Stomach and intestines

Question 1

What is the stomach?

Answer 1

An intraperitoneal digestive organ located between the oesophagus and the duodenum.
It has a ‘J’ shape, and features a lesser and greater curvature. The anterior and posterior surfaces are smoothly rounded with a peritoneal covering.

Question 2

What are the rugae?

Answer 2

The inner layer of the stomach is full of wrinkles known as rugae (or gastric folds). Rugae both allow the stomach to stretch in order to accommodate large meals and help to grip and move food during digestion.

Question 3

Where is the stomach positioned?

Answer 3

Primarily lies in the epigastric and umbilical regions, however, the exact size, shape and position of the stomach can vary from person to person. Attached to the liver via a sheet of fat (lesser omentum). The lesser omentum carried the hepatic artery, hepatic portal vein and bile duct.

Question 4

What makes up the gastric bed?

Answer 4

Gastric bed - lesser sac (behind the stomach), pancreas (behind the lesser sac), splenic artery, and part of the duodenum.

Question 5

What are the areas of the stomach?

Answer 5

Cardia – surrounds the superior opening of the stomach at the T11 level.
Fundus – the rounded, often gas filled portion superior to and left of the cardia.
Body – the large central portion inferior to the fundus.
Pylorus – This area connects the stomach to the duodenum. It is divided into the pyloric antrum, pyloric canal and pyloric sphincter. The pyloric sphincter demarcates the transpyloric plane at the level of L1.

Question 6

What are the features of the greater curvature of the stomach?

Answer 6

Forms the long, convex, lateral border of the stomach. Arising at the cardiac notch, it arches backwards and passes inferiorly to the left. It curves to the right as it continues medially to reach the pyloric antrum. The short gastric arteries and the right and left gastro-omental arteries supply branches to the greater curvature.

Question 7

What are the features of the lesser curvature of the stomach?

Answer 7

Forms the shorter, concave, medial surface of the stomach. The most inferior part of the lesser curvature, the angular notch, indicates the junction of the body and pyloric region. The lesser curvature gives attachment to the hepatogastric ligament and is supplied by the left gastric artery and right gastric branch of the hepatic artery.

Question 8

What makes up the stomach’s arterial blood supply?

Answer 8

The arterial supply to the stomach comes from the celiac trunk and its branches. Anastomoses form along the lesser curvature by the right and left gastric arteries. Right gastric comes from common hepatic, whereas left gastric comes directly from the celiac trunk. Along the greater curvature by the right and left gastro-omental arteries. Right gastroepiploic branches from gastroduodenal from common hepatic. Left gastroepiploic branches from splenic.

Question 9

What is the venous system for the stomach?

Answer 9

The veins of the stomach run parallel to the arteries. The right and left gastric veins drain into the hepatic portal vein. The short gastric vein, left and right gastro-omental veins ultimately drain into the superior mesenteric vein.

Question 10

What is the foregut’s (and therefore the stomach’s) innervation?

Answer 10

The foregut receives a sympathetic nerve supply from the Greater Splanchnic Nerve (T5-T9) and parasympathetic supply from the vagal trunks (CNX).

Question 11

What is the lymph drainage system of the stomach?

Answer 11

The gastric lymphatic vessels travel with the arteries along the greater and lesser curvatures of the stomach. Lymph fluid drains into the gastric and gastro-omental lymph nodes found at the curvatures.
Efferent lymphatic vessels from these nodes connect to the coeliac lymph nodes, located on the posterior abdominal wall.

Question 12

What is a barium meal?

Answer 12

Patient doesn’t eat for 12 hours so that stomach is completely empty. They are given barium sulphate which is not absorbed into the body but coats the lining of the stomach and absorbs X-rays so that it shows white on the image. They are then given a fizzy drink to dilate the stomach with gas.

Question 13

How does liver disease affect the veins?

Answer 13

In disease of the liver, the portal venous channels in the liver become progressively smaller until they are insufficient for normal blood flow. The venous blood from the bowel will then flow up the veins in the oesophagus and into the SVC (a porto-systemic shunt). The veins in the oesophagus distend to form oesophageal varices: varicose veins of the oesophagus which bleed easily.

Question 14

What is a pyloric stenosis?

Answer 14

Some children, in the first six weeks of life, over develop the pyloric sphincter and the stomach cannot empty into the duodenum (pyloric stenosis). After feeding, when the stomach contracts, food is forced out of the mouth (projectile vomiting). Because the child is not getting any nutrition, they are always hungry and eager to feed.

Question 15

Where do peptic ulcers commonly form?

Answer 15

The posterior wall of the first part of the duodenum. If the ulcer erodes through the duodenal wall it may erode into the gastroduodenal artery and cause very brisk bleeding.

Question 16

Which structure(s) passes through the diaphragm alongside the oesophagus?

Answer 16

The vagal trunks, inferior oesophageal artery and vein.

Question 17

What structure attaches the stomach to the liver?

Answer 17

Lesser omentum

Question 18

Which structures lie in front of the stomach?

Answer 18

Left lobe of the liver, anterior abdominal wall

Question 19

Which structures lie behind the stomach?

Answer 19

The lesser sac, behind the lesser sac is the pancreas and diaphragm.

Question 20

What is a porto-systemic anastomosis?

Answer 20

It is a vein which joins to the hepatic portal system (so can carry blood to the liver) to the systemic system. It can take blood from the bowel and bypass the liver to return the blood to the heart.

Question 21

What is the small intestine?

Answer 21

The small intestine is an organ located within the gastrointestinal tract. It is approximately 6.5m in the average person and assists in the digestion and absorption of ingested food.

Question 22

How can the small intestine be anatomically divided?

Answer 22

It extends from the pylorus of the stomach to the ileocaecal junction, where it meets the large intestine at the ileocaecal valve. Anatomically, the small bowel can be divided into three parts; the duodenum, jejunum and ileum.

Question 23

How mobile is the small intestine?

Answer 23

The duodenum is mostly retroperitoneal, fixed and constant. The rest of the small intestine, the jejunum and ileum are attached with a mesentery and are relatively mobile. This means that this part of the bowel is often involved in hernias and can become twisted (volvulus).

Question 24

How is the small intestine adapted for its function?

Answer 24

Organ of nutrient absorption and needs a high surface area. It is long. The mucosa has multiple mucosal folds (plicae circularis) and there are villi on the mucosal folds and microvilli on each individual epithelial cell. Plicae circularis are more prominent in the jejunum than in the ileum. This is because less absorption happens here.

Question 25

What is the duodenum?

Answer 25

Runs from the pylorus of the stomach to the duodenojejunal junction. Form a ‘C’ shape, that is around 25cm long, and which wraps around the head of the pancreas.

Question 26

How can the duodenum be anatomically divided?

Answer 26

Superior (L1): known as the cap, first 3cm are not retroperitoneal, common site of duodenal ulceration.
Descending (L1-L3): curves inferiorly around the head of the pancreas. Marked by the major duodenal papilla – the opening at which bile and pancreatic secretions to enter from the ampulla of Vater.
Inferior (L3): moves laterally and crosses over the inferior vena cava and aorta.
Ascending (L3-L2): joins the jejunum at a sharp turn known as the duodenojejunal flexure.

Question 27

What is the blood supply of the duodenum?

Answer 27

Blood supply from gastroduodenal artery (branch of the coeliac trunk) and inferior pancreaticoduodenal artery (branch of superior mesenteric artery). Split by distance to major duodenal papilla.

Question 28

What are the major differences between the ileum and the jejunum?

Answer 28

JEJUNUM: Located in upper left quadrant, Thick intestinal wall, Longer vasa recta (straight arteries), Less arcades (arterial loops), Red in colour
ILEUM: Located in lower right quadrant, Thin intestinal wall, Shorter vasa recta, More arcades, Pink in colour

Question 29

What is the blood supply of the ileum and jejunum?

Answer 29

The arterial supply to the jejunoileum is from the superior mesenteric artery.

Question 30

What are arcades and vasa recta?

Answer 30

The superior mesenteric artery arises from the aorta at the level of the L1 vertebrae immediately inferior to the coeliac trunk. It moves in between layers of mesentery, splitting into approximately 20 branches. These branches anastomose to form loops, called arcades. From the arcades, long and straight arteries arise, called vasa recta.

Question 31

What is the lymphatic drainage for the duodenum?

Answer 31

Lymphatic drainage is to the pancreatoduodenal and superior mesenteric nodes.

Question 32

What is the lymphatic drainage for the jejunum and ileum?

Answer 32

Lymphatic drainage is into the superior mesenteric nodes.

Question 33

What’s the peritoneal disposition of the large intestine?

Answer 33

The large intestine starts at the ileo-caecal valve in the right iliac fossa. It alternates between a retroperitoneal and mesenteric disposition: the AC and DC are normally retroperitoneal and the transverse and sigmoid colon lie within a mesentery.

Question 34

What is the cecum?

Answer 34

Located between the ileum and the ascending colon. Acts as a reservoir of chyme. Found in the right iliac fossa. Between the cecum and ilium is the ileocecal valve. This structure prevents reflux of large bowel contents into the ileum during peristalsis.

Question 35

What is the arterial and venous supply of the cecum?

Answer 35

Arterial supply is from the ileocolic artery, a branch of the superior mesenteric artery. It subsequently divides into anterior and posterior cecal arteries.
Venous drainage is provided by the corresponding ileocolic vein, and empties into the superior mesenteric vein.

Question 36

What is the innervation to the cecum?

Answer 36

Innervation by the ileocolic branch of the superior mesenteric plexus, which follows the same course as the ileocolic artery and carries vagal and sympathetic nerve fibres.

Question 37

What is the lymphatic drainage to the cecum?

Answer 37

Lymph from the cecum drains into the ileocolic lymph nodes.

Question 38

What is the colon?

Answer 38

It receives digested food from the small intestine, from which it absorbs water and electrolytes to form faeces. Divided into four parts – ascending, transverse, descending and sigmoid.

Question 39

What are the anatomical parts of the colon?

Answer 39

Ascending colon: a retroperitoneal structure which ascends superiorly from the cecum. When it meets the right lobe of the liver, it turns 90 degrees to move horizontally. This turn is known as the right colic flexure.
Transverse colon: from the right colic flexure to the spleen, where it turns another 90 degrees to point inferiorly. This turn is known as the left colic flexure. Variable in position and intraperitoneal.
Descending colon: moves inferiorly towards the pelvis. Retroperitoneal.
Sigmoid colon: The 40cm long sigmoid colon is located in the left lower quadrant of the abdomen, extending from the left iliac fossa to the level of the S3 vertebra. Attached by a mesentery.

Question 40

What are the unique characteristics of the large intestine?

Answer 40

The outer longitudinal muscle layer forms three bands, the taenia coli which start at the base of the appendix and end at the rectum
Between the longitudinal taenia coli the circular inner layer bulges repeatedly between them to form characteristic ‘haustrations’
On the colon there are two rows of ear-like pads of fat, known as appendices epiploicae

Question 41

What is the blood supply to the colon?

Answer 41

As a general rule, midgut-derived structures are supplied by the superior mesenteric artery, and hindgut-derived structures by the inferior mesenteric artery.
Ascending colon receives blood from the ileocolic and right colic arteries (branches of superior mesenteric)
Transverse colon is supplied by the right and middle colic artery (branches of superior mesenteric) and the left colic artery (from inferior mesenteric)
Descending colon is supplied by the left colic artery (from inferior mesenteric)
Sigmoid colon supplied by the sigmoid arteries (from inferior mesenteric)

Question 42

What is the venous drainage to the colon?

Answer 42

Ascending colon – ileocolic and right colic veins, which empty into the superior mesenteric vein.
Transverse colon – middle colic vein, which empties into the superior mesenteric vein.
Descending colon – left colic vein, which drains into the inferior mesenteric vein.
Sigmoid colon – drained by the sigmoid veins into the inferior mesenteric vein.
Superior and inferior mesenteric veins empty into the hepatic portal vein.

Question 43

What is the innervation of the colon?

Answer 43

Midgut-derived structures (ascending colon and proximal 2/3 of the transverse colon) receive their sympathetic, parasympathetic and sensory supply via nerves from the superior mesenteric plexus.
Hindgut-derived structures (distal 1/3 of the transverse colon, descending colon and sigmoid colon) receive their sympathetic, parasympathetic and sensory supply via nerves from the inferior mesenteric plexus

Question 44

What is the lymphatic drainage of the colon?

Answer 44

The lymphatic drainage of the ascending and transverse colon is into the superior mesenteric nodes. The descending colon and sigmoid drain into the inferior mesenteric nodes.

Question 45

How are the foregut, midgut, hindgut split?

Answer 45

Foregut: oesophagus, stomach, liver, gallbladder, bile ducts, pancreas and proximal duodenum.
Midgut: distal duodenum, jejunum, ileum, cecum, appendix, ascending colon, and proximal 2/3 of transverse colon.
Hindgut: distal third of the transverse colon and the splenic flexure, the descending colon, sigmoid colon and rectum

Question 46

What is the Sacral promontory?

Answer 46

The inwardly projecting anterior part of the body of the first sacral vertebra. The aorta bifucates just above here.

Question 47

What is a barium enema?

Answer 47

The patient is given strong laxatives so that the colon is completely empty. Barium sulphate is the introduced through the anal canal and is allowed to flow back to the ileo-caecal valve. Air is then pumped in to distend the bowel.

Question 48

Where will cancer of the colon spread to?

Answer 48

Carcinoma of the colon and rectum spread directly to the bloodstream, through the portal circulation to the liver but also through the lymph vessels to regional lymph nodes.

Question 49

What is Meckel’s diverticulum?

Answer 49

In embryology the yolk sac is attached to the bowel exactly half way along its length. In 2% of adults the connection persists as a diverticulum (blind tube) attached 2 feet from the ileo-caecal junction, it is often 2 inches long. It can contain gastric mucosa and is a site for peptic ulcers and causes abdominal pain.

Question 50

The structures on a mesentery are at risk of what problem?

Answer 50

Bowel which is on a mesentery may twist around on itself and cause blockage of the draining vein. The result is an increase in capillary hydrostatic pressure, fluid leakage into the tissue and eventually death of the tissue. Most commonly occurs in the sigmoid colon.

Question 51

Which foodstuffs are absorbed through the lymphatic system?

Answer 51

Lipids

Question 52

Which part of the bowel is supplied by sacral nerves 2, 3 and 4?

Answer 52

The hind gut.