Anatomy of spleen

Brief Anatomy of Spleen

1. Good morning

2. Anatomy of Spleen Chris Saji MBBS 2015

3. DEVELOPMENT OF SPLEEN Spleen develops in the cephalic part of the dorsal mesogastrium from its left layer during 6 th week of Intra-uterine life into a number of nodule which soon fuse to form a lobulated spleen. Notching of Superior border is an evidence of its multiple origin

4. Congenital Anomaly Nodules which fail to fuse form accessory spleen or spleniculi , these may be present at the a) Hilum of Spleen ( the most common site ) b) Tail of pancrease c) Derivatives of Dorsal mesogastrium : Greater Omentum , Gastrophrenic ligament , gastrosplenic ligament , linorenal ligament. d) Broad ligament of uterus e) Spermatic cord f) Asplenia

5. Spleen Anatomy : Location Spleen is the largest lymphoid organ of the body. It is situated in the Upper left part of the abdomen between the fundus of stomach and diaphragm. It lies mainly in the left hypochondrium ( lateral 2/3 ) and partly in the epigastrium (medial 1/3 )

6. Size And Measurements Average Spleen is 12.5 cm long , 7.5 cm broad and 2.5 cm thick . Weight : 75 – 150 g A healthy spleen is not palpable

7. Relation to Ribs It is related to 9 th to 11 th ribs on the left side. The Spleen lies obliquely along the long axis of 10 th rib . Thus it is directed downwards , forwards and laterally , making an angle of about 45 degree with horizontal plane.

8. Gross Morphology Spleen presents a hilum , 2 ends / poles , 3 margins , 2 surface

9. Surface Marking The outline of the spleen is drawn on the back of the thoracic wall on the left side. A ) The medial end of the spleen is represented by a point about 4-5 cm away from midline at the level of the spine of 10 th thoracic vertebrae , thus the superior and inferior margin begins from this point.

10. B) lateral end of the spleen is represented by a point on the 10 th rib on the mid-axillary line . The superior and Inferior margin converge at this point.

11. 4-5cm

12. The Upper margin of spleen corresponds to upper border of the 9 th rib The lower margin of the spleen corresponds to lower margin of the 11 th rib

13. Peritoneal Relation

14. Peritoneal Relations Spleen is completely covered by the peritoneum . It gives attachments to 2 peritoneal ligaments and rest on 1 peritoneal ligament. 1) Linorenal ligament : Connects the spleen to the posterior abdominal wall and contains the splenic vessels , tail of pancrease , pancreatico-splenic lymph nodes , lymphatics & Sympathetic nerves .

15. 2) Gastro-splenic ligament : Connects spleen to greater curvature of stomach and contains left gastro- epiploic and short gastric vessels, associated lymphatics & s ympathetic trunk.

16. 3 ) Phrenico-colic Ligament ( Sustentaculum Lienei ) It is not attached to spleen but supports its anterior end and prevents its downward displacement in splenomegaly , so the spleen tends to extend downwards and medially towards right iliac fossa ( and not in left iliac fossa)

17. 3) Phrenico-colic Ligament ( Sustentaculum Lienei )

18. Blood Supply Arterial supply : It is through the highly tortuous splenic artery , which is the largest branch of the celiac trunk , Enters through the hilum of spleen

19. Branches to Pancreas : Multiple branches serving the pancreas. The largest is the arteria pancreatica magna . Short gastric artery : Supplies the upper part of greater curvature of stomach and fundus of stomach. Left gastroepiploic artery : middle portion of greater curvature of stomach. Other Branches to Splenic Artery

20. Venous Drainage : Through the splenic vein which unites with the superior mesenteric vein to form portal vein behind the neck of pancrease.

21. Nerve Supply : It is through the coeliac plexus which is the sympathetic supply of spleen. It innervates splenic arterial branches

22. Lymphatic Drainage : Spleen filters blood and not lymph , it receives no afferent lymphatic vessels . However , efferent vessels from stroma and capsule terminate in pancreatico-splenic lymph node . Note : Cancer Cells rarely spread to the spleen because it lacks afferent lymph vessels and its microenvironment does not favour implantation and growth of malignant cells .

23. Splenic Parenchyma

24. Structure of Splenic Parenchyma Spleen comprises of many units of red pulp and white pulp , which are centred around central arterioles . White Pulp :1) Aggregations of T and B Lymphocytes around arterioles form white pulp / Malpighian bodies .

25. 2) Arrangements of lymphoid tissue around the arteriole of each white pulp are as follows. a) T-cells are arranged around the arteriole and is called Periarteriolar Lymphatic Sheath ( PALS ). b) B-cells in middle. c) Dendritic cells at periphery.

26. 3) Red Pulp : Composed of Splenic Cords of Billroth separated by venous sinusoids . a) Venous sinusoids drain into tributaries of splenic vein b) Venous sinusoids are lined by endothelial stave cells which form incomplete layer and present intracellular slits between them through which blood can percolate.

27. Thank you