1.2 Anatomy of the Abdomen

Question 1

List the 3 sections of the oesophagus and potential constrictions at each

Answer 1

1. Cervical: constriction can be caused by cricopharyngeus muscle
2. Thoracic portion (bulk): constriction can be caused by bronchi-aortic arch
3. Abdominal portion: constriction caused by oesophageal hiatus of diaphragm (T10)

Question 2

What ligament allows for movement of the oesophagus whilst keeping it tethered as it enters the thorax?

Answer 2

Phreno-oesophageal ligament

Question 3

Describe the 2 types of oesophageal hernias

Answer 3

1. Sliding hiatal hernia: failure of the phreno-esophageal ligament to keep the stomach in place (commonly aquired). Often due to a displaced LES

• Symptoms: pyrosis (“heartburn”) and dysphagia

2. Rolling (paraesophageal) hernia: fundus of stomach protrudes through the diaphragm to form a pouch (less commonly aquired)

• Symptoms: diffuse pain
• Medical Emergency!

Question 4

Which type of esophageal hernia is a medical emergency and why?

Answer 4

Rolling: because the fundus of the stomach can become necrotic due to the tight constriction

Question 5

What are the pathways of venous drainage for the oesophagus?

Answer 5

1. Most drain through systemic veins:

esophageal v ➞ azygous v ➞ SVC

2. Veins lower down drain through the portal system:

esophageal v ➞ L gastric v ➞ portal v ➞ liver ➞ hepatic v ➞ IVC

Question 6

What is a varix?

Answer 6

An enlarged and tortuous vein, unnaturally swollen

Question 7

What is the primary cause of oesophageal varicies and why?

Answer 7

Portal hypertension

The oesophagus has porto-systemic anastomoses ➞ veins of portal circulation (draining to liver) and veins of systemic circulation (draining to heart) meet to drain the same structures

If there is hepatic fibrosis (e.g cirrhosis), scar tissue replaces normal tissue, blocking the flow of blood exiting via the hepatic vein. This causes portal hypertension.

As the veins draining the portal system do NOT have valves, this results in back pressure into the systemic circulation, seen as a varicies

Question 8

List 3 signs that may be seen on examination of a patient with portal hypertension

Answer 8

Oesophageal varices

Rectal varices (haemorrhoids)

Caput medusae

Question 9

Name 5 factors which may cause hepatocyte damage

Answer 9

1. Alcohol
2. Hep B, C, D
3. Excess iron in the liver
4. Autoimmune liver disease
5. Obesity

Question 10

Name two other locations besides the esophagus where portal-systemic anastomoses exist.

Incl the signs seen on examination for each

Answer 10

1. The rectum: rectal varicies ➞ hemorrhoids
2. The umbilicus: if blood can’t drain into the liver, more drains through the systemic circulation into the abdomen ➞ caput medusae

Question 11

What is the ‘streamline flow of the Portal vein theory’?

How does this help predict the origin of a tumour based on it’s location in the liver?

Answer 11

Theory states that blood from the SMV and IMV mix incompletely in the PV, resulting in disproportionate distribution within the liver lobes.

The SMV distributes mainly to the right lobe compared to the IMV, which supplies both hemilivers similarly.

Therefore we can predict that tumours on the R lobe of the liver came through the SMV and originated from a midgut structure.

Question 12

What other vein does the superior mesenteric vein combine with to form the portal vein?

Answer 12

Splenic vein

Question 13

Into which regions does the spleen tend to enlarge in splenomegaly?

Answer 13

From the Left hypochondrium towards the R iliac fossa (downwards and medial)

Question 14

Why is splenic rupture so dangeorus?

Answer 14

The spleen is highly vascularised and hence a rupture will lead to large blood loss

Question 15

Pancreatic Cancer often invades the _______ of the pancreas. Invasion can compress and obstruct the _______ and/or _______.

If cancer invades posteriorly, it can invade/block portal venous confluence of ______ and ______.

Answer 15

head, bile duct, ampulla of vater, splenic, SMV

Question 16

What can occur due to blockage of the common bile duct (ie. cancer in the pancreatic head)

Name 3 associated symptoms which may be seen

Answer 16

Blockage of the CBD and/or ampulla of vater can lead to erosion of bile pigment into the liver and boodstream.

Symptoms: jaundice, pale stools, dark urine (excessive bile being excreted

Question 17

The small Intestine is the longest part of the GI tract and extends from the ______ region of stomach to the ______ junction

It consists of the _______, _______, _______

Answer 17

pyloric, ileocecal, duodenum, Jejunum, Ileum

Question 18

The duodenum is C-shaped and located adjacent to the _________. It is connected to the liver by the _______ and can be divided in _____ parts.

Answer 18

head of the pancreas, hepatoduodenal ligament, 4

Question 19

What connects the duodenum to the liver?

Answer 19

The Hepatoduodenal ligament

Question 20

What are the 4 parts of the duodenum shown on the image below

Answer 20

Question 21

Which region of the duodenum are duodenal ulcers most likely to occur

Answer 21

The Superior part ➞ “Duodenal cap”

Question 22

Which section of the duodenum are the major and minor duodenal papillas located? What is the function of these

Answer 22

The descending part

papillas are where the biliary and pancreatic juices enter the dunodenum

Question 23

Which part of the duodenum do the SMA and SMV cross anteriorly?

Answer 23

The inferior part

Question 24

What is the suspensory ligament of Treitz and where is it located?

Answer 24

Ligament attaching the 4th part of the duodenum to the diaphragm above

Located in the ascending part of the duodenum

Question 25

Give 2 potential consequences of an aneurysm of the SMA and explain each

Answer 25

1) Entrapment of the L. renal vein (drains the L. gonad) between the AA and SMA. Results in a back-pressure tracing to the testis ➞ scrotal varicosities ➞ variocoele
2) Obstruction the duodenum, may be treated by ligation of the ligament of treitz

Question 26

Intussusception is when the ______ portion of the intestine telescopes INTO a ______ segment of the intestinal tube.

It commonly involves the ______ and the ______ colon at the ______ junction.

Answer 26

proximal, distal, ileum, proximal, ileocolic

Question 27

Label the image of the large intestine

Answer 27

Question 28

Name 3 symptoms/consequences of intussusception

Answer 28

1) abdominal cramping
2) currant jelly stools ➞ dark red and mucoid
3) bowel perforation due to necrosis ➞ blood supply from SMA (ileocolic branches)

Question 29

What is diverticulosis, whic part of the intestine is it most common in and which age group is most suseptible?

Answer 29

Multiple false out-pocketings of mucosa of colon, common occurs in the sigmoid colon and affects middle aged/elderly people → if inflammation occurs can lead to diverticulitis

Question 30

The large Intestine recieves blood supply from distal ____ and _____

The procedure __________ can be used to visualize polyps and perform minor procedures such as biopsies.

MOST tumours of the colon occur in the ______ colon and the _______.

Answer 30

SMA, IMA, Colonoscopy, Sigmoid, Rectum

Question 31

What is the significance of the ‘apple core sign’ on an X-ray?

Answer 31

Associated with constriction of the lumen of the colon by a stenosing annular colorectal carcinoma

Question 32

What additional role does the Liver play in a Foetus

Answer 32

Haematopoiesis

Question 33

What is the dual blood supply of the liver

Answer 33

1) Proper Hepatic artery (25%)
2) Portal Vein (75%)

Question 34

What is the purpose of tethering of mesenteries?

Answer 34

Tethering of the mesenteries (incl the transverse mesocolon) limits some movement of fluid

BUT… sometimes fluid exudates can travel in paracolic gutters and track down to the pelvic cavity or sub phrenic spaces where abcesses may form