Duodenum.pptx...........................

anatomy of duodenum

1. DUODENUM

2. INTRODUCTION First, Shortest, widest, and most fixed part of small intestine Do- deka - dactulos -12 fingers breadth Length = combined width of 12 fingers Mostly retroperitoneal (except 1 st part) C shaped, encloses the head of the pancreas Location :- epigastric and umbilical region

3. Subdivided into four parts First or upper part –2inches/ 5cm Second or vertical part –3inches/ 7.5cm Third or horizontal part –4inches/10cm Fourth or ascending part – 1inch/ 2.5cm

4. First part of duodenum Extension –pylorus to superior duodenal flexure Direction –upwards, backwards and to the right Length -5cm or 2inches Features - Most movable, partly retroperitoneal - Develops from foregut Supplied by end arteries Devoid of circular mucous fold

5. Relations : Anteriorly – covered with peritoneum of the greater sac, and is related to Quadrate lobe of liver Neck and body of gall bladder Posteriorly –non-peritoneal related to Portal vein, Bile duct, Gastroduodenal artery, IVC

6. Relations Superiorly – forms floor of epiploic foramen and related to hepatic artery Inferiorly –head and neck of pancreas

7. Second part of duodenum Extension –from superior duodenal flexure to inferior duodenal flexure Upper ½ develops from foregut & lower ½ from midgut . Direction –downward in front of hilum of kidney Length – 3inches or 7.5cm

8. Relations : Anteriorly – Rt lobe of liver Fundus and body of gall bladder Transverse colon

9. Posteriorly – Rt kidney, Rt renal vessels, pelvis of Rt ureter Rt psoas major muscle Rt edge of IVC

10. Laterally – Rt colic flexure Medially- Head of pancreas Anastomosis of Superior and inferior pancreatico -duodenal vessels Bile duct and pancreatic duct –unite to form ampulla of Vater

11. Interior of second part of duodenum Circular folds ( plicae circularis ) – permanent mucous folds Major duodenal papilla –conical projection arising from posteromedial wall, situated 8-10cm distal to pylorus Minor duodenal papilla –small conical projection situated 2cm above, opening of accessory pancreatic duct

12. Interior of second part of duodenum Plica semicircularis –forms an arch over Major duodenal papilla, resemble monk’s hood Plica longitudinalis –vertical fold extending from major papilla

13. Third part of duodenum Extension –from inferior duodenal flexure to front of aorta Length – 4 inches or 10 cm

14. Relations : Anteriorly –crossed by superior mesenteric vessels, root of mesentery Posteriorly –non-peritoneal and related to Rt psoas major, Rt ureter, IVC, Rt gonadal vessels, abdominal aorta

15. Relations Superiorly –head of pancreas, inferior pancreaticoduodenal vessels Inferiorly –coils of jejunum

16. Fourth part of duodenum Extension –from front of aorta to DJ flexure Length –1 inch or 2.5cm Flexure is kept in position by suspensory muscle of duodenum

17. Relations : Anteriorly –covered with peritoneum, related to transverse colon and mesocolon Posteriorly –Lt crus of diaphragm, Lt psoas major, Lt sympathetic trunk, Lt gonadal vessels, Lt suprarenal vein, inferior mesenteric vein Rt side – uncinate process Lt side –Lt kidney, ureter Above –body of pancreas

18. Suspensory muscle of duodenum OR Suspensory ligament of treitz Fibro-muscular band arises from Rt crus of diaphragm Passes downward and forward by side of coeliac artery The band is attached to posterior surface of DJ flexure Upper 1/3 –striated muscle middle 1/3 –elastic fibres lower 1/3 – nonstriated muscle

19. Function –flexes Dj flexure and prevent it from being dragged down - Landmark in radiological diagnosis of incomplete rotation or mal rotation of small intestine

20. Structure of duodenum Serosa –derived from peritoneum, incomplete Muscularis externa –outer longitudinal, inner circular separated by myenteric plexus of nerves Submucosa –loose areolar tissue contain plexus of blood vessels, lymphatics , meissner’s plexus, Brunner’s gland Mucosa –surface epithelium, lamina propria , muscularis mucosa

21. ENDOSCOPIC APPEARANCE 1 ST part 2 nd part Major duodenal papilla 3 rd part

22. Blood supply of duodenum Superior pancreaticoduodenal artery Inferior pancreaticoduodenal artery Supraduodenal artery of Wilkie  br of Gastroduodenal art Retroduodenal branch of gastroduodenal artery Leash of branches of hepatic artery Branches from Rt gastroepiploic artery Artery from first jejunal branch of SMA

23. Venous drainage Veins corresponding to arteries drain into SMV and portal vein

24. Lymphatic drainage Pancreaticoduodenal lymph nodes coeliac and superior mesenteric groups of pre-aortic lymph nodes

25. Nerve supply Sympathetic – from T6-T9 Parasympathetic –from both vagi through celiac and superior mesenteric plexus

26. Applied First part of duodenum –prone to peptic ulcer , supplied by series of end arteries Mucosal folds are absent Acidic contents of stomach enters Causes –trauma, alcohol, smoking, ulcerogenic drugs (NSAID) Sometimes gastroduodenal artery passing behind first part and get erroded by peptic ulcer, producing severe haemorrhage

27. Duodenal cap Devoid of circular folds in the 1 st part of duodenum seen as duodenal cap in barium meal radiographs of abdomen Presents a triangular shadow having a well demarcated base and less distinct apex  duodenal cap/ bulb.

28. Second part –more protected, opening of bile duct and pancreatic duct Small bile stones impacted on summit of major duodenal papilla – obstructive jaundice Annular type of head of pancreas –encircles the duodenum – malignant growth of pancreatic head – duodenal obstruction

29. Third part of duodenum – more prone to external injury as it may compressed between vertebral column & AAW following violence.

30. Duodenal recess Superior –bounded in front by superior duodenal fold Inferior –bounded in front by inferior duodenal fold Retroduodenal –behind junction of 3 rd and 4 th part Paraduodenal –anteriorly bounded by paraduodenal fold contain inferior mesenteric vein

31. A loop of small gut may herniate into any of the recess If the gut fails to return, the internal hernia thus formed produces intestinal obstruction