General Information About Lymphs
1. Within the lymphoid tissue located anywhere in the body (lymph nodes, spleen, thymus and tonsilla).
2. Lymphocytes that are the product of Thymus in the myeloid tissue in the bone marrow are called T-lymphocyte, and lymphocytes that are the product of myeloid tissue are called B-lymphocytes.
Many lymph vessels are not seen in dissection, but they can be demonstrated in vivo by special methods.
Lymph capillaries begin with blunt ends in many tissues. They coalesce to form larger afferent veins. These vessels go to the nearest or regional lymph nodes.
As a rule, lymph passes through one or more lymph nodes before entering the bloodstream.
The wall of a lymph capillary is made of a single layer of endothelial cells, similar to blood capillaries. As the vessels enlarge, connective tissue appears in the wall. The largest lymphatic vessels are called truncus lymphaticus and ductus lymphaticus dexter. In their wall is also found in smooth muscles.
The vessels that carry lymph to the lymph nodes (nodules) are called afferent lymph vessels, and the lymph vessel coming out of the lymph node is called efferent lymph vessel. However, the effrent lymph vessel of one lymph node may be the afferent lymph vessel of another lymph node. After the lymph passes through one or more lymph nodes, it enters larger vessels called the truncus lymphaticus. These truncus also unite among themselves to form two large channels.
1. Ductius thoracicus.
2. Ductus lymphaticus dexter.
The first one opens to the corner where left V. jugularis interna and left V. subclavia join.
The right half of the head and neck, the right upper extremity, and the right upper half of the thorax drain lymph into the Ductus lymphaticus dexter, and the lymph from all remaining body parts drains into the Ductus thoracicus.
Superficial lymphatic vessels: they run through the skin or subcutaneous tissue. Lymph capillaries run parallel to the superficial blood vessels of the skin and merge between them to form larger vessels. The superficial lymphatic vessels eventually drain into the deep lymphatic vessels.
Deep lymphatic vessels: They course in the deep fascia and superficial fascia. They often accompany the large deep blood vessels. The walls of these lymphatic vessels are thick and contain connective tissue and smooth muscle fibers. They contain flaps.
Lymph Nodes (Nodules)
They are round, oval or bean-shaped structures. When they are swollen, they are easily palpated. Lymph nodes form important clusters in the axillary and inguinal region. Neck veins also make chains as companions.
Lymph nodes contain clusters of lymphatic tissue. They can vary in size from a pinhead to the size of a large bean.
Usually there is an indentation on one side of the knot, called the hilus. From here, blood vessels and nerves enter the node. The efferent vein of the node emerges from the hilus. The node is surrounded by a capsule. Afferent lymphatic vessels enter the node from anywhere in the periphery by perforating the capsule. Multiple afferent vessels can enter a node.
The node consists of an outer thick cortex and an inner darker medulla. There is no cortex in the hilus.
The capsule sends chambers called trabeculae into the node. Between the trabeculae, finer reticulum networks fill. Trabeculae and reticulum form the sponge-shaped skeleton of lymphoid tissue.
In the cortex, lymphocytes make lymph follicles. The medulla is made up of cell cords.
Reticuloendothelial cells are lined up along the trabeculae, as they pass through the lymph node, removing foreign matter from it. (For example, the lymph nodes of the lung clean the impurities in the cigarette smoke that the individual smokes and the dust he inhales).
Lymph is poured from the afferent vessels into the subcapsular space (sinus marginalis) below the cortex. After filtering between lymphatic and reticuloendothelial cells, it usually leaves the lymph node from a single efferent vessel and hilus, flowing either to another node or to larger lymphatic vessels.
Nerves entering the lymph nodes are exclusively vasomotor (they narrow and widen the lumen of blood vessels).
Lymph is collected from intercellular spaces in various tissues of the body.
Usually more tissue fluid is formed at the arteriolar end of a capillary bed than is absorbed at the venous end. This excess fluid is drained by lymph capillaries.
Functions of the Lymphatic System
1. Discharge of tissue fluid and protein: Lymph capillaries absorb plasma especially from the intercellular space and transfer this plasma to the venous circulation. During this transfer, the harmful substances in the lymph are phagocytosed by macrophages as it passes through its nodes. In the same way, bacteria and microorganisms taken from an infected area are also captured and prevented from entering the bloodstream.
2. Fat absorption and transmission: The lymph vessels of the small intestine are specifically called lacteal. The lymph circulating in these vessels is milky white in color and is called chylus.
Chylus contains fat, fatty acids, glycerol, amino acids, glucose and other substances (eg drugs) absorbed from the intestines.
3. Contribution to the body defense mechanism: The lymphatic system contains a large part of the immune mechanism, which is very important for the body. A specific antibody is prepared by immunologically responsible cells against a small amount of foreign protein that enters the lymph capillary from the infected area, or lymphocytes directly reach the infection site through blood vessels and tissue fluid. This is called the humeral mechanism of the immune response. If foreign tissue is transplanted into the organism (organ transplantation), lymphocytes work to reject the transplanted foreign tissue.
Clinical Significance
1. The lymph nodes related to the lymphatic vessels draining the lymph of an infected area are often inflamed. Inflammation of the lymph vessels is called lymphangitis.
2. Eggs of a parasite called Microfilaris nocturum can enter lymphatic vessels and block large vessels. As a result, body parts such as the legs and the scrotum in men can become extremely enlarged. This disease is called Elephantiasis (Elephant disease).
3. Cancer cells can also cause occlusion of lymphatic vessels and edema.
4. Swelling of the upper extremities may occur due to insufficient lymph flow as a result of removal of many lymph nodes in surgeries such as radical mastectomy.
5. The lymphatic system is an important pathway in the metastasis (spread) of cancer cells. This condition is called lymphogenic metastasis of malignant cells. If the sponge-shaped skeletal structure of the lymph nodes is remembered, it will be immediately understood that a cancer cell that mixes with the lymph can easily attach and reproduce in the lymph node.
6. The study of making lymph vessels and nodes visible on X-ray is called lymphangiography. This can only be achieved by cannulating a peripheral lymph vessel and injecting a radiopaque substance into it.
Local Lymph Nodes
The lymph nodes in our body are examined under six main headings: lymph nodes of the lower side, pelvis, abdomen, chest, head and neck.
1. Lower side lymph nodes: They form three groups as inguinal, popliteal and anterotibial. Inguinal lymph nodes consist of 12-16 lymph nodes, 1-3 of which are deep. Superficial inguinal lymph nodes collect lymph from the free inferior side, external genitalia, and anterior wall of the hip and abdomen. There are 6-7 popliteal lymph nodes in the poplitea, and they send the lymph they receive from the feet and legs to the inguinal lymph nodes
.
Lymphonodi inguinalis superficialis Clinical Information
1. Because superficial lymph nodes are located very superficially, they can be palpated even if they do not undergo pathological changes.
2. The study of making lymph nodes visible radiologically is called lymphangiography. Trypan blue injected under the skin on the back of the foot makes the lymph vessels visible. A radiopaque substance is injected into the visible vein.
3. It is clinically important to know that the inguinal lymph nodes not only receive lymph from the lower extremities, but also lymph from the external genitalia, anal canal and perineum, and partly the uterus.
Minor sepsis from the lower extremity can swell these nodes, as well as cancers of the external genital organs and anal canal or perineum abscesses can swell these lymph nodes.
2. Pelvic lymph nodes: They are examined in two groups as parietal and visceral. The parietal group is found along the iliac vessels near the visceral group pelvis organs (eg Lymphonodi paravesiculares, Lymphonodi pararectales). The lymph of these nodes flows to Cisterna chyli via Truncus lumbalis via the lumbar nodes. The inferior lymphatics connect to the pelvic lymph nodes.
3. Abdominal lymph nodes: The lymph of the anterior and lateral walls of the abdomen reaches two separate groups of regional lymph nodes. Those above the umbilicus flow into the axillary lymph nodes, and those below the navel into the inguinal lymph nodes. The lymph nodes of the abdominal cavity are examined in two groups as parietal and visceral. Parietal group is located around V. cava inferior and Aorta abdominalis (Lymphonodi lumbales), while visceral group is located around Truncus coeliacus A. mesenterica superior et interior. Efferents of lumbal lymph nodes flow to Truncus lumbalis-Cisterna chyli, and efferents of visceral lymph nodes flow to Cisterna via Truncus intestinalis.
4. Chest lymph nodes: The lymph nodes of the chest wall constitute the parietal group, and the lymph nodes near the organs in the chest cavity form the visceral group. Parietal group includes parasternal, intercostal and diaphragmatic lymph nodes, visceral group lymph nodes are located in the superior and posterior mediastinum, Arcus aortae, Trachea, bronchi and around the Ocephagus. The efferents of these lymph nodes flow to Ductus.thoracicus and Ductus lymphaticus dexter via Truncus bronchomediastinalis.
5. Upper lymph nodes: Lymph vessels that begin to form on the back of the hand and palm on the upper side reach the regional lymph nodes by following two superficial and deep paths. The first stop is the cubital, and the second is the axillary lymph nodes. Axillary lymph nodes, which are an important regional lymph node community, are located in 5 groups (apical, central, lateral, subscapular and pectoral lymph nodes). Ductus on the left, via efferents Truncus subclavius. thoracicus reaches the Ductus lymphaticus dexter on the right.
6. Head and neck lymph nodes: After the mesentery lymph nodes, the most crowded lymph node collection in the human body is found in the head and neck. These nodes form two horizontal and three vertical chains. The upper horizontal chain contains the occipital, mastoid, parotideal, facial, submental and submandibular lymph nodes, while the lower horizontal chain contains the supraclavicular and scalene lymph nodes. Vertical chains are formed by superficial and deep neck lymph nodes (Lymphonodi cervicales superficiales et profundi). The head and neck lymphatics finally terminate in the Truncus jugularis.
Thymus (Thymus): The thymus is the main organ of the lymphatic system located in the anterior upper part of the chest cavity. The size of the thymus, which consists of two lobes, right and left, changes with age. At two years of age, it is the largest size relative to its body mass, with an average weight of 12 g. It grows until puberty and reaches 30-40 grams. It gradually shrinks after puberty. (involutio) The thymus lobes in pyramidal shape are surrounded externally by a connective tissue capsule. The thymus tissue is divided into lobes of 1-2 mm in size with the partitions (trabecula) separated from the capsule. The peripheral part of each lobulus is densely filled with small lymphocytes. This area is called the cortex. The central parts of the lobules (medulla) are poor in lymphocytes and contain Hassal bodies formed by epithelioreticulocytes.
Thymus, made in the bone marrow, sensitizes the lymphocytes that come to it with specific antigen and transforms them into T lymphocytes. T lymphocytes live for years and provide cellular immunity.
Thymus also, thymosin, alpha thymosin, β 1.2…5.timopoietin, I-II thymic humoral hormone (THH). secretes hormones such as thymostimulin and factor thymic serum (FTS).
Tonsils (Tonsils): In the passage from the mouth and nose to the pharynx, the lymph follicles under the mucosa are very developed, they have pushed the mucosa and become macroscopically visible. These are called tonsils.
Tonsillar produce lymphocytes, these lymphocytes pass through the mucosa into the oral and pharyngeal cavities. Six tonsils, consisting of tonsilla pharyngealis (adenoidea), tonsilla tubaria, tonsilla palatina and tonsilla lingualis, located at the entrance of the pharynx, form an uninterrupted defense ring.
Appendix vermiformis is also called Tonsilla abdominalis by some Anatomists because it contains a very dense lymphoid tissue.
Spleen (Splen, Lien): It is a large vascular lymphatic organ. It is located in the upper left corner of the abdominal cavity and below the diaphragm. It is the largest lymphoid tissue mass in the body. Normally, it cannot be palpated externally. However, if it grows in some diseases, it can be felt under the ribs. The side of the spleen facing the diaphragm is convex and flat. On the side facing the organs, there are both traces of organs and a hollow area called the hilus (navel). From the hilus, vessels and nerves enter the organ
The spleen is soft, multi-vascular and dark red in color. It is responsible for the destruction of erythrocytes (red blood cells) and the preparation of new hemoglobin from iron. In addition, it filters damaged, dysfunctional blood cells and platelets from the blood. Foreign particles, bacteria and viruses in the blood initiate the immune response in the spleen, revealing cellular and humoral immune responses. Similar to lymph nodes acting as an immunological filter of lymph, the spleen functions as an immunological filter of blood.
The spleen is an important phagocytic and immune organ. In the case of its removal for any reason or its congenital absence, it causes some characteristic changes in the blood, although it does not cause a remarkable clinical problem. For example, splenic anemia.
The spleen is dark red in color, weighs 100-200 grams depending on the amount of blood it carries, and measures approximately 4 x 8 x 12 cm. The spleen tissue, which is divided by trabeculae sent by its fibrous capsule, consists of two types of lymphoid masses called white and red pulp. White pulp. Lymphonodi splenicus (Malpighi follicles), red pulp is made of lymphoid cords (Chorda splenica – Billroth cords).
Spleen Clinical Information
1 If part of the spleen is removed, it regenerates very quickly. However, even removal of the entire spleen (splenectomy) does not cause much functional impairment.
2. Splenomegaly is a phenomenon of overgrowth of the spleen. The diseased spleen can reach 10 times its normal size. In this case, it completely fills the left half of the abdominal cavity. When the spleen enlarges, it descends below the left costal margin and its notched upper edge faces downward and inward. When the patient breathes deeply, this notched edge moves down and forward and can be palpated from the abdomen.
3. Trauma, tumors, some hematological diseases may require removal of the spleen. During this operation, which we call splenectomy, the surgeon must be careful not to injure the tail of the pancreas that touches the spleen.
4. Although the spleen is well protected by the ribs, it is an organ that is easily torn in case of blows to the abdomen. In splenic rupture, there is excessive intraperitoneal bleeding and the patient may go into shock.
5. In infectious mononuclease, malaria or septicemia, the spleen may rupture spontaneously because the spleen grows too large, this is called spontaneous spleen rupture.
6. Lienis accessorius: 10% of people
have one or two small extra spleens. These are 1 cm. They are found in diameter and embedded in the tail of the Pancreas. Sometimes they are also located between the two leaves of the gastrolienal ligament.
In a disease with an indication for removal of the spleen, such as splenic anemia, the symptoms of the disease continue after surgery if these accessory spleens are not removed as well.
7. We can see the spleen radiologically with a method we call splenoportography. For this, a radiopaque substance is injected into the spleen. In addition, a needle biopsy of the spleen can be easily performed. However, it is very important to keep in mind the relationship of the spleen with Recessus costodiaphragmaticus during these procedures. This recessus is mid-axillary or even at the level of the 10th costa. Pneumothorax may occur if the pleural cavity is entered through the recessus with a needle.
Wishing you a healthy day…
Specialist Dr.Ali AYYILDIZ – Veterinarian – Human Anatomy Specialist Dr.(Ph.D.)
