3- Lymphatic system and Thoracic Anatomy.pptx

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1. Lymphatic system and Thoracic Anatomy

2. 1- What is the lymphatic system? 2- Function of the lymphatic system 3- Components of the lymphatic system 4- Clinical Significance of the Lymphoid System

3. WHAT IS THE LYMPHATIC SYSTEM? The lymphatic system is part of the circulatory system and an important part of the immune system, comprising a network of lymphatic vessels that carry a clear fluid called lymph (from Latin, lympha meaning "water ”) directionally toward the heart.

4. The  lymphatic system , also known as the lymphoid system, is a complex system that consists of a network of  lymphatic vessels  (including capillaries, tracts, and ducts) and various  lymphoid organs. Through the lymphatic system flows yellowish lymphatic fluid called  lymph , and lymphoid organs produce and store lymphatic cells (lymphocytes). Additionally, lymph is filtered through various lymphoid tissue collections called lymph nodes.

5. Functions of lymphatic system

6. Roles of the Lymphatic System One-way drainage system. 2) Lipid Absorption from Small Intestine. 3) Produce & circulates Immune cells.

7. Components of the Lymphoid System Lymphatic Plexuses Networks of lymphatic capillaries that originate blindly in the extracellular spaces of most tissues, formed of highly attenuated endothelium lacking a basement membrane. Lymphatic Vessels A nearly bodywide network of thin-walled vessels with abundant valves, giving them a characteristic beaded appearance in living individuals. Lymph The clear, watery, slightly yellow tissue fluid that enters lymph capillaries by diffusion, as it is blind ended, and is conveyed by lymphatic vessels, similar in composition to blood plasma (90% water, 10% other dissolved substances as lymphocytes, bacteria, cellular debris, fats, cancerous cells, and proteins) Lymph Nodes Small masses of lymphatic tissue located along lymphatic vessels that filter lymph on its way to the venous system. 1 2 3 4

8. Lymphocytes These circulating cells of the immune system react against foreign materials, providing crucial defense mechanisms. Lymphocytes are produced by lymphoid organs and circulate throughout the body, ready to respond to potential threats. Lymphoid Organs These specialized body parts produce lymphocytes and include: Thymus Red bone marrow Spleen Tonsils (palatine, pharyngeal and ligual ) Solitary and aggregated lymphoid nodules in the alimentary tract Appendix 5 6

9. Valves in lymphatic vessels prevent backflow of lymph.

10. Lymph capillaries unite to form lymphatic vessels. Thin-walled vessels . Beaded appearance . The flow of lymph in lymphatic vessels is unidirectional . The lymphatic vessels pass through a series of lymph nodes before lymph is drained into the venous system. 1- LYMPH VESSELS

11. Lymph lymph is tissue fluid that has entered the lymphatic vessels excess tissue fluid functions: transports proteins and other molecules to the bloodstream moves foreign particles to lymph nodes

12. According to location, lymph vessels are divided into two types:- Superficial lymph vessels Deep lymph vessels Superficial and deep lymph vessels

13. Lymphatic Vessel Distribution Widespread Distribution Lymphatic capillaries and vessels occur almost everywhere blood capillaries are found, creating a parallel drainage system throughout most of the body. Notable Exceptions Several areas lack lymphatic vessels, including teeth, bone, bone marrow, and the entire central nervous system . In the CNS, excess tissue fluid drains into the cerebrospinal fluid instead. Superficial Lymphatics More numerous than veins in the subcutaneous tissue, these vessels anastomose freely, converge toward, and follow venous drainage. At the end, they drain into deep lymphatic vessels.

14. Deep lymphatic vessels They accompany the arteries and receive the drainage from the superficial lymph vessels and also from internal organs. Likely, the deep lymphatic vessels are also compressed by the arteries they accompany, milking the lymph along these valved vessels

15. Lymphatic Drainage Pathways Lymphatic Capillaries Collect excess interstitial fluid and proteins from tissues Lymphatic Vessels Transport lymph through a series of valves, often alongside blood vessels Lymph Nodes Filter lymph as it passes through, removing foreign materials Lymphatic Trunks Larger collecting vessels that receive lymph from multiple regions Return to Bloodstream through (Right lymphatic duct and Thoracic duct) Via the right lymphatic duct or thoracic duct into venous angles

16. Lymphatic ducts

17. Thoracic duct Length-45cm Ascends through the diaphragm and passes upwards in the thoracic cavity. It empties at the left subclavian vein. It drains Lymph from Lower extremites Abdomen Left Thoracic region Left side of Head & Neck Left upper Limbs.

18. THE RIGHT LYMPHATIC DUCT It lies in the root of the neck and opens into the right subclavian vein. It drains lymph from: 1- Right thoracic region 2- Right side of the head and neck 3- Right upper limb

19. Lymphoid Tissues: Un-encapsulated lymphatic tissues Tonsils Pharyngeal 2) Palatine 3) Lingual Tonsil located in strategic locations

20. Lymphoid Tissues

21. Lymphoid Organs: Surrounded by fibrous capsule ( encapsulated ) Lymph Nodes Thymus Spleen

22. Structure of a Lymph Node

23. Various Lymph Nodes Cervical lymph nodes Axillary lymph nodes Inguinal lymph nodes Popliteal lymph nodes Thoracic lymph nodes Lumbar lymph nodes Pelvic lymph nodes

24. The Thymus Behind the sternum (in mediastinum). larger in children and disappears at puberty. site of T cell maturation.

25. The Spleen Largest lymphoid tissue in the body

26. The Spleen Functions : Removes old & abnormal blood cells. Stores Iron (Fe) from recycled RBCs. Can initiate immune response (via T-cells B-cells). 4) Hematopoietic organ. Can store ~30% of RBC volume for emergency release

27. Clinical Significance of the Lymphoid System Diagnostic Value Enlarged lymph nodes (lymphadenopathy) often indicate infection or disease in the area they drain, making them valuable diagnostic indicators. Clinicians routinely check superficial lymph nodes during examinations. Lymphedema Disruption of lymphatic drainage can lead to lymphedema, a chronic condition characterized by swelling due to accumulated lymph fluid. This may result from surgery, radiation, infection, or congenital abnormalities. Cancer Spread Cancer cells can use lymphatic vessels as pathways for metastasis, spreading to lymph nodes before reaching other parts of the body. Understanding lymphatic drainage patterns is crucial for cancer staging and treatment planning.

28. Thorax

29. Thorax Thoracic wall Ribs (Typical and Atypical) Costal cartilages Intercostal spaces Thoracic vertebrae Attachment of ribs with the vertebrae Sternum Superior thoracic aperture Inferior thoracic aperture

30. Thorax (overview) The  thorax  is the superior part of the trunk extending between the neck and the abdomen. It consists of several  components : Thoracic wall Several cavities Nerves, blood vessels, lymphatics Internal organs Breasts

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35. Thoracic wall The  thoracic wall  consists mainly of  muscles  and bones that form the  thoracic cage . Overall, the thoracic wall is formed by the following structures: Anteriorly   -  sternum ; also called the breastbone; it is located in the anterior midline of the thorax and consists of three parts. Laterally  - twelve  ribs   on each side and three layers of   intercostal muscles ; (external, internal, and innermost intercostal muscles). Posteriorly   - twelve  thoracic vertebrae  and their  intervertebral discs .

36. Thoracic cage The  thoracic cage  (also known as the  rib cage ) is a bony framework of the  thoracic wall . It encloses the thoracic cavity and is composed of various bones, cartilages, and joints. The following structures form the thoracic cage: Anteriorly  -  sternum Laterally  - twelve pairs of  ribs and   their respective  costal cartilages . Posteriorly  - twelve   thoracic vertebrae .

37. ANATOMY OF THE RIBS The ribs are a set of twelve paired bones that form the protective ‘cage’ of the  thorax . They articulate with the vertebral column posteriorly and terminate anteriorly as cartilage (known as costal cartilage). As part of the bony thorax, the ribs protect the internal thoracic organs. They also have a role in ventilation, moving during chest expansion to enable lung inflation.

38. RIB STRUCTURE There are two classifications of ribs : atypical and typical . The typical ribs have a generalized structure, while the atypical ribs have variations on this structure. 1-TYPICAL RIBS: The typical rib consists of a head, neck and body: The  head  is wedge shaped, and has two articular facets separated by a wedge of bone. One facet articulates with the numerically corresponding vertebra , and the other articulates with the vertebra above. The  neck  contains no bony prominences but simply connects the head with the body. Where the neck meets the body there is a roughed tubercle with a facet for articulation with the transverse process of the corresponding vertebra. The body, or   shaft   of the rib is flat and curved. The internal surface of the shaft has a groove for the neurovascular supply of the thorax, protecting the vessels and nerves from damage.

39. 2-Atypical Ribs: Ribs 1, 2, 10, 11 and 12 can be described as ‘atypical’ – they have features that are not common to all the ribs. Rib 1   is shorter and wider than the other ribs. It only has one facet on its head for articulation with its corresponding vertebra. The superior surface is marked by two grooves, which make way for the subclavian vessels. Rib 2  is thinner and longer than rib 1 and has two articular facets on the head as normal. It has a roughened area on its upper surface from which the  serratus anterior  muscle originates. Rib 10  only has one facet – for articulation with its numerically corresponding vertebra. Ribs 11  and   12   have only one facet, which is for articulation with their corresponding vertebra. And both have no neck,

40. The 1st rib It is the broadest (i.e., its body is widest and nearly horizontal), shortest, and most sharply curved of the seven true ribs. It has a single facet on its head for articulation with the T1 vertebra only and two transversely directed grooves crossing its superior surface for the subclavian vessels; the grooves are separated by a scalene tubercle a nd ridge, to which the anterior scalene muscle is attached.

41. The 2nd rib It has a thinner, less curved body and is substantially longer than the 1st rib. Its head has two facets for articulation with the bodies of the T1 and T2 vertebrae ; its main atypical feature is a rough area on its upper surface, the tuberosity for serratus anterior , from which part of that muscle originates.

42. The 10th–12th ribs, like the 1st rib, have only one facet on their heads and articulate with a single vertebra. The 11th and 12th ribs are short and have no neck or tubercle.

43. Costal cartilages - They prolong the ribs anteriorly and contribute to the elasticity of the thoracic wall. - These cartilages increase in length through the first 7 ribs and then gradually decrease. - The first 7 costal cartilages attach directly to the sternum, while the 8th, 9th, and 10th articulate with the costal cartilages just superior to them, forming a costal margin. - The 11th and 12th costal cartilages form caps on the anterior ends of the corresponding ribs and do not reach or attach to any other bone or cartilage.

44. Intercostal spaces They separate the ribs and their costal carilages from one another. The spaces are named according to the rib forming the superior border of the space —for example, the 4th intercostal space lies between ribs 4 and 5. There are 11 intercostal spaces. Intercostal spaces are occupied by intercostal muscles and membranes and two sets of intercostal blood vessels and nerves, which have the same number assigned to the space. The space below the 12th rib does not lie between ribs and thus is referred to as the subcostal space.

45. Thoracic vertebrae

46. Thoracic Vertebrae - The twelve  thoracic vertebrae  are medium-sized and increase in size from superior to inferior. -Their function is to articulate with ribs, producing the bony thorax. - Each thoracic vertebra has two ‘ demi facets, ’ superiorly and inferiorly placed on either side of its vertebral body. The demi facets articulate with the heads of two different ribs. - On the  transverse processes  of the thoracic vertebrae, there is a costal facet for articulation with the shaft of a single rib . For example, the head of Rib 2 articulates with the inferior demi facet of thoracic vertebra 1 (T1) and the superior demi facet of T2, while the shaft of Rib 2 articulates with the costal facets of T2. The spinous processes  of thoracic vertebrae are oriented obliquely inferiorly and posteriorly . In contrast to the cervical vertebrae, the vertebral foramen of thoracic vertebrae is  circular.

47. Thoracic Vertebrae The 12 thoracic vertebrae (T 1 - T 12 ) are almost typical. They are larger than the cervical vertebrae. The body is somewhat heart- shaped and has two costal demifacets (articulating surfaces) on each side, which receive the heads of the ribs. Demi= not complete The spinous process is long and hooks sharply downward. heart- shaped Thoraci c vertebra

48. Atypical thoracic vertebrae have costal facets in place of demifacets : • The superior costal facets of vertebra T1 are not demifacets because there are no demifacets on the C7 vertebra above, and rib 1 articulates only with vertebra T1. • T10 has only one bilateral pair of (whole) costal facets. • T11 and T12 also have only a single pair of (whole) costal facets.

49. Attachment of ribs with the vertebrae - Costovertebral joint - Costotransverse joint

50. Sternum

51. Sternum The  sternum , also called the breastbone, is a relatively small, somewhat T-shaped bone that lies in the  anterior midline of the thorax . It participates in forming the  anterior wall of the thoracic cage  and is connected directly or indirectly to the  ribs  via their costal cartilages. 1- The sternum protects the internal organs of the thorax, such as the  heart  and  lungs , from mechanical injury. 2- It provides attachment sites for various muscles and ligaments.

52. The sternum consists of three parts: manubrium, body, and xiphoid process. In adolescents and young adults , the three parts are connected together by cartilaginous joints that ossify during middle to late adulthood.

53. Manubrium   - broad most superior portion; this part is massive and appears quadrangular-shaped with four borders; it is also the thickest and widest part of the bone; it articulates with both  clavicles  and the  first ribs ; Jugular notch  - a midline depression that is found at the center of the superior border of the manubrium; it is also known as the suprasternal notch; Clavicular notches  - two indentations that are found at the superior corners of the manubrium; they are located on either side of the jugular notch; these notches serve as the sites at which the left and right clavicles connect with the sternum, forming the sternoclavicular joints. First costal notches  - two indentations that are found on the sides of the manubrium below the clavicular notches; they serve as the sites at which the  cartilages of the first ribs  attach to the manubrium .

54. Body (corpus)   -   middle and central portion of the sternum that articulates with the second to seventh ribs; it is the longest part . Costal notches  - several depressions that are found on the sides of the body; they represent the articulation sites for the costal cartilages of the second to seventh ribs. Transverse ridges  - they represent the lines of fusion between the sternal segments and can be seen as horizontal lines on the anterior surface of the bod.

55. Xiphoid process (xiphisternum)   - narrow triangular-shaped tip of the sternum; it is the most inferior part that appears pointed; it is also the most variable portion and is often fused together with the body. The lower border of the manubrium articulates with the superior border of the body, forming an angle called the  sternal angle . The articulation between the manubrium and the body is called the manubriosternal joint, while the joint between the body and the xiphoid process is known as the  xiphisternal joint.

56. Structures that pass through it are the trachea, esophagus, nerves, and vessels that supply and drain the head, neck, and upper limbs.

57. Its Relations Posteriorly, the 12th thoracic vertebra. Posterolaterally , by the 11th and 12th pairs of ribs. • Anterolaterally, by the joined costal cartilages of ribs 7–10, forming the costal margins. • Anteriorly, by the xiphisternal joint. Structures pierce the diaphragm as (esophagus and inferior vena cava), or pass posterior to it (e.g., aorta).

58. Mediastinum

59. The mediastinum is the  central compartment  of the thoracic cavity, located between the two pleural sacs. It contains most of the thoracic organs . Anatomically, the mediastinum is divided into two parts by an imaginary line that runs from the  sternal angle  (the angle formed by the junction of the sternal body and manubrium) to the T4 vertebrae: Superior mediastinum   – extends upwards, terminating at the superior thoracic aperture. Inferior mediastinum   – extends downwards, terminating at the diaphragm. It is further subdivided into the anterior mediastinum, middle mediastinum and posterior mediastinum.

60. - The superior mediastinum extends inferiorly from the superior thoracic aperture to the horizontal plane that includes the sternal angle anteriorly to the junction (IV disc) of T4 and T5 vertebrae posteriorly, often referred to as the transverse thoracic plane. - The inferior mediastinum —between the transverse thoracic plane and the diaphragm—is further subdivided by the pericardium into anterior, middle, and posterior parts. - The pericardium and its contents (heart and roots of its great vessels) constitute the middle mediastinum. - Some structures, such as the esophagus, pass vertically through the mediastinum and therefore lie in more than one mediastinal compartment.

61. Pericardium

62. The pericardium is a  fibro-serous , fluid-filled sack that surrounds the muscular body of the heart and the roots of the great vessels (the aorta, pulmonary artery, pulmonary veins, and the superior and inferior vena cavae ). The pericardium is made up of two main layers: a tough external layer known as the  fibrous pericardium,  and a thin, internal layer known as the  serous pericardium

63. Pericardium The pericardium consists of  two layers  -  fibrous or the outermost layer  and the  serous or the innermost layer . The serous layer is a double layer, and it is composed of two sublayers ( parietal  and  visceral ). Between both sublayers of the serous pericardium is a potential space known as the  pericardial cavity . It contains the pericardial fluid. Its main function is to lubricate both sublayers and reduce friction between them when the heart contracts.

64. Functions The pericardium has many physiological roles, the most important of which are detailed below: Fixes the heart  in the mediastinum and limits its motion. Prevents overfilling  of the heart. This is done by t he inextensible fibrous layer of the pericardium, which prevents the heart from increasing in size too rapidly . Lubrication . A thin film of fluid between the two layers of the serous pericardium reduces the friction. Protection from infection . The fibrous pericardium serves as a physical barrier between the muscular body of the heart and adjacent organs prone to infection, such as the lungs.