CBL –STOMACH & DUODENUMBY

Dr. Abdul Waheed Ansari

Chairperson & Prof. Anatomy,

RAKCOMS.

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The learning out comes for the CBL are:-

• 1. Identifying the gross features and microscopic picture of stomach and relate it to the clinical cases.

• 2. Relate the relations of stomach and its blood supply, nerve supply and lymphatic drainage with the clinical scenarios.

• 3. Correlate the gross features of duodenum and histological differences with other segments of GIT.

• 4. The blood supply, lymphatic drainage and its nerve supply.

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A case of upper gastrointestinal bleeding

• A 68-year-old male was admitted to the hospital with a chief complaint of emesis of bright red blood.

• The patient reported that he was shopping when he began throwing up blood at the store.

• He denied any associated pain, melena (passing of black tarry stools), hematochezia (passing of fresh blood from anus), liver disease, or prior episodes.

• The patient reported some lightheadedness with standing, but denied chest pain, shortness of breath, and visual disturbances.

• He was on Indomethacin for his gout problem since one month.

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The gross anatomy of stomach

• It is the most dilated part of digestive system. It is a reservoir of food, it produces acid and enzymes for the food to be digested and mixed with the bile for fat metabolism in the duodenum.

• Stomach is continuous above with the esophagus and below with the first part of small intestine- duodenum.

• Stomach is covered by peritoneum and hanging folds are the omenta- greater and lesser omenta.

• Stomach is anchored to the undersurface of diaphragm by gastro phrenic & gastro colic ligaments.

• The wall of stomach is made up of serosa, muscularis externa, submucosa , muscularis interna and mucosa.

• It is supplied by branches from coeliac artery.

• The nerve supply comes from vagus nerve and coeliac ganglion.

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The blood supply of stomach

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The following groups of lymph nodes are associated with stomach:-• The lymphatic drainage is very important because

the cancer can spread to the various part of the body through lymphatic system and the staging of the stomach cancer involves regional lymph nodes.

• The lymph nodes surrounding the lesser curvature of the stomach drained directly into the celiac nodes.

• The lymph nodes surrounding the greater curvature and the fundus drained into the splenic nodes which then drained into the celiac nodes.

• 1. Splenic group

• 2. Cardiac group

• 3. Coeliac group

• 4. Duodenal group

• 5. Hepatic group12/18/2014 6

The vagal innervation of stomach carries parasympathetic supply to acid producing gastric mucosa

• The truncal vagotomy is performed to cut off the acid secretion fibers.

• As a result there will be stasis in the stomach and gall bladder leading to formation of ileus and cholelithiasis.

• Peptic ulcers are defects in the gastric or duodenal mucosa that extend through the muscularis mucosa.

• The epithelial cells of the stomach and duodenum secrete mucus in response to irritation of the epithelial lining and as a result of cholinergic stimulation.

• The superficial portion of the gastric and duodenal mucosa exists in the form of a gel layer, which is impermeable to acid and pepsin.

• Other gastric and duodenal cells secrete bicarbonate, which aids in buffering acid that lies near the mucosa.

• Prostaglandins of the E type (PGE) have an important protective role, because PGE increases the production of both bicarbonate and the mucous layer.

• The study of H pylori has revealed that it is a major part of the triad, which includes acid and pepsin, that contributes to primary peptic ulcer disease. When H pylori colonizes the gastric mucosa, inflammation usually results.

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The histology of stomach

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• Mucous secreting cells (goblet cells)- Line the luminal surface of the stomach and gastric pits and gastric glands. Produce mucus and bicarbonate.

• Mucous neck cells- Present in the neck of the gland. Produce mucin.

• Parietal cells (oxyntic cells)- Distributed throughout the length of the gland, but numerous in the middle portion. Large, rounded cells with eosinophilic cytoplasm and centrally located nucleus. Produce gastric acid.

• Chief cells (peptic or zymogenic cells)- Clustered at the base of the gland. Identified by basally located nuclei and strongly basophilic granular cytoplasm. Produce pepsinogen, digests protein.

Types of cells present in the stomach:

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A case of perforation of gastric ulcer• A 42-year-old person was admitted to the hospital after visiting the emergency room

complaining of severe epigastric pain and pain over her right shoulder.

• She had a history of gastric ulcer which had been treated previously with medication, but on questioning, she admitted that she had been so busy recently that she had forgotten to refill her prescription and had not taken her medication in time.

• As a result of the history and physical findings, the physician suspected that she was suffering from a perforated gastric ulcer.

• Gastroscopy was performed which confirmed the diagnosis.

• When the surgeon examined the patient's stomach during the surgery, she found a small perforation on the posterior aspect of the body of the stomach near the lesser curvature.

• The perforation was repaired and, in addition, a vagotomy was performed.

• During the vagotomy, the surgeon found it necessary to cut the left gastric artery and ligate it.12/18/2014 10

The stomach bed and its relations

• The structure located posterior to the stomach could be damaged by gastric juices leaking from a perforated ulcer on the posterior wall of the stomach.

• These organs would include the pancreas, the left suprarenal gland, the upper part of the left kidney, the diaphragm, the splenic artery, and its branches, and maybe the spleen.

• Erosion of the wall of the splenic artery is of particular concern because it could lead to severe internal hemorrhage and rapid exsanguination.

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The pain felt at shoulder is a referred pain

• The shoulder pain was likely referred pain that occurred due to irritation of the diaphragm by gastric juices.

• The diaphragm is innervated by the phrenic nerves which arise from cervical nerves 3, 4, and 5.

• These cervical nerves also contain nerves that innervate the shoulder region; thus, the shoulder is a common location for referred pain from the diaphragm.

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The collateral circulation around the stomach

• If the left gastric artery is occluded due to surgical ligation, collateral circulation from the right gastric artery, right gastroomental artery (a branch of the gastro duodenal artery), and the left gastroomental and short gastric arteries (branches of the splenic artery) is usually adequate to compensate for loss of flow through the left gastric artery.

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A case of carcinoma of head of pancreas

• M.S., a generally healthy 74-year-old woman, visited her physician with the following complaints: progressive jaundice over the last week or so, frequent bowel movements with pale, greasy feces, a lack of energy, weight loss, and back pain.

• The physician ordered a series of tests, which suggested that the jaundice was of an obstructive, not metabolic, nature.

• Abdominal ultrasound demonstrated the presence of a growth on the head of the pancreas, and further tests indicated that the lesion was a pancreatic carcinoma .

• After consultation with a surgeon, M.S. elected to have a cholecystojejunostomy performed to correct the obstruction and prevent the discomfort and pruritis that usually accompany obstructive jaundice.

• The pancreatic tumor was deemed inoperable.

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The first segment of small intestine is duodenum

• The duodenum is the first part of the small intestine, followed by the jejunum and ileum (in that order); it is also the widest and shortest (25 cm) part.

• The duodenum is a C-shaped or horseshoe-shaped structure that lies in the upper abdomen near the midline.

• The first (superior) part, or duodenal bulb (5 cm), which is connected to the undersurface of the liver (porta hepatis) by the hepatoduodenal ligament, containing the proper hepatic artery, portal vein, and common bile duct (CBD); the quadrate lobe (segment IV) of the liver and the gallbladder are in front, whereas the CBD, the portal vein (PV), and the gastroduodenal artery (GDA) are behind it.

• The second (descending) part (7.5 cm), which has an upper and a lower genu (flexure); the transverse mesocolon and transverse colon are in front, and the right kidney and inferior vena cava (IVC) are behind it; the head of the pancreas lies in the concavity of the duodenal C. The major duodenal papilla opens in the posterior wall of 2nd part of duodenum draining the bile and pancreatic juices.

• The third (horizontal) part (10 cm) runs from right to left in front of the IVC and aorta, with the superior mesenteric vessels (the vein on the right and the artery on the left) in front of it.

• The fourth (ascending) part (2.5 cm) continues as the jejunum.

• Except for its first part, the duodenum is largely retroperitoneal and therefore fixed; it has no mesentery and is covered by peritoneum only on its anterior surface.12/18/2014 15

The blood supply, innervation and lymphatic drainage of duodenum

• The gastroduodenal artery arises from coeliac trunk.

• The supraduodenal artery is a branch from gastroduodenal artery.

• The superior and inferior pancreaticoduodenal arterial arches are from both coeliac and superior mesenteric arteries.

• The corresponding veins drain into superior mesenteric vein.

• Innervation to duodenum is derived from coeliac ganglion and vagi nerves.

• The lymphatic drainage is to the gastroduodenal group, pancreaticoduodenal and hepatic group of lymph nodes.

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The histology of duodenum

• The wall of the duodenum contains the same 4 layers that are seen in the remainder of the small bowel--namely, the mucosa (lined with columnar epithelium, containing lamina propria and muscularis mucosa), the submucosa, the muscularis propria (with inner circular and outer longitudinal layers), and the serosa (only on its anterior surface).

• The duodenal mucosa is characterized by the presence of Brunner’s glands, which secrete mucus.

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A case of duodenal ulcer • A 40 year-old male with a long history of duodenal ulcer problems was brought in for emergency surgery to control severe hemorrhage into the peritoneal cavity.

• The surgeons found that erosion by the ulcer of a vessel passing behind the first part of the duodenum was the source of the hemorrhage.

• Which of the following vessels passes behind the first part of the duodenum and would need to be clamped off to control the bleeding?

• It is gastroduodenal artery bleeding from a perforated duodenal ulcer.

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References:- Essential Clinical Anatomy-4th edition-Keith Moore (pages143-152)

• http://teachmeanatomy.info/abdomen/viscera/stomach/blood-supply-to-the-stomach-arteries/

• http://emedicine.medscape.com/article/181753-overview#aw2aab6b2b2aa

• http://library.med.utah.edu/WebPath/GIHTML/GI421.html

• http://www.cytochemistry.net/microanatomy/digestive/stomach.htm

• http://www.colorado.edu/intphys/iphy3415/histology/#digestive

• http://www.udel.edu/biology/Wags/histopage/illuspage/igi/intestinesppt.htm

• http://web.uni-plovdiv.bg/stu1104541018/docs/res/skandalakis'%20surgical%20anatomy%20-%202004/Chapter%2016_%20Small%20Intestine.htm

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