Anatomy of digestive sys stomach&si 2012

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Anatomy of digestive sys stomach&si 2012

  1. 1. ANATOMY OF DIGESTIVE SYSTEM: STOMACH & SMALL INTESTINE DR. HERMIZI HAPIDIN SCHOOL OF HEALTH SCIENCES HEALTH CAMPUS UNIVERSITI SAINS MALAYSIA hermizi@kck.usm.my hermizi@kck usm my 23th February 2012
  2. 2. OBJECTIVES At the end of this lecture, the students should understand : 1) Introduction to Lower Gastrointestinal (GI) Tract 2) Gross Anatomy of Stomach 3) Relations Blood Supply Lymphatic Drainage & Nerve Relations, Supply, Supply of Stomach 4) Gross Anatomy of Small Intestine 5) Bl d S Blood Supply, L l Lymphatic D i h i Drainage & N Nerve S Supply of l f Small Intestine
  3. 3. INTRODUCTION OF DIGESTIVE SYSTEM The organs involved in the g breakdown of food It has two anatomical subdivisions : a) Digestive tract b) Accessory organs
  4. 4. DIGESTIVE SYSTEM Digestive tract  Alimentary canal or gastrointestinal (GI) tract  A tube extending fromg mouth to anus (~ 9 meters long in cadaver)  It includes ; i. Upper GIT oral cavity, pharynx, esophagus ii. Lower GIT stomach, small intestine, large intestine (aliment = food)
  5. 5. DIGESTIVE SYSTEM Accessory organs y g  They include ; i. teeth ii. tongue t iii. salivary glands iv. liver v. gall bladder vi. pancreas * produce variety of secretions to contribute to breakdown of f d t ff b kd f foodstuffs
  6. 6. STOMACH Old names = grinding chamber, fermentation vat, cooking pot Dilated portion of alimentary canal between esophagus and small intestine (duodenum) i t ti (d d ) Site – it lies inferior to diaphragm in the epigastric, umbilical & left hypochondriac of the abdomen
  7. 7. Location of Stomach Midclavicular lines Midsternal line Subscostal line (10th costal cartilages) Umbilicus Transtubercular line (iliac tubercles) Subscostal lineAnterior view showing location of abdominopelvic regions Anterior view showing location of abdominopelvic regions
  8. 8. Functions of StomachStomacha) stores the food we ateb) breaks down the food into a liquidly mixturec) mix with enzymes which is chemical that breaks down foodd) slowly empty that liquidly mixture into the small intestine
  9. 9. STOMACHCapacity E Empty = 50 ml of f d t l f food After meals = 1.0 to 1.5 L Extremely full = up to 4 L y p T1Extension It extends between the level Cardiac/ esophageal of T11 & L1 vertebra f t b sphincter Upper end continues with esophagus through cardiac p g g sphincter Lower end continues with Pyloric L1 duodenum through pyloric sphincter sphincter
  10. 10. GROSS ANATOMY OF STOMACH Shape = pear shaped or “J” shaped (upper part is broader Cardiac end than lower part) It has two ends ; i. Cardic end ii. Pyloric end Lesser curvature It has two surfaces ; i. Anterior ii. ii Posterior Greater curvature It has two curvatures ; Pyloric end i. Lesser curvature ii. Greater curvature
  11. 11. GROSS ANATOMY OF STOMACHLesser curvature (LC) f forms right b d i ht border of stomach f t h (concave medial border) extends from cardiac orifice to pylorus l it is suspended from liver by lesser omentumGreater curvature (GC) forms longer convex lateral border of stomach gastrosplenic omentum extends from upper part of GC to spleen greater omentum extends from g lower part of GC to transverse colon (Omentum = fat skin)
  12. 12. GROSS ANATOMY OF STOMACH Stomach is covered byperitoneum (intraperitonealorgan) Peritoneum leaves lessercurvature as lesser lomentum & greatercurvature as greateromentum Peritoneum = serousmembrane that linesabdominal cavity & coversviscera within it Omentum = a fold ofpperitoneum
  13. 13. Greater omentum is Lesser omentum Mesentery of smallshown in its normal attaching liver to intestine position covering lesser curvature ofmost of abdominal stomach viscera
  14. 14. Greater Omentum Falciform ligament Liver Gallbladder Spleen Stomach Ligamentum teres Greater omentum (anterior to SI) Small intestine Cecum
  15. 15. Lesser OmentumLiverGallbladderLesser omentum(extend from liver to LC)StomachDuodenumTransverse colonSmall intestineCecumUrinary bladder
  16. 16. Parts of StomachStomach has four parts :a) Cardiab) Fundusc) Body Fundus Cardia C did) Pylorus Cardia – surrounds superior Body opening of stomach Fundus – dilated upper part Pylorus Body – inferior to fundus, located between cardiac & pyloric ends Pylorus y – funnel-shaped p region of stomach
  17. 17. Parts of Stomach The pylorus (“gate keeper”) has two parts : i. Pyloric antrum ii. Pyloric canal Pyloric antrum (antrum = cave) – proximal dilated portion that connects to the body of stomach Pyloric canal – narrow portion Pyloric orifice Pyloric Pyloric which leads into duodenum Pyloric canal antrum t Pyloric sphincter - thickened sphincter distal end of the canal
  18. 18. Anterior Surface of Stomach Esophagus Fundus Cardia Longitudinal muscle layer Circular muscle layer Lesser L Body B d Pyloric sphincter curvature LeftDuodenum gastroepiploic vessels Oblique muscle l Obli l layer Greater curvature Pylorus y Rugae
  19. 19. Relations of StomachAnteriorly Posteriorly Abd Abdominal wall i l ll  Di h Diaphragm Left costal margin  Spleen Left pleura & lung  Left suprarenal gland Diaphragm  Upper part of left kidney Left lobe o liver e t obe of e  Splenic a te y Sp e c artery  Pancreas  Transverse mesocolon  Transverse colon
  20. 20. Stomach Bed Structures related to posteroinferior surface of stomach From superior to inferior, it is formed by :  Left dome of diaphragm  Spleen Spleen  Left suprarenal gland Diaphragm Left suprarenal & left kidney  Left kidney y Pancreas & Splenic artery Splenic artery Transverse colon  & mesacolon  Pancreas (head, neck & body)  Transverse mesocolon T l  Transverse colon  Spleen separated from stomach by greater sac of peritoneum while Sp ee sepa a ed o s o ac g ea e o pe o eu e other structures by lesser sac
  21. 21. Stomach Spleen Diaphragm Pancreas & Splenic arteryTransverse colon & mesacolon Fig. Posterior relations of stomach greater sac = main part of peritoneal cavity lesser sac / omental bursa = lies posterior to stomach Fig. Sagittal section
  22. 22. Stomach Epiploic foramen/omental foramen/foramen of Winslow Fig. Horizontal sections through abdomen Greater sac or general cavity (red) and lesser sac / omental bursa (blue) Lesser sac is embryologically formed from an infolding of greater omentum
  23. 23. Histology of Stomach Stomach wall is composed of four basic layers (inside to outside) : a) Mucosa layer b) Submucosa c) Muscular layer d) Serous llayer
  24. 24. Histology of Stomach Mucosa layer  Layer of simple columnar epithelium  Contains lamina propria (areolar CT) & muscularis mucosae (s oot (smooth muscle) usc e) Submucosa layer  Lie deep to mucosa layer  Composed of areolar CT Muscularis layer  Has 3 layers of smooth muscle ; outer longitudinal layer, middle circular l i l layer & i inner oblique l bli layer Serous layer  Composed of simple squamous epithelium (mesothelium) & areolar CT
  25. 25. Layers of Stomach Wall Serous layer Muscularis layer Mucosa layer Submucosa layer RUGAE (Folds in mucosa layer)
  26. 26. Layers of the stomach wall Surface epithelium Mucosa Lamina propria Muscularis mucosaeSubmucosa(contains submucosalplexus) Oblique layer q yMuscularis externa Circular layer(contains myenteric Longitudinalplexus) layerSerosa Stomach wall
  27. 27. Enlarged view of gastric pits and gastric glands – Mucosa layer Gastric pits Surface epithelium ( (mucous cells)) Gastric pit Mucous M co s neck cells*Gastric pits lead Parietal cellinto gastric glands Chief cell Gastric gland Enteroendocrine cell
  28. 28. Gastric Gland Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Mucous neck cell Cell types Parietal cell  Mucous neck cells (secrete thin thin, acidic mucus)  Parietal cells  Chief cells Chief cell  Enteroendocrine or G cells G cell Gastric gland
  29. 29. Interior of Stomach Rugae • numerous gastric folds • mainly in longitudinal direction • f ld flatten out when stomach is distended folds fl tt t h t h i di t d d
  30. 30. Arterial Supply of Stomach Arterial supply to stomach is extremely rich & comprises of : a) Left gastric artery - coeliac axis b) Right gastric artery - hepatic artery c) ) Right gastroepiploic artery - gastroduodenal branch (hepatic artery) g g pp y g ( p y) d) Left gastroepiploic artery - splenic artery e) Short gastric arteries - splenic artery Left gastric artery COELIAC AXIS Shorts gastric arteries Cystic artery HEPATIC ARTERY SPLENIC ARTERY Right gastric artery GASTRODUODENAL ARTERY Left gastroepiploic artery Superior pancreatiduodenal artery Right gastroepiploic artery
  31. 31. Venous Drainage (Stomach) Gastric veins parallel the arteries in possition and course : a) Left gastric vein b) Right gastric vein drain into portal vein c) ) Right gastroepiploic vein - empties in superior mesenteric vein g g pp p p d) Left gatroepiploic vein drain into splenic vein e) Short gastric veins
  32. 32. Lymph Drainage (Stomach) Lymphatic drainage of stomach accompanies its blood vessels Stomach can be divided into three drainage zones : a) Area I - drains along right & left gastric vessels to aortic nodes b) Area II - drains along right epiploic vessels to subpyloric nodes & thence to ) g g pp py aortic nodes c) Area III - drains via lymphatics along splenic vessels to suprapancreatic nodes & thence to aortic nodes Lymph drainage of stomach
  33. 33. Nerve Supply of Stomach Sympathetic nerve supply of the stomach from T5 through T9 segments of spinal cord passes to celiac plexus via greater splanchnic nerve l h i Parasympathetic nerve supply the stomach is from anterior and posterior vagal t k & d t i l trunk their branches • anterior vagal trunk derived mainly from mainl f om left vagus ne e ag s nerve • posterior vagal trunk derived mainly from right vagus nerve
  34. 34. Small Intestine Stomach Duodenum D d Duodenojejunal flexureJejunumAscendingcolonMesenteryIleocecaljunctionj tiCecumAppendixIleum
  35. 35. SMALL INTESTINE Is the longest part of alimentary canal li t l Extends from pylorus of stomach to ileocecal junction j Length = 3 m in a living person & 6.5 m in a cadaver (loss of muscle tone) Diameter = 4 cm in stomach Small intestine & 2.5 cm at junction with large intestine Function = digestion of food and absorption of nutrients
  36. 36. Location of Small Intestine Site = it occupies all abdominal regions except epigastic and hypochondriac region Fixation = it is stabilized by mesentery Mesentery = peritoneal fold attaching small intestine to posterior body wall Sagittal section
  37. 37. Mesentery of Small Intestine 25- 37 Greater omentum (retracted) Transverse colon Mesocolon Descending colon Mesentery Jejunum Sigmoid colonMesentery of small intestines holds many blood vessels
  38. 38. Gross Anatomy of Small Intestine Anatomical subdivisions : a) Duodenum b) Jejunum c) Ileum Duodenum = C-shaped tube which is attached to the stomach t h Jejunum = is the coiled midsection Ileum = the final section, which leads into the large intestine
  39. 39. Small Intestine – Duodenum C-shaped tube about 25 cm long & width 3 75 cm 3.75 Joins stomach to jejunum The first & shortest part of p small intestine The widest & most fixed part Curves around the head of pancreas Begins at pylorus on right side & ends at duodenojejunal junction on Duodenum left side Partially retroperitoneal
  40. 40. Small Intestine - Parts of Duodenum Duodenum is divided into four parts : a) First (superior) part b) Second (descending) part 1st part c) Third (horizontal) part d) Forth (ascending) part First part of duodenum 2nd part 4th part  It is 5 cm long 3rd part  Lies anterolateral to the body of L1 vertebra
  41. 41. Small Intestine - Parts of Duodenum Second part of duodenum  It i 7 t 10 cm l is to long  Descends along right sides of L1 through L3 vertebrae Third part of duodenum 1st part  It is 6 to 8 cm long  Crosses L3 vertebra 2nd part Forth part of duodenum 4th part  It is 5 cm long 3rd part Jejunum J j  Begins at left of L3 vertebra & rises superiorly as far as superior border of L2 vertebra and continues with jejunum
  42. 42. Interior of Duodenum(flexure at junction offirst and secondparts of duodenum) Superior duodenal flexure 1st part (superior) – ampulla (no circular folds) 2nd part (descending) Minor duodenal papilla Duodenojejunal flexure Valves of Kerckring Jejunum (circular folds) Major duodenal palilla (of Vater) Longitudinal fold 4th part (ascending) Head of pancreas 3rd part (horizontal) Superior mesenteric artery and vein
  43. 43. Interior of Duodenum Plicae circulares2nd part ofduodenum Major duodenal papilla Note smooth muscle lining of 1st part of duodenum, plicae circularis(circular folds) of 2nd part of duodenum Major duodenal papilla is a small rounded elevation at site where bileduct & main pancreatic duct pierce medial wall of 2nd part of duodenum
  44. 44. Small Intestine – Jejunum & Ileum Jejunum begins at duodenojejunal fl d d j j l flexure (L2) & Pylorus of ileum ends at ileocecal stomach Duodenum junction Ascending colon Jejunum & ileum = 6 to 7 m Mesentery long (jejunum 2/5, ileum 3/5) Jejunum Coils of jejunum & ileum are suspended by mesentery from posterior abdominal wall & freely movable Ileocecal Il l Jejunum J j junction Most jejunum lies in left Cecum Ileum upper quadrant & most ileum lies in i ht lower quadrant li i right l d t
  45. 45. Differences between Jejunum & Ileum Characteristic Jejunum IleumColor Deeper red Paler pinkWall Thick & heavy Thin & lightVascularity Greater LessArcades A few large loops Many short loopsVasa recta /V t Long L Short Sh tarteriae rectaeFat in mesentery Less MoreCircular folds Large, tall & closely packed Low & sparse; absent in(plicae circularis) (valves of Kerkring) distal partLymphoid nodules Few y p o d odu es ew Many a y(Peyer’s patches)
  46. 46. JEJUNUM JEJUNUM MesenteryArcade of jejunal arteriesStraight arteries(arteriae rectae) SerosaLongitudinalmuscle layer Circular Ci lmuscle layer Barium radiograph of jejunumSubmucosa Mucosa Circular folds (valves of Kerckring) Solitary lymphoid nodule
  47. 47. ILEUM ILEUM Mesentery Arcade of ileal arteries Straight arteries (arteriae rectae) Se osa ( sce a Serosa (visceral peritoneum)Longitudinalmuscle layer Circular Ci lmuscle layer Barium radiograph of ileumSubmucosa Mucosa Circular folds Solitary lymphoid nodules Aggregate lymphoid nodules (Peyer’s patches)
  48. 48. The main distinguishing featureof the jejunum is the presence of prominent Valves of Kerckring (plicae circulares) -numerous folds of the mucous Barium radiograph of jejunum membrane of the small intestine. The ileum is almost devoid of Valves of Kerckring, but g large accumulations of lymphatic tissue or Peyers Patches. Barium radiograph of ileum Peyer’s patches
  49. 49. External and internal differences between jejunum and ileum Thick wall Jejunum Jejunum Plicae circularis (valves of Kerckring) Fat Thin wall Arterial arcades Ileum Superior mesenteric artery Fat Ileum Peyer’s patch Smooth mucous membrane Arterial arcades Superior mesenteric artery
  50. 50. Ileocecal Junction Point where smallintestine (ileum) ends ( ) as it opens into large intestine (cecum) ; occurs usually within the iliac fossa (right ( g lower quadrant of abdomen) Iliac fossa
  51. 51. Histology of Small Intestine Wall of small intestine is made of the following layers : a) Serosa coat b) Muscular coat c) ) Submucosa coat d) Mucosa coat Serosa – made of peritoneum Muscular – made of smooth muscle fibers arranged in outer longitudinal & inner circular layers Submucosa – contains loose CT & large venous plexuses (submucosa duodenum contains duodenal or Brunner’s glands) Brunner s Mucosa – composed of a layer of epithelium, lamina propria & muscularis mucosa (Plicae circulares numerous in jejunum, Peyer’s patches present in ileum)
  52. 52. Histology of Small IntestineVilli (tufts of hair) = fingerlike projections of mucosa (0.5 – 1mm long) Layers of small intestine
  53. 53. Histology of Small Intestine * One mucous tubule is outlined in the image above.Brunners glands are compound, tubular, mucous glands in the submucosa of the duodenum.
  54. 54. Histology of Small Intestine Villi (Small, finger-like projections of mucosa)
  55. 55. Histology of Small Intestine Ileum Mucosa SubmucosaPlicae circulares - jejunum Payer’s patch in ileum mucosa
  56. 56. Intestinal crypt = crypt of Lieberkuhn Microvilli (brush border)Absorptive cellsLactealGoblet cellBlood ViluscapillariesMucosaassociatedlymphoid tissue EnteroendocrineIntestinal crypt cellsMuscularis Venulemucosae Lymphatic vesselDuodenal gland Submucosa
  57. 57. Intestinal Crypts Intestinal crypt epithelium i l i h li  Secretory cells that produce intestinal juice  Enteroendocrine cells  Intraepithelial lymphocytes (IELs)  Release cytokines that kill infected cells  Paneth cells  Secrete antimicrobial agents (defensins and lysozyme)  Stem cells
  58. 58. Blood Supply of Small IntestineDuodenumArterial supply i l l Upper half is supplied by Portal vein superior pancreaticoduodenal Superior mesenteric vein artery (gastroduodenal artery) Superior panncreaticoduodenal artery Lower half is supplied by inferior pancreaticoduodenal p artery (superior mesenteric Inferior panncreaticoduodenal artery) arteryVenous drainage Superior pancreaticoduodenal vein drains into portal vein (inferior vein joins superior mesenteric vein)
  59. 59. Arterial Supply of Duodenum Gastroduodenal artery Superior pancreaticoduodenal arteryPosterior superior pancreaticoduodenal artery Anterior superior pancreaticoduodenal artery Inferior pancreaticoduodenal artery Posterior inferior pancreaticoduodenal artery SUPERIOR MESENTERIC ARTERY Anterior inferior pancreaticoduodenal artery
  60. 60. Blood Supply of Small IntestineIleum and Jejunum Arterial supply  From branches of superior mesenteric artery  Intestinal branches arise from left side of the artery & run in mesentery to reach the gut (gastrointestinal tract)  They anastomose with one another to form as series of arcades  Lowest part of il L t t f ileum i supplied b il is li d by ileocolic artery li t Venous drainage  Veins correspond to branches of superior mesenteric artery & drain into superior mesentery vein
  61. 61. Arterial Supply & Venous Drainage of Small Intestine
  62. 62. Superior mesenteric artery and its branches
  63. 63. Lymphatic Drainage of Small IntestineDuodenum Lymph vessels follows arteries & drain ;  upward via pancreaticoduodenal nodes to gastroduodenal nodes & then to celiac nodes  downward via pancreaticoduodenal nodes to superior mesenteric nodes around origin of superior mesentery arteryJejunum & Ileum Lymph vessels pass through many intermediate mesenteric nodes & finally reach superior mesenteric nodes (situated around origin of mesenteric artery)
  64. 64. Celiac nodesSuperior mesenteric nodes (central superior group) Superior mesenteric S i t i nodes (juxtaintestinal group) mesenteric lymph nodes located in immediate proximity to the jejunum or ileum
  65. 65. Nerve Supply of Small IntestineDuodenum Nerves are derived from sympathetic & parasympathetic (vagus) nerves from celiac & superior mesenteric plexusesJejunum & Ileum Nerves are derived from sympathetic & parasympathetic (vagus) nerves from superior mesenteric plexus
  66. 66. Practical Session 0n 05/03/2012(MONDAY): Digestive system II TIME GROUP A 2.00 3 30 p.m. 2 00 to 3.30 p m B 3.30 to 5 00 3 30 t 5.00 p.m.

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