Anatomy 3 (lecture 5)

Question 1

what are the functions of the large intestine?

Answer 1

Defence (commensal bacteria)
Absorption (H2O and electrolytes)
Excretion

Question 2

How is the caecum related to the peritoneum?

Answer 2

Intraperitoneal (quite mobile)

Question 3

How is the ascending colon related to the peritoneum?

Answer 3

Secondarily retroperitoneal

Question 4

What does secondarily retroperitoneal mean?

Answer 4

It originally was originally intraperitoneal (embryology)

Question 5

What is the transverse colon in relation to the peritoneum?

Answer 5

intraperitoneal - highly mobile (has own mesentery)

Question 6

Descending colon in relation to the peritoneum?

Answer 6

Secondarily retroperitoneal

Question 7

What is the sigmoid colon in relation to the peritoneum?

Answer 7

Intraperiotneal - quite mobile as it has its own mesentery

Question 8

Where are the 2 paracolic gutters?

Answer 8

Between the lateral edge of the ascending and descending colon and abdominal wall (called left and right paracolic gutters)

Question 9

What are the paracolic gutters part of?

Answer 9

The greater sac of the peritoneal cavity

Question 10

Where do the teniae coli run from and to?

Answer 10

From the caecum to the distal end of the sigmoid colon

Question 11

What are the haustra?

Answer 11

Small pouches in the colon formed from the tonically contracted teniae coli

Question 12

What causes darker blobs on a plain AXR?

Answer 12

Air

Question 13

What does faeces appear like in the rectum on a plain AXR?

Answer 13

“Mottled” - mixture of air and faeces

Question 14

In what part of the abdomen do the caecum and appendix lie?

Answer 14

The right iliac fossa

Question 15

What is the opening of the ileum into the caecum called?

Answer 15

The ileocaecal orifice

Question 16

What is the opening of the appendix into the caecum called?

Answer 16

Appendiceal orifice

Question 17

How is the appendix most often located in comparison to the caecum?

Answer 17

Retrocaecal (64%)
Position can vary causing a variation in the symptoms people present with e.g. men can present with testicular pain due to extending down to the pelvis and irritating structures

Question 18

On what part of the caecum is the appendiceal orifice mostly always on?
What does this correspond to?

Answer 18

The posteromedial wall
McBurney’s point (1/3 of the way between right Anterior Superior Iliac Spine and the umbilicus)
Usually the point of maximum tenderness in appendicitis

Question 19

In what part of the abdomen does the sigmoid colon lie?

Answer 19

left iliac fossa

Question 20

What is the mesentery of the sigmoid colon called

Answer 20

Sigmoid mesocolon (gives it a considerable degree of movement)

Question 21

Volvolus?

Answer 21

Abnormal twisting of a part of the GI tract

Question 22

What is it called when the sigmoid colon twists around itself?
What does this result in?
What is the bowel at risk of if it is left untreated?

Answer 22

Sigmoid volvulus
Bowel obstruction
Infarction

Question 23

Where does the abdominal aorta lie in relation to the IVC?

Answer 23

Left of the IVC

Question 24

What are the 3 midline branches of the abdominal aorta and what does each supply?

Answer 24

Celiac trunk (foregut organs)
Superior mesenteric artery (midgut organs)
Inferior mesenteric artery (hindgut organs)

Question 25

What do the lateral branches of the abdominal aorta supply? (3)

Answer 25

``` Body wall (posterolateral) Kidneys/ adrenal glands Gonads (ovaries/ testicles) ```

Question 26

What does the abdominal aorta bifurcate into? | What does this further bifurcate into?

Answer 26

Common iliacs | Internal and external iliacs

Question 27

See diagrams on superior mesenteric artery and inferior mesenteric artery

Answer 27

...

Question 28

What is the predominant artery which anastomoses between the branches of the SMA and IMA?

Answer 28

Marginal artery of Drummond

Question 29

What do arterial anastomoses between the SMA and IMA help to do?

Answer 29

Prevent intestinal ischaemia by providing a collateral route by which blood can travel

Question 30

Where does the hindgut extend to?

Answer 30

The proximal half of the nail canal (the pectinate line)

Question 31

What is the name of the line that divides the 2 half of the anal canal?

Answer 31

The pectinate line

Question 32

What is the remainder of the GI tract (from the pectinate line) supplied arterially by?

Answer 32

The internal iliac artery (middle and inferior rectal arteries branch from this) - there is a degree of anastomoses between these vessels

Question 33

What are oesophageal varies

Answer 33

Abnormal dilated veins with thin walls which therefore have the potential to rupture

Question 34

What often leads to the formation of varcies?

Answer 34

Pathology affecting the portal venous system

Question 35

What 2 vessels does the systemic venous system drain blood into?

Answer 35

Superior or inferior vena cava

Question 36

What does the inferior vena drain blood from in terms of the liver

Answer 36

Hepatic veins

Question 37

What are the 3 vessels that drain blood into the hepatic portal vein

Answer 37

Splenic vein (foregut) Superior mesenteric vein (midgut) Inferior mesenteric vein (hindgut)

Question 38

Are there any valves in the collateral veins of the portal systemic anastomoses

Answer 38

No - blood can flow either way

Question 39

Where are the 3 portal systemic anastomoses?

Answer 39

Skin around umbilicus Distal end of oesophagus Rectum/ anal canal

Question 40

At the portal systemic anastomoses at the distal end of the oesophagus, where does the most inferior part and the most superior part drain

Answer 40

``` Superior = azygous Inferior = hepatic portal vein ``` Anastomoses form between these

Question 41

At the portal systemic anastomoses at the rectum/ anal canal, where does the most inferior part and the most superior part drain

Answer 41

Rectum and superior anal canal drains to inferior mesenteric vein Most inferior part of the GI tract drains to the internal iliac veins Anastomoses form between these

Question 42

Portal-systemic anastomoses - skin around umbilicus?

Answer 42

``` normally the ligamentum teres remains closed throughout adult life and blood flows from the skin around the umbilicus via inferior epigastric veins to the IVC ```

Question 43

Where does the superior rectal vein branch from?

Answer 43

Inferior mesenteric vein

Question 44

Where does the middle rectal vein branch from?

Answer 44

The internal iliac vein

Question 45

Where does the inferior rectal vein branch from?

Answer 45

The internal iliac vein

Question 46

Name for increased blood pressure in the portal veins? | What is this caused by?

Answer 46

Portal hypertension | Liver pathology e.g. cirrhosis

Question 47

What happens during portal hypertension to cause varicose?

Answer 47

Blood is diverted through the collateral veins back to the systemic venous system These collateral veins consequently have a much larger volume of blood through them than they are used to so dilate becoming varicose

Question 48

Clinical presentation of portal hypertension? (3)

Answer 48

Oesophageal varices Caput medusae Rectal varcies