GI anatomy

Question 1

Dimensions of the oral cavity

Answer 1

• Roof - hard and soft palaes •Posterior : ‘Oropharyngeal isthmus’ opens into the oropharynx • Border between mouth and pahrynx is marked with palatoglossal arch • Closure of oropharyngeal isthmus via palatoglossus(muscle of soft palate)

Question 2

Thyroglossal duct

Answer 2

• Terminal sulcus - apex of the V is the foramen cecum • Thyroglossal duct connects the foramen cecum to the thyroid gland, if persists causes thyroglossal duct cysts.

Question 3

The tongue

Answer 3

All have taste buds on their surface except filliform. 1. Fungiform papillae - Round and large - along margins of tongue 2. Filiform papillae - small, mucosal projections 3.Foliate papillae - Liner folds of mucosa, sides of tongue 4. Vallate papillae - Blunt ended, cylindrical -largest -anterior to the terminal sulcus

Question 4

Salivary glands

Answer 4

1. Parotid glands - outside of oral cavity - external surface of masseter and buccinator muscle 2. Submandibular - below mylohyoid - outside oral cavity -secreates serous fluid and mucus 3. Sublingual (smalles) is lateral to submandibular duct - 5% saliva of oral cavity

Question 5

Parotitis

Answer 5

• infllammation of the parotid gland • Caused by mumps • May cause blockage of salivary duct calculi

Question 6

development of GI tract

Answer 6

Foregut - coeliac trunk of abdominal aorta Midgut - superior mesenteric Hindgut - inferior mesenteric

Question 7

The oesophagus

Answer 7

1. Cervical - continous with oropharynx 2. Thoracic - T1-T10 3. Abdominal (oesophageal hiatus to cardia of stomach)

Question 8

Three constrictions of oesophagus

Answer 8

1. Cervical (C5/C6) due to cricoid cartilage 2. Thoracic - due to aortic arch 3. Abdominal at the oesophageal hiatus

Question 9

oesophageal atresia

Answer 9

• Absence of contiguity with oesophagus due to imapproprate divison of the foregut into trachea and oesophagus • Congential obstruction of oesphagus into a blind-ended pouch • Tracheoesophageal fistula - an abnormal connection between the esophagus and trachea

Question 10

Oesophageal stenosis/stricture

Answer 10

Narrowing or tightening of the oesophagus, making swallowing difficult assoc with • GOR (gastrooesophageal reflux disease) - stomach acid affects oesophagus • Hiatus hernia - when part of the stomach squeezes into the chest through an opening in the diaphragm

Question 11

The deriviatives of the foregut

Answer 11

• Stomach •Duodenum • Liver • Gallbladder •Pancreas •Spleen

Question 12

Pyloric stenosis

Answer 12

• Pylorus is the muscular valve between the stomach and small intestine •idiopathic thicking of the pyloric musculature results in progressive gastric outlet obstruction • Hypertrophic pylorus can be palpated as olive size mass in the right upper quadrant • Barium meal shows elongated pylorus with narrown lumen • Ultrasound is the main modality of choice to measure changes in wall thickness

Question 13

The biliary tree

Answer 13

•empty into descending duodenum • Left and right hepatic duct until to form common hepatic duct • Common hepatic duct + cystic duct = common bile duct • Common bile duct joins with pancreatic duct to enter the descending duodenum at the major duodenal papilla

Question 14

Biliary atresia

Answer 14

• one or more bile ducts are abnormally narrow, or absent - obliteration of common duct - atresia of hepatic duct • obstruction to bile flow •Build up of bile leads to cirrhosis / jaundice/hepatomegaly/splenomegaly

Question 15

Annular pancreas

Answer 15

• second part of the duodenum is surrounded by a ring of pancreatic tissue continous with the head of the pancreas • Embryological failure of the ventral bud to rotate with the duodenum •portion of the pancreas can constrict the duodenum and impair the flow of food to the rest of the intestines

Question 16

Splenunculus

Answer 16

• Accessory spleen • small nodules of spleen detached • benign and asymptomatic

Question 17

Abdominal planes

Answer 17

Question 18

Lobes of the liver

Answer 18

The quadrate and caudate lobes are described as arising from the right lobe

• Functionally, however, they are said to be related to the left lobe
• In relation to their blood supply, venous drainage and the hepatic ducts

Question 19

Peritoneal reflections of the liver

Answer 19

Question 20

Production and secretion of bile

Answer 20

Bile acts to digest and absorb fat and fat-soluble vitamins in the small intestine AND eliminate waste products, including bilirubin

• Produced and secreted by hepatocytes at a constant rate of about 40 mL per hour

– Hepatocytes secrete bile into canaliculi which flows into bile ducts

• Stored and concentrated (5-fold) in the gallbladder when digestion is not taking place

Question 21

the Pancreas

Answer 21

• Main pancreatic duct – begins at tail and runs to head, receiving numerous tributaries

• Opens into 2nd part duodenum with bile duct on the major duodenal papilla
• Accessory duct – when present – drains upper part of head and opens into duodenum, above main duct, on minor duodenal papilla
• Accessory duct frequently communicates with the main duct