Spleen- anatomy physiolog, function, anomalies.pptx

Lecture notes for medical students

1. Tips on using my ppt. You can freely download, edit, modify and put your name etc. Don’t be concerned about number of slides. Half the slides are blanks except for the title. First show the blank slides (eg. Aetiology ) > Ask students what they already know about ethology of today's topic. > Then show next slide which enumerates aetiologies. At the end rerun the show – show blank> ask questions > show next slide. This will be an ACTIVE LEARNING SESSION x three revisions. Good for self study also. See notes for bibliography.

2. Introduction & History.

3. Introduction & History. The spleen is a shoe shaped organ located in the left hypochondrium and partly in the epigastrium . Situated between the fundus of the stomach and the diaphragm. The spleen is very vascular and reddish purple in color ; A healthy spleen is not palpable.

4. History The spleen was thought to influence personality, mood and thought. Remove black bile from blood. Only in last 100 years its role in hematopoiesis , immunity is realised.

5. Embryology

6. Embryology The spleen develops in the cephalic part of dorsal mesogastrium (from its left layer) during the sixth week of intrauterine life). Starts with number of nodules that fuse and form a lobulated spleen. Notching of the superior border of the adult spleen is evidence of its multiple origin

7. Ends

8. Ends 2 ends - anterior and posterior end. The anterior end of the spleen is expanded and is more like a border; it is directed forward and downward to reach the midaxillary line. The posterior end is rounded and is directed upward and backward; it rests on the upper pole of the left kidney.

9. Size and Weight

10. Size and Weight 75-150 g 5-6cm x12-15cm Diagnostic imaging to assess  spleen size  is routinely accomplished by ultrasonographic measurement along its long axis. However, there is variation among radiological texts in defining the upper limits of  normal  for longitudinal diameter, with values ranging from 12 to 14 cm in adults.

11. Surfaces

12. Surfaces 2 surfaces- diaphragmatic and visceral. The diaphragmatic surface is smooth and convex, The visceral surface is irregular and concave and has impressions. Hilum is on the inferomedial part of the gastric impression . The hilum transmits the splenic vessels and nerves and provides attachment to the gastrosplenic and splenorenal ( lienorenal ) ligaments.

13. Relations

14. Relations The visceral surface of the spleen contacts the following organs: Anterior surface of the left Kidney. Splenic flexure of the colon The fundus of the stomach Tail of the Pancreas. The diaphragmatic surface is related to the diaphragm; the diaphragm separates the spleen from the pleura and the lung.

15. Visceral Surface:Impressions .

16. Borders

17. Borders 3 borders superior, inferior, intermediate. The superior border of the spleen is notched by the anterior end. The inferior border is rounded. The intermediate border directs toward the right.

18. Arterial Supply

19. Arterial Supply The splenic artery -the largest branch of the celiac trunk . Passing through the splenorenal ligament. It divides into multiple branches at the hilum . The spleen has superior and inferior vascular segments based on the blood supply. The 2 segments are separated by an avascular plane. Its terminal branches aside, the splenic artery also gives off branches to the pancreas, 5-7 short gastric branches, and the left gastro- omental ( gastroepiploic ) artery 

20. Splenic Artery

21. Venous Drainage The splenic vein

22. Venous Drainage The splenic vein Forms at the hilum . Runs behind the pancreas Joins Superior mesenteric vein behind the neck of the pancreas to form the portal vein. Tributaries- The short gastric left gastro- epiploiic Pancreatic Inferior mesenteric veins.

23. Venous Drainage

24. Lymphatic Drainage

25. Lymphatic Drainage Proper splenic tissue has no lymphatics ; however, some arise from the capsule and trabeculae and drain to the pancreaticosplenic lymph nodes.

26. Nerve supply

27. Nerve supply Sympathetic supply is from Celiac Plexus. There is no parasympatetic supply.

28. Peritoneal Attachments

29. Peritoneal Attachments The spleen is surrounded by peritoneum and is suspended by multiple ligaments:- The gastrosplenic ligament The splenorenal ligament The phrenicocolic ligament .

30. Peritoneal Attachments The gastrosplenic ligament extends from the hilum of the spleen to the greater curvature of the stomach; it contains short gastric vessels and associated lymphatics and sympathetic nerves. The splenorenal ligament extends from the hilum of the spleen to the anterior surface of the left kidney; it contains the tail of the pancreas and splenic vessels.

31. Peritoneal Attachments 3. The phrenicocolic ligament is a horizontal fold of peritoneum that extends from the splenic flexure of the colon to the diaphragm along the midaxillary line; it forms the upper end of the left paracolic gutter.

32. Surface Marking

33. Surface Marking The spleen is marked on the left side of the back with the long axis of the 10th rib. The upper border is marked along the upper border of the ninth rib; the lower border, along the 11th rib. The medial end lies 5 cm from the midline. The lateral extension ends at the midaxillary line.

34. Microscopic Anatomy

35. Microscopic Anatomy The spleen has4 components:- Supporting tissue White pulp Red pulp Vascular system

36. Microscopic Anatomy

37. Microscopic Anatomy Supporting tissue is fibroelastic and forms the capsule, coarse trabeculae , and a fine reticulum. The white pulp consists of lymphatic nodules, which are arranged around an eccentric arteriole called the Malpighian corpuscle.

38. Microscopic Anatomy 3. The red pulp is formed by a collection of cells in the interstices of the reticulum, in between the sinusoids. The cell population includes all types of lymphocytes, blood cells, and fixed and free macrophages. The lymphocytes are freely transformed into plasma cells, which can produce large amounts of antibodies and immunoglobulins

39. Microscopic Anatomy 4. The vascular system traverses the spleen and permeates it

40. Congenital Anomalies Accessory spleens or splenunculi -nodules that fail to fuse during development. Found in 18.8% In gastrosplenic ligament, splenorenal ligament, gastrophrenic ligament, and gastrocolic ligament. Rarely broad ligament of the uterus and in the spermatic cord. May grow if spleen is removed. Asplenia is a rare condition in which a congenital absence of the spleen occurs.

41. Physiology

42. Physiology Functions of Spleen Immune responses Phagocytosis Hematopoiesis Storage of red blood cells.

43. Hematopoiesis

44. Hematopoiesis The spleen is an important hematopoietic organ during fetal life. Lymphopoiesis continues throughout life. The manufactured lymphocytes take part in immune responses of the body. In the adult spleen, hematopoiesis can restart in certain diseases such as chronic myeloid leukemia and myelosclerosis .

45. Immune responses

46. Immune responses After antigenic stimulation increased formation of plasma cells for humoral responses increased lymphopoiesis for cellular responses occurs. It processes encapsulated bacteria Streptococcus pneumoniae , Haemophilus influenzae type B and Neisseria meningitidis types A and C. About 0.5 percent of people who have their spleens removed develop overwhelming post- splenectomy infection (OPSI)

47. Phagocytosis

48. Phagocytosis Spleen filters the blood Phagocytes in the spleen remove- debris old and effete red blood cells (RBCs) other blood cells Microorganisms Phagocytosis of circulating antigens initiates the humoral and cellular immune responses

49. Storage of RBCs

50. Storage of RBCs Approximately 8% of the circulating RBCs are present within the spleen; however, this function is seen better in animals than humans. As much as 25% of the circulating platelets are estimated to be held in reserve in the spleen

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