GI Anatomy

Question 1

What is rectus abdominus?

Answer 1

• Runs from costal cartilage margin and sternum to the pubis. There is a rectus sheath. They run either side of the midline and are separated by the linea alba. It is also separated by tendinous intersections.

Question 2

What is external oblique muscle?

Answer 2

• Runs down and inwards, it originates from ribs 5 to 12 and inserts into iliac crest, where it merges to form the external oblique apononerous.

Question 3

What is internal oblique muscle?

Answer 3

• Smaller and thinner, upwards and inwards.

Question 4

What is transveralis abdominus?

Answer 4

• It is the deepest muscle, and runs transversally.

- Below it is the transversalis apononerous.

Question 5

What divides the abdo cavity into 9 sections?

Answer 5

• Midclavical point to mid inguinal point vertically and sub costal plane and mid tubercle plane horizontally.

Question 6

What supplies the foregut?

Answer 6

• The greater splanchnic nerve - pain is felt anteriorly to the organ.

Question 7

What supplies the midgut?

Answer 7

• The lesser splanchnic nerve - pain is felt in the epigastric region.

Question 8

What supplies the hindgut?

Answer 8

• The lowest splanchnic nerve - pain is felt in the suprapubic region.

Question 9

How is pain felt in the peritoneum?

Answer 9

• More localised, pain is supplied by the sensory nerves in the skin above.

Question 10

What is the inguinal canal made up of?

Answer 10

• Deep ring, superfical ring, floor, roof, anterior and posterior wall.

Question 11

What makes up the structure of the inguinal canal?

Answer 11

• Roof = internal oblique and transversalis
• Floor = inguinal ligmanet
• Anterior = external oblique
• Posterior = conjoint tendon

Question 12

What travels through the inguinal canal?

Answer 12

• Males = spermatic cord, vas deferns and testicular artery.
• Females = round ligament of the ovaries.

Question 13

What defines a hernia?

Answer 13

• Inferior epigastric artery - medial = direct, lateral = indirect

Question 14

What is the peritoneum and peritoneal cavity?

Answer 14

• Visceral peritoneum = covers the bowel and mesenteries.
• Pariteal peritoneum = covers the inside surface of the abdo cavity.
• Space between the two is the peritoneal cavity - important for the spread of disease as allows the build up of fluid, exudate and pus - allows the spread of cancer cells and disease.

Question 15

What structures are fixed and free moving in the abdomen?

Answer 15

• Fixed structures = ascending and descending colon.

- Moving structures = with mesentery = appendix and small bowel.

Question 16

What is the peritoneum split into?

Answer 16

• Greater sac - split into two and is bigger.
• Lesser sac - this lies behind the stomach and the lesser omentum. It is connected to the greater sac by the epiploic foramen - it allows the stomach to move more freely against structures posterior and inferior.

Question 17

What is the lesser omentum?

Answer 17

• Runs from the diaphragm next to the oesophagus over the liver to the lesser curvature of the stomach.
• Contains the porta hepatitis on the free edge and the epiploic also lies posterior to the free edge.
• It is fatty and contains blood vessels.

Question 18

What is found on the lower quadrant of the abdo cavity?

Answer 18

• Inside finds the remnants of the umbilical arteries - midline umbilical remnants and the medial umbilical remnants.

Question 19

What is contained in the porta hepatitis?

Answer 19

• Lies on the free edge of the lesser omentum and contains the bile duct, portal vein and hepatic artery.

Question 20

Where is the spleen located?

Answer 20

• Lies lateral to the stomach and is attached to the greater curvature of the stomach by the greater omentum- .
• The greater omentum runs from the greater curvature to the retroposterior wall.
• It’s find deep to the rib cage and above the costal margin.

Question 21

What is the foregut?

Answer 21

• Mouth to 2/3 of the duodenum - supplied by the coeliac trunk and the greater splenic artery.
• Includes the oesophagus, stomach, and first 2/3 of the duodenum.

Question 22

What is the midgut?

Answer 22

• Last 1/3 of the duodenum to the first 2/3 of the transverse colon - supplied by the superior mesenteric artery and the lesser splenic artery.
• Includes the last 1/3 of the duodenum, jejunum, ileum, cecum, appnedix, ascending colon and the first 2/3 of the transverse colon.

Question 23

What is the hindgut?

Answer 23

• Last 1/3 of the transverse colon, the descending colon, sigmoid colon and rectum - supplied by the inferior mesenteric artery and the lowest splenic nerve.

Question 24

What is Mcburney’s point?

Answer 24

• 2/3 along the line from the anterior superior iliac spine to the umbilical
• Base of the appendix

Question 25

Where is the umbilicus found?

Answer 25

• L3

Question 26

What is the foetal blood supply?

Answer 26

• From the placenta through the umbilical veins (oxygenated) to the right atrium shunted to the left atrium, left ventricle, aorta, common iliac arteries, umbilical arteries and then iliac vein.

Question 27

What does the coeliac trunk supply?

Answer 27

• The foregut, liver and part of the pancreas.

- Drainage into the portal vein back to the liver.

Question 28

What are the parts of the stomach?

Answer 28

• Oesophagus into the body, fundus and pylorus (made of pyloric antrium and pyloric spinchter) and then into the duodenum.
• The inside of the stomach - the mucosal lining is rugae.

Question 29

What is the caudate lobe?

Answer 29

• Independent part of the liver supplied by the right and left hepatic artery and the portal vein.

Question 30

What is a barium meal examination?

Answer 30

• Patient doesn’t eat for 12 hours pre procedure.
• Patient swallows barium sulphate that doesn’t absorb and therefore lines the stomach and can be absorbed by the x ray.
• The stomach can be inflamed by drinking a fizzy drink.

Question 31

What is the clinical relevance of cirrhosis?

Answer 31

• Lower 1/3 of the oesophagus drains into the superior vein cava or the portal vein. In cirrhosis the portal vein channels the the liver become progressively smaller in disease so the blood is insufficient and this means that blood from the bowel flows into the oesophagus and therefore causing dilation of the vessels leading varicose veins that can bleed easily.

Question 32

Small Intestine

Answer 32

• Made up of the duodenum, ileum and the jejunum.
• The duodenum is retroperitoneal where the as the i and j are mesenteric.
• Important as these are the organs of absorption so they need large surface area - created through long, multiple mucosal folds and villi/microvilli.

Question 33

What are the pliace circularis?

Answer 33

• Multiple mucosal folds - more pronounced in the jejunum than the ileum.

Question 34

What is the large bowel made up of?

Answer 34

• From the ileocecal valve to the rectum.

- Either mesenteric (the transverse/sigmoid colon) or retroperitoneal (ascending/descending colon)

Question 35

What characteristics make up the large bowel?

Answer 35

• Outer layers of longitudinal muscle called teniae coli that run from the base of the appendix to the rectum.
• Buldges
• Fatty tags

Question 36

What feeds into the portal vein?

Answer 36

• Splenic vein, inferior mesenteric vein and superior mesenteric vein

Question 37

What feeds into the common bile duct?

Answer 37

• The cystic duct from the gallbladder and the right and left hepatic ducts, it then joins the pancreatic duct to release into the duodenum

Question 38

What is the coeliac trunk?

Answer 38

• First anterior branch of the abdominal aorta, after T12 becomes the hepatic artery (which divides into the left and right hepatic in the liver), left gastric and splenic artery

Question 39

How many lobes of the liver are there?

Answer 39

• From superior surface - 2 lobes, right and left with right being bigger.
• From inferior surface - 4 lobes - caudate (Top) and quadrate (bottom) plus right and left.

Question 40

What is the pancreas made up of?

Answer 40

• Tail, body, neck and head