Lecture 5 - hindgut

Question 1

What does the descending colon connect and where is it located?

Answer 1

It connects the sigmoid colon to the trasnverse colon. It is mostly found in the left quadrants.

Question 2

What part of the colon is the descending colon?

Answer 2

The fourth part

Question 3

The descending colon is …..peritoneal?

Answer 3

secondarily retroperitoneal

Question 4

What is located laterally to the descending colon?

Answer 4

The left paracolic gutter

Question 5

What is the left colic felxure closely related to?

Answer 5

The spleen

Question 6

The descending colon is typically …… than the ascending colon

Answer 6

longer

Question 7

What is the arterial supply to the descending colon?

Answer 7

The left colic artery which branches from the inferior mesenteric artery.

Question 8

What part of the colon is the sigmoid colon?

Answer 8

It is the 5th part.

Question 9

What does the sigmoid colon connect?

Answer 9

It connects the descending colon and the rectum.

Question 10

Where is the sigmoid colon located?

Answer 10

It is lcoated in the left lower quadrant.

Question 11

The sigmoid colon extends from where to where usually?

Answer 11

It usually extends from the iliac fossa to approximately L3 level.

Question 12

What is the sigmoid colon usually charecterised by ? (shape)

Answer 12

S shape loop

Question 13

The sigmoid colon is a ….peritoneal organ

Answer 13

intraperitoneal

Question 14

Where do the teniae coli terminate at?

Answer 14

At the rectosigmoid junction

Question 15

What is the arterial supply to the sigmoid colon?

Answer 15

Sigmoid arteries are direct branches of the inferior mesenteric artery.

Question 16

Where does the rectum lie?

Answer 16

It lies between the sigmoid colon and the anal canal.

Question 17

What are the internal fearures of the rectum?

Answer 17

There are rectal folds

Question 18

What are the external features of the rectum?

Answer 18

There are no haustra, no teniae coli, and no ommental appendices

Question 19

The rectum is ……peritoneal in the proximal part and ……peritoneal in the distal part.

Answer 19

Primarily retroperitoneal

Infraperitoneal

Question 20

What is the anal canal continous with?

Answer 20

It is continous with the rectum at the pelvic diaphragm where it makes a 90 degree bend.

Question 21

90 degree bend that the anal canal does at the pelvic diaphragm is called?

Answer 21

It is called the anorectal flexure

Question 22

What is the anal canal divided into?

Answer 22

It is divided into an upper (Between the pectinate line and the anorectal junction) and lower (between the pectinate line and the anus) part by the pectinate line.

Question 23

What do the anal columns contain?
Where are the anal valves?
What are the anal sinuses?

Answer 23

1. ) Series of longitudinal ridges that contain the superior rectal vessels.
2. ) located at the inferior ends of the anal columns
3. ) small recesses that are superior to the anal valves. They secrete mucus during defacation

Question 24

What innervates the anal canal?

Answer 24

Superior part of the anal canal - visceral inenrvation

Inferior part of the anal canal - somatic innervation

Question 25

Arterial supply to the rectum and the anal canal?

Answer 25

Superior rectal artery - it is a terminal branch from the inferior mesenteric artery Middle rectal artery - comes from the internal iliac artery Distal rectal artery - comes from the internal pudendal artery Essentially, above the pectinate line the supply comes from the inferior mesenteric artery and below the pectinate line it coems from the internal iliac artery.

Question 26

What is the venous drainage of the distal large intestine?

Answer 26

Above the pectinate line it is the portal venous systema dn below the pectinate line it is the systematic venous system.

Question 27

What are the lymphatics of the distal large intestine?

Answer 27

Descending, sigmoid and proximal rectum - inferior mesenteric lymph nodes Distal rectum above the pectinate line - internal iliac lymp nodes Distal rectum below the pectinate line - superficial inguinal lymph nodes

Question 28

Innervation of the rectum

Answer 28

Above pectinate - parasympathetic - pelvic splanchnic nerves Above the pectinate - sympathetic - lumbar splanchnic nerves Below the pectiante - somatic innervation by the inferior rectal nerves.

Question 29

What anastomosis occurs between the foregut and midgut and the midgut and the hindgut?

Answer 29

1. ) sueprior and inferior pancreaticoduodenal anterior arteries 2. ) Middle and left colic arteries

Question 30

What is the marginal artery of drummond?

Answer 30

It is a term used to describe the arteries supplying the midgut and hindgut. They collectively form a continous cycle along the inenr border of the large colon.

Question 31

What is the commonest area of colonic ischemia and with what arteries?

Answer 31

The middle and left colic artery may not meet and this causes it. It happens at the splenic flexure known as the sudeck's point.

Question 32

What is the direction of peritoneal fluid when supine vs inclined?

Answer 32

supine - two sites where inflammatory exudate tends to collect is the hepatorenal recess adn teh right posterior subphrenic recess. inclined - collects in pelvic cavity where there is a slow absorption of toxins.

Question 33

What is dialysis?

Answer 33

It is the seperation of particles in a liquid on the basis of differences in their ability to pass through a membrane.

Question 34

What is peritoneal dialysis?

Answer 34

The peritoneum is a semipermeable membrane which allows for a relatively rapid absorption of solutions. In renal failure, a dilute sterile solution can be introduced to the side of the peritoneal cavity on one side. Excess water and soluble waste products like urea can be transferred from the blood vessels. This allows for the dilute solution and waste products to be drained out og the peritoneal cavity from the other side.

Question 35

What is the pringle maneuver?

Answer 35

Technique to minimise blood loss during hepatic surgery by clamping the blood vessels entering the liver. Specifically, the portal triad travels within the hepatoduodenal ligament and this is clamped to minimise bleeding. If patient still bleeding after clamping, then the haemorrhage is from somewhere else like the hepatic veins or the IVC.

Question 36

Omental bursa herniation?

Answer 36

When part of the GI (usually loop of the small intestine) tract can pass through the omental foramen and become twisted and strangulated inside the lesser sac. It is a rare type of internal abdominal hernia and some predisposing factors: large omental foramen, redundant or mobile mesentery, elongated right liver, defect in the lesser omentum.

Question 37

What are the boundries of teh omental foramen?

Answer 37

Anterior: Hepatoduodenal ligament Posterior: IVC and the right crus of the diaphragm Superior: Caudate lobe of the liver Inferior: 1st part of the duodenum

Question 38

What are peritoneal adhesions:

Answer 38

Fibrous bands that form abnormal connections: Like the visceral peritoneum attching to an adjacent organ or to the parietal peritoneum. Occurs as a result of damage to the peritoneal surface and so the body tries to heal it and covers it in sticky fibrin to assist the healing process. This limits the movement of viscera and leads to intestinal obstruction and chronic pain. Laparotomy - surgical incision into the abdominal cavity prior to major surgery and adhesiotomy - surgical seperation of adhesions.

Question 39

What are the volvulus of the sigmoid colon?

Answer 39

It is a condition involving the twisting and rotation of the mobile loops of intestinal tract. Associated usually with teh sigmoid colon. Results in obstruction of the lumen and lead to constipation and ischemia of the intestine. If it is left untreated then it may lead to necrosis and an immovable collection of compressed faeces may develop.