superficial lymphatic vessels of the leg; 14 - the lateral group of the superficial lymphatic vessels of the leg; 15 - superficial lymphatic vessels of the foot; 16 - deep lymphatic vessels of the foot; 17 — deep lymphatic vessels of the lower leg; 18 - deep lymphatic vessels of the thigh; 19 - deep lymphatic vessels of the palm; 20 - deep inguinal lymph nodes; 21 - inferior ileal lymph nodes; 22 - deep lymphatic vessels of the forearm ; 23 - thoracic duct; 24 - intercostal lymph nodes; 25 - superficial ulnar lymph nodes; 26 - shoulder lymph nodes; 27 - subclavian trunk; 28 - jugular trunk; 29 - deep cervical lymph nodes; 30 - jugular-digastric lymph node; 31 - behind the lymph node; 32 - parotid lymph nodes.