Stomach

It includes structure of stomach, stomach bed, function and internal structure.
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The stomach is an important organ and the most dilated portion of the digestive system. The esophagus precedes it, and the small intestine follows. It is a large, muscular, and hollow organ allowing for a capacity to hold food. It is comprised of 4 main regions, the cardia, fundus, body, and pylorus.

1. STOMACH MR. ABHIJIT P. BHOYAR ASST. PROFESSOR CHILD HEALTH NURSING

2. introduction The stomach is also called the gaster (Greek belly) or venter from which we have the adjective gastric applied to structures related to the organ. The stomach is an important organ and the most dilated portion of the digestive system.

3. Definition The stomach is a muscular bag forming the widest and most distensible part of the digestive tube. It is connected above to the lower end of the oesophagus , and below to the duodenum. It acts as a reservoir of food and helps in digestion of carbohydrates, proteins and fats.

4. Location The stomach lies obliquely in the upper and left part of the abdomen, occupying the epigastric , umbilical and left hypochondriac regions . Most of it lies under cover of the left costal margin and the ribs.

5. Shape of stomach The shape of the stomach depends upon the degree of tone of its muscles and tone of muscles of the body. In normal active persons ( sthenic ), its shape is somewhat J-shaped In thin, tall persons ( hyposthenic ), its shape is J-shaped, while in broad, strong and very active persons, its shape is horizontal. The shape of the stomach can be studied in the living by radiographic examination after giving a barium meal

6. Size and Capacity The stomach is a very distensible organ . It is about 25 cm long , and the mean capacity is one ounce (30 ml) at birth, one litre (1000 ml) at puberty, and 1½ to 2 litres or more in adults.

7. EXTERNAL FEATURES The stomach has two orifices or openings , two curvatures or borders, two surfaces and two parts .

8. Two Orifices THE CARDIAC ORIFICE is joined by the lower end of the oesophagus . It lies behind the left 7th costal cartilage 2.5 cm from its junction with the sternum, at the level of vertebra T11.

9. 2) THE PYLORIC ORIFICE opens into the duodenum. In an empty stomach and in the supine position, it lies 1.2 cm to the right of median plane, at the level of lower border of vertebra L1 or transpyloric plane. Its position is indicated on the surface of the stomach: a. By a circular groove (pyloric constriction produced by the underlying pyloric sphincter or pylorus; pylorus = gate guard) which feels like a large firm nodule. b. By the prepyloric vein which lies in front of the constriction.

10. Two Curvatures

11. Two Surfaces

12. Two Parts The stomach is divided into two parts—cardiac and pyloric. By a line drawn downwards and to the left from the cardiac end to the angular notch (lowest point of lesser curvature ). The line is extended further to the greater curvature . The larger cardiac part is further subdivided into fundus and body. The smaller pyloric part is subdivided into pyloric antrum and pyloric canal

13. Cardiac Part 1. The fundus of the stomach is the upper convex dome shaped part situated above a horizontal line drawn at the level of the cardiac orifice. It is commonly distended with gas which is seen clearly in radiographic examination under the left dome of the diaphragm 2. The body of the stomach lies between the fundus and the pyloric antrum .

14. It can be distended enormously along the greater curvature. The gastric glands, distributed in the fundus and body of stomach, contain all three types of secretory cells, namely: a. The mucous cells. b. The chief, peptic or zymogenic cells which secrete the digestive enzymes. c. The parietal or oxyntic cells which secrete HCl .

15. Pyloric Part 1. The pyloric antrum is separated from the pyloric canal by an inconstant sulcus, sulcus intermedius present on the greater curvature. It is about 7.5 cm long. The pyloric glands are richest in mucous cells. 2. The pyloric canal is about 2.5 cm long. It is narrow and tubular. At its right end, it terminates at the pylorus .

16. RELATIONS OF STOMACH Peritoneal Relations The stomach is lined by peritoneum on both its surfaces . At the lesser curvature, the layers of peritoneum lining the anterior and posterior surfaces meet and become continuous with the lesser omentum Along the greater part of the greater curvature, the two layers meet to form the greater omentum .

17. Near the fundus, the two layers meet to form the gastrosplenic ligament. Near the cardiac end, the peritoneum on the posterior surface is reflected onto the diaphragm as the gastrophrenic ligament The greater and lesser curvatures along the peritoneal reflections are also bare .

18. Visceral Relations The anterior surface of the stomach is related to the liver , the diaphragm, and the anterior abdominal wall. The diaphragm separates the stomach from the left pleura, the pericardium, and the sixth to ninth ribs. The space between left costal margin and lower edge of left lung on stomach is known as Traube’s space .

19. The costal cartilages are separated from the stomach by the transversus abdominis . Gastric nerves and vessels ramify deep to the peritoneum . Normally, on percussion, there is resonant note over this space; but in splenomegaly or pleural effusion, a dull note is felt at this site.

20. The posterior surface of the stomach is related to structures forming the stomach bed , all of which are separated from the stomach by the cavity of the lesser sac. These structures are: a. Diaphragm b . Left kidney c. Left suprarenal gland d . Pancreas e . Transverse mesocolon f . Splenic flexure of the colon g. Splenic artery

21. STOMACH BED

22. Sometimes the spleen is also included in the stomach bed, but it is separated from the stomach by the cavity of the greater sac (and not of the lesser sac). Gastric nerves and vessels ramify deep to the peritoneum.

23. ARTERIAL SUPPLY OF STOMACH The stomach is supplied along: i . The lesser curvature by: The left gastric artery, a branch of the coeliac trunk and the right gastric artery , a branch of the proper hepatic artery. ii. The greater curvature: It is supplied by the right gastroepiploic artery , a branch of the gastro-duodenal and the left gastroepiploic artery , a branch of the splenic artery. iii. Fundus is supplied by 5 to 7 short gastric arteries, which are also branches of the splenic artery

24. VENOUS SUPPLY OF STOMACH The veins of the stomach drain into the portal, superior mesenteric and splenic veins. Right and left gastric veins drain in the portal vein. Right gastroepiploic vein ends in superior mesenteric vein ; while left gastroepiploic and short gastric veins terminate in splenic vein

25. LYMPHATIC DRAINAGE

26. NERVE SUPPLY

27. INTERIOR OF STOMACH FEATURES 1. The mucosa of an empty stomach is thrown into folds termed as gastric rugae . The rugae are longitudinal along the lesser curvature and may be irregular elsewhere . The rugae are flattened in a distended stomach . On the mucosal surface, there are numerous small depressions that can be seen with a hand lens. These are the gastric pits. The gastric glands open into these pits.

28. The part of the lumen of the stomach that lies along the lesser curvature, and has longitudinal rugae , is called the gastric canal or magenstrasse. This canal allows rapid passage of swallowed liquids along the lesser curvature directly to the lower part before it spreads to the other part of stomach. Thus lesser curvature bears maximum insult of the swallowed liquids, which makes it vulnerable to peptic ulcer. So , beware of your drinks

29. 2 Submucous coat is made of connective tissue, arterioles and nerve plexus. 3 Muscle coat is arranged as under: a. Longitudinal fibres are most superficial, mainly along the curvatures. b. Inner circular fibres encircle the body and are thickened at pylorus to form pyloric sphincter c . The deepest layer consists of oblique fibres which loop over the cardiac notch.

30. Some fibres spread in the fundus and body of stomach. Rest form a well-developed ridge on each side of the lesser curvature . These fibres on contraction form ‘gastric canal’ for the passage of fluids. 4. Serous coat consists of the peritoneal covering.

31. FUNCTIONS OF STOMACH

32. CLINICAL ANATOMY Gastric pain is felt in the epigastrium because the stomach is supplied from segments T6 to T9 of the spinal cord, which also supply the upper part of the abdominal wall. Pain is produced either by spasm of muscle, or by over-distension . Ulcer pain is attributed to local spasm due to irritation

33. Peptic ulcer can occur in the sites of pepsin and hydrochloric acid, namely the stomach, first part of duodenum , lower end of oesophagus and Meckel’s diverticulum . It is common in blood group ‘O’. Gastric ulcer occurs typically along the lesser curvature. This is possibly due to the following peculiarities of lesser curvature.

34. Gastric ulcers are common in people who are always in ‘hurry’, mostly ‘worry’ about incidents and eat ‘spicy curry’. Gastric ulcer is notoriously resistant to healing and persists for years together, causing great degree of morbidity. To promote healing, the irritating effect of HCl can be minimised by antacids, partial gastrectomy or vagotomy . Gastric carcinoma is common and occurs along the greater curvature. On this account, the lymphatic drainage of stomach assumes importance .

35. Metastasis can occur through the thoracic duct to the left supraclavicular lymph node ( Troisier’s sign). These lymph nodes are called ‘signal nodes’. It is common in blood group ‘A’. Pyloric obstruction can be congenital or acquired. It causes visible peristalsis in the epigastrium and vomiting after meals (thin and long). Hyposthenic stomach is (long and narrow) more prone for gastric ulcer, while hypersthenic stomach is prone for duodenal ulcer (short and broad).

36. QUESTIONS ASK 1. Describe stomach under following headings. a. Position b. Gross features c. Peritoneal and visceral relations d. Blood supply and lymphatic drainage e. Clinical anatomy 2. Write short notes on: a. Abdominal part of oesophagus b. Portocaval anastomosis at lower end of oesophagus c. Stomach bed

37. MULTIPLE CHOICE QUESTIONS 1. Following structures form part of the stomach bed, except : a. Left suprarenal gland b. Coeliac trunk c. Splenic artery d. Pancreas 2. Which of the following is not present in the bed of stomach ? a. Splenic artery b. Transverse mesocolon c. Transverse colon d. Fourth part of duodenum

38. 3. A posteriorly perforating peptic ulcer will most likely produce peritonitis in the following: a. Greater sac b. Lesser sac c. Bare area of liver d. Morrison’s pouch 4. Which of the following arteries supplies the fundus of the stomach? a. Right gastric artery b. Splenic artery c. Short gastric arteries d. Gastroduodenal artery

39. 5. Which cell of gastric gland gives it a beaded appearance ? a. Zymogenic b. Oxyntic c. Mucus cells d. Columnar cell 6. Cardiac orifice of stomach lies behind one of the following costal cartilages: a. Left fifth b. Left seventh c. Left eighth d. Right eighth

40. 1. b 2. d 3. b 4. c 5. b 6. b