Lymphatic System Spring 2024 Anatomy PDF

Cristian Dezdrobitu, DVM, MSc, PhD 1 Assistant Professor The lymphatic system has two components: 1. The first is a system of lymphatic capillaries and larger vessels that return interstitial fluid to the bloodstream. 2. The second comprises a variety of widely scattered aggregations of lymphoid tis...

Cristian Dezdrobitu, DVM, MSc, PhD 1 Assistant Professor The lymphatic system has two components: 1. The first is a system of lymphatic capillaries and larger vessels that return interstitial fluid to the bloodstream. 2. The second comprises a variety of widely scattered aggregations of lymphoid tissue, including the many lymph nodes and less discrete lymphoid aggregations, such as tonsils. 2 LYMPHATIC SYSTEM: Is part of the vascular system Is an important part of the immune system (provides specific and nonspecific defence mechanisms) Formed by a large network of lymphatic vessels that carry a clear fluid called lymph directionally towards the heart (right atrium) Lympha (Latin) meaning "water“ The circulating lymphocytes (T and B), as well as the lymphocytes and plasma cells spread across the body, also participate in this protective system https://commons.wikimedia.org/wiki/File:Do g_heart_2.jpg 3 LYMPHATIC SYSTEM: It includes all the lymphatic organs: thymus tonsils spleen lymph nodes hemal nodes the diffuse lymphatic tissue lymphatic nodules 4 Thymus – lobed organ with temporary function, placed in the cervicothoracic area (different topography in species), starting from the dorsal sternal aspect towards the ventral cervical area. THYMUS IN FOAL Konig, 2004 5 Tonsils - less discrete lymphoid aggregations DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 6 The spleen part of the lymphoepithelial system placed at the level of the abdominal cavity, in relationship with the stomach importance in storage, release and concentration of the erythrocytes produce lymphocytes and monocyte 7 The spleen of the dog Hemal nodes are small lymphatic bodies resembling lymph nodes in their structure thin capsule present found in the course of blood vessels are not found in all species and are most familiar in sheep the afferent and efferent lymphatics are absent (NO lymphatic vessels) found in some animals in relation to their abdominal and thoracic viscera hemal nodes may represent an intermediate stage between a lymph node and the spleen https://www.researchgate.net/figure/Anatomical-view-ofhemal-nodes-in-Saanen-goat_fig1_327476343 8 The diffuse lymphatic tissue and lymphatic nodules present in many mucous membranes (larynx, intestine, prepuce, and vagina and other parts of the female tract) no capsule present MALT - also called mucosa-associated lymphatic tissue MALT plays a role in regulating mucosal immunity: It may be the site of lymphoma, usually non-Hodgkin lymphoma A specific entity is the MALT lymphoma linked to Helicobacter pylori in the stomach. 9 LYMPH TISSUE 3 types  Diffuse lymphatic tissue  No capsule present  Found in connective tissue of almost all organs  Lymphatic nodules  No capsule present  Oval-shaped masses  Found singly or in clusters (Peyer's patches are clusters of lymphatic nodules that occur in the mucosa that lines the ileum of the small intestine)  Lymphatic organs  Capsule present  Lymph nodes, spleen, thymus gland 10 LYMPHATIC CIRCULATORY SYSTEM What does the lymphatic circulatory system mean? A: Network of lymph vessels and lymph nodes Role? A: Collects interstitial fluid (fluid found in the spaces around cells), waste material, and other things (like viruses and bacteria) that are in the body tissues, outside the bloodstream. A: Vessels carry the clear watery fluid called lymph. Lymph??!! A: ultrafiltration of the blood plasma; lymph is the term used to describe interstitial fluid once it has entered the lymphatic system. Lymph is similar in composition to blood plasma, but has less protein. 11 What is the role of the lymph vessels? A: Lymph vessels draw up the lymph fluid from around the cells to send it towards the chest. There, lymph fluid collects into a large vessel (Chyli cistern, thoracic duct) that drains into the cranial vena cava that opens in the heart. !!!!Lymph fluid would build up and cause swelling if it were not drained in some way. That’s the role of the lymph vessels!!!! Lymph nodes and what they do A: Small structures placed on the trajectory of the lymph vessels that work as filters for harmful substances. They contain immune cells that can help fight infection by attacking and destroying germs that are carried in through the lymph fluid. A: Compared by anatomists with a pearl chain A: Usually placed in relations with different arteries and veins 12 Lymphatic capillaries are interlaced with the arterioles and venules of the cardiovascular system. Collagen fibers anchor a lymphatic capillary in the tissue (inset). Interstitial fluid slips through spaces between the overlapping endothelial cells that compose the lymphatic capillary. 13 afferent lymphatic vessels: lead into a lymph node efferent lymphatic vessels: lead out of a lymph node https://en.wikipedia.org/wiki/Superf icial_cervical_lymph_nodes#/media/ File:Gray602.png 14 Why it is important to include the lymph nodes in the examinations of the small animals and not only? A: When there’s a problem, such as infection, injury, or cancer, immune-mediated diseases, allergic reactions, skin diseases the node or the group of lymph nodes in that area may swell or enlarge as they work to filter out the “bad” cells. This may be called lymphadenopathy. Swollen lymph nodes tell you that something is not right, but other symptoms help pinpoint the problem. For instance, ear pain, fever, and enlarged lymph nodes near the patient ear are clues that the patient may have an ear infection. A: one of the principal way for the spread of cancer 15 Examination of the palpable lymph nodes in dogs Source: Veterinary Anatomy - The CardioCirculatory System - Alexandru Gudea, Cristian Dezdrobitu, Florin Stan, Cristian Martonos parotidian Source: Veterinary Anatomy - The CardioCirculatory System - Alexandru Gudea, Cristian Dezdrobitu, Florin Stan, Cristian Martonos https://www.slideshare.net/GansbaaiSA/examination-ofsuperficial-lymph-nodes-in-dogs-and-cat lateral retropharyngeal 16 Palpable lymph nodes of the dog Parotid lateral retropharyngeal (inconstant) superficial inguinal (mammary-female; scrotal-male) mandibular femoral (inconstant) superficial cervical (prescapular) popliteal axillary accessory axillary (inconstant) DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 17 Can veterinarians palpate all lymph nodes? A: No, because they are palpable only in the loose subcutaneous tissues Things we need to know before examinations: 1) size will vary with location, age and species 2) been shaped and smooth contour 3) some of them are hard to locate 20 Classification of lymph nodes in relation to their topography  The Lymph Nodes of the Head  The Lymph Nodes of the Neck  The Lymph Nodes of the Forelimb  The Lymph Nodes of the Thorax  The Lymph Nodes of the Abdominal Viscera and Loins  The Lymph Nodes of the Hindlimb, Pelvis, and Abdominal Wall 26 The topography of the palpable lymph nodes in canines The mandibular lymph center presents a single group of mandibular lymph nodes palpable at angle of jaw they are 2-4 in number situated caudo-ventrally to the angle of the mandible, in the angle between the masseter muscle and the mandibular salivary gland covered by the skin and the cutaneus muscle of the face The parotidian lymph center represented usually by a single lymph node 1-2 centimeters long but very rare can be two also situated near the base of the ear, close to the temporo-mandibular joint and covered partly by the parotid salivary gland his anterior part covers the caudal margin of the masseter muscle easy palpable on a live dog 27 The topography of the palpable lymph nodes in canines The retropharyngeal lymph center comprises two groups of nodes regarding their topography, medial and lateral the lateral retropharyngeal lymph node appears rarely, double or triple and small, placed ventral and medial in relation with the wing of the atlas is palpable on a live dog The superficial cervical lymph center (prescapular) placed cranial to the supraspinous muscle and to the shoulder approachable through the regional skin The axillary lymph center comprises the proper axillary lymph node and the accessory axillary lymph node the latter lymph node is almost all the time absent (caudal to the former one, on the ventral margin of the latissimus dorsi m. if present) the former one is placed medial to the shoulder joint, in a mass of fat tissue medially to the distal part of the teres major muscle being easily palpated through the skin when the forelimb is in anterior extension 28 The topography of the palpable lymph nodes in canines The ilio-femoral lymph center (deep inguinal - old term) very reduced in size and inconstant when present it has two lymph nodes: the ilio-femoral lymph node placed at the termination of the external iliac artery close to the femoral artery and the femoral lymph node placed in the distal part of the femoral triangle The inguino-femoral lymph center (superficial inguinal –old term) comprises in dog, the scrotal lymph nodes - palpable on the dorsolateral surface of the penis, 1 centimeter cranial to the spermatic cord, close to the lower part of the preputial cavity, embedded in fat tissue in bitch, the mammary lymph - one, two or three normally palpable and placed on the dorso-lateral margin of the last mammary gland, 2-3 centimeters from the cranial margin of the pubis bone 29 The topography of the palpable lymph nodes in canines The popliteal lymph center presents only the superficial popliteal lymph node, mostly just one sizes ranged between 1-4 centimeters long placed caudal to the stifle joint, on the caudal surface of the gastrocnemius muscle, between the biceps femoris and semitendinosus muscles being superficially placed are easily palpable through the skin even they are embedded in fat tissue 30 OBJECTIVES  Understand the role of the Lymphatic System  Describe the two major components of the Lymphatic System  Describe the lymphatic organs  Comprehend the 3 types of lymph tissue  Define the Lymphatic Circulatory System (lymphatic vessels, lymph and lymph nodes)  Understand why it is important to include the lymph nodes in the examinations of animals  Describe the topography of the palpable lymph nodes in canines 31 1. The lymph node indicated by the arrow is the: A. Mandibular B. Lateral retropharyngeal C. Superficial inguinal D. Popliteal E. Superficial cervical (prescapular) 2. Choose the correct location to palpate the proper axillary lymph node: A. Medial to the inguinal region B. Medial to the patella C. Medial to the shoulder joint D. Ventral and medial in relation with the wing of the atlas E. Caudal to the stifle joint 3. Please choose the correct statement regarding the lymphatic system: A. Is part of the vascular system B. Is part of the immune system C. Is formed by a network of lymphatic vessels that carry lymph D. All the above E. Is formed by a network of vessels that carry blood