Colon

Question 1

Parts of the colon

Answer 1

Ascending
Transverse
Descending
Sigmoid

Question 2

Length of the colon

Answer 2

150cm

Question 3

Course of the ascending colon

Answer 3

Ascends from the caecum to the right lobe of the liver and turns 90 degrees to move horizontally at the right colic flexure

Question 4

Where is the right colic flexure

Answer 4

Deep to ribs 9-10 and inferior part of the liver

Question 5

What kind of peritoneal structures are the ascending and descending colon

Answer 5

Secondary retroperitoneal

Question 6

What percentage of people have a short mesentery of the ascending colon

Answer 6

25%

Question 7

Where is the right paracolic gutter

Answer 7

Between the lateral aspect of the ascending colon and the posterolateral abdominal wall

Question 8

What’s the longest part of the colon

Answer 8

Transverse colon

Question 9

What’s the most mobile part of the colon

Answer 9

Transverse colon

Question 10

Where does the transverse colon run from and to

Answer 10

Right colic flexure to the left colic flexure

Question 11

Differences between the left (splenic) and right (hepatic) colic flexures

Answer 11

Left colic flexure is more superior, more acute and less mobile than the right colic flexure

Question 12

What does the phrenicocolic ligament attach

Answer 12

Diaphragm to the left colic flexure

Question 13

Where is the left colic flexure

Answer 13

Anterior to the left kidney

Question 14

Vertebral level of the transverse colon

Answer 14

L3 (level of the umbilicus) but in tall thin people it may extend into the pelvis

Question 15

Where does the sigmoid colon run from and to

Answer 15

From the left iliac fossa to the S3 vertebra

Question 16

Shape of the sigmoid colon

Answer 16

S-shaped

Question 17

What signals the rectosigmoid junction

Answer 17

Termination of the teniae coli

Question 18

Length of the sigmoid colon

Answer 18

Variable but roughly 40cm

Question 19

Describe the sigmoid mesocolon and the consequence of this

Answer 19

Very long therefore the sigmoid colon is very mobile which can lead to volvulus of the sigmoid colon

Question 20

What kind of peritoneal structure is the transverse colon

Answer 20

Intraperitoneal

Question 21

Where is the transverse mesocolon

Answer 21

Fused with the posterior wall of the lesser sac and loops down inferior to the level of the iliac crests

Question 22

Where is the root of transverse mesocolon

What is it continuous with

Answer 22

Inferior border of the pancreas

Continuous with the posterior parietal peritoneum

Question 23

What percentage of people have a short mesentery of the descending colon

Answer 23

33%

Question 24

Where does the descending colon run from and to

Answer 24

From the left colic flexure to the left iliac fossa

Question 25

What does the descending colon cross

Answer 25

Lateral border of the left kidney

Question 26

Where is the left paracolic gutter

Answer 26

Between the lateral aspect of the descending colon and the posterolateral abdominal wall

Question 27

Describe the root of the sigmoid mesocolon

Answer 27

Inverted V-shaped attachment

Question 28

Arterial supply of the ascending colon and right colic flexure

Answer 28

Abdominal aorta -> SMA -> ileocolic artery | Abdominal aorta -> SMA -> right colic artery

Question 29

What do the ileocolic and right colic arteries anastomose with and what does this form

Answer 29

They anastomose with the right branch of the middle colic artery to form a series of arcades that forms the marginal artery (continuous arterial channel round the large intestine)

Question 30

Venous drainage of the ascending colon and right colic flexure

Answer 30

Ileocolic and right colic veins which drain into the SMV and subsequently the hepatic portal vein

Question 31

Link the embryological origin of the transverse colon to its blood supply

Answer 31

Derived from midgut and hindgut so is supplied by the superior and inferior mesenteric vessels

Question 32

Arterial supply of the transverse colon

Answer 32

Abdominal aorta -> SMA -> middle colic artery Abdominal aorta -> SMA -> right colic artery Abdominal aorta -> IMA -> left colic artery

Question 33

Venous drainage of the transverse colon

Answer 33

Middle colic vein which drains into the SMV and subsequently the hepatic portal vein

Question 34

Arterial supply of the descending colon

Answer 34

Abdominal aorta -> IMA -> left colic artery

Question 35

Arterial supply of the sigmoid colon

Answer 35

Abdominal aorta -> IMA -> sigmoid arteries

Question 36

Venous drainage of the descending colon

Answer 36

Left colic vein which drains into the IMV

Question 37

Venous drainage of the sigmoid colon

Answer 37

Sigmoid veins which drain into the IMV

Question 38

Where do vasa recta arise from

Answer 38

The marginal artery (of Drummond)

Question 39

Innervation of ascending colon and proximal 2/3 transverse colon

Answer 39

Superior mesenteric plexus

Question 40

Innervation of distal 1/3 transverse colon, descending colon and sigmoid colon

Answer 40

Inferior mesenteric plexus Sympathetic - lumbar splanchnic nerves Parasympathetic - pelvic splanchnic nerves

Question 41

What does lymph from the ascending and transverse colon drain into

Answer 41

Superior mesenteric nodes

Question 42

What does lymph from the descending and sigmoid colon drain into

Answer 42

Inferior mesenteric nodes

Question 43

What do the superior and inferior mesenteric nodes drain into

Answer 43

Intestinal lymph trunks and subsequently the cisterna chyli where it ultimately empties into the thoracic duct