[4] Colon, Rectum, and Anus

Question 1

[For Test Notes]

Answer 1

• Embryology is included although not taught

Question 2

What signals your body to defecate?

Answer 2

Gastrocolic Reflex: Distension of the stomach leads to distension of the colon

Question 3

How do you diagnose a diverticula?

Answer 3

Colonoscopy

Question 4

Define: Volvulus

Answer 4

Twisting portion of the intestine around itself or a stalk of mesentery causing an obstruction

Question 5

What part of the colon is most usually involved in a Volvulus?

Answer 5

Sigmoid Colon

Question 6

Why is the Sigmoid Colon easily twisted?

Answer 6

The base is very narrow as compared to the other parts, making it easy to twist

Question 7

Define: Small Bowel and Colon Intussusception

Answer 7

Condition in which one section of the bowel tunnels into an adjoining section

Question 8

Internal Diameter of Cecum

Answer 8

7.5-8.5cm

Question 9

Internal Diameter of Sigmoid

Answer 9

2.5cm

Question 10

[Retroperitoneal or Intraperitoneal]

Ascending Colon
Transverse Colon
Sigmoid Colon
Descending Colon

Answer 10

1. Retro
2. Intra
3. Intra
4. Retro

Question 11

Why does appendicitis cause epigastric pain?

Answer 11

Referred pain due to shared afferent T10 dermatomes

Question 12

Where would you cut open for an appendectomy?

Answer 12

Point of Maximal Abdominal Tenderness

Question 13

Where is McBurney’s Point?

Answer 13

1/3 of the way from ASIS -> Umbilicus

Question 14

Usual location of the appendix

Answer 14

Retrocecal

Question 15

Define: Psoas Sign

Answer 15

Pain elicited with passive extension of the hip

Question 16

Define: Obturator Sign

Answer 16

Pain elicited with passive flexion and internal rotation of the hip

Question 17

Define: Romsey Sign

Answer 17

Pressure on the left lower quadrant causes pain on the right lower quadrant

Question 18

What happens if you cut the Inferior Mesenteric Artery?

What about the Superior Mesenteric Artery?

Answer 18

IMA: little ischemia, but it will survive
SMA: The small intestine will die

Question 19

How many degrees is the Anorectal Angle?
When sitting?
During Sphincter Squeeze?

Answer 19

102 Degrees
119 Degrees
81 Degrees

Question 20

What muscle contracts to make defecation harder?

Answer 20

Puborectalis

Question 21

What do you use to differentiate external and internal hemorrhoids?

Answer 21

Dentate Line

Question 22

Fate of the Foregut

Answer 22

o Esophagus
o Stomach
o Pancreas
o Duodenum
o Liver
o Biliary Ducts

Question 23

Fate of the Midgut

Answer 23

o Small intestine distal to the bile duct 
o Cecum
o Appendix
o Ascending colon
o Most of the transeverse colon

Question 24

Fate of the Hindgut

Answer 24

o Distal transverse colon
o Descending and Sigmoid colon
o Rectum

Question 25

Describe: Taenia Coli

Answer 25

- Three flat bands of smooth muscle separated at 120 degree intervals along the wall of the colon - Incomplete outer longitudinal muscle layer

Question 26

Define: Haustrae

Answer 26

Outpouchings in the colon wall between taenia coli

Question 27

Function: Epiploic Appendages

Answer 27

- Protect and cushion the colon, like a small omentum - Blood depository during colonic vessel contraction - Fat storage, role in absorption and immune response - In surgery, protection from suture lines and close perforations - Seal perforations

Question 28

Entrance of the Ileum into the Cecum

Answer 28

Ileocecal Valve

Question 29

What supplies blood to the Cecum?

Answer 29

Ileocolic Artery

Question 30

What supplies blood to the Appendix?

Answer 30

Appendicular Artery

Question 31

Where the colon turns downward to become descending colon

Answer 31

Splenic Flexure (Left Colic Flexure)

Question 32

Most mobile part of the colon

Answer 32

Transverse Colon

Question 33

Where colon turns left

Answer 33

Hepatic Flexure (Right Colic Flexure)

Question 34

What supplies the colon from cecum to splenic flexure?

Answer 34

Superior Mesenteric Artery

Question 35

Branches of the Superior Mesenteric Artery (3)

Answer 35

Ileocolic Right Colic Middle Colic

Question 36

What supplies the Ascending Colon?

Answer 36

Ileocolic and Right Colic Arteries

Question 37

What supplies the Transverse Colon?

Answer 37

Middle Colic Artery

Question 38

What supplies the Descending and Sigmoid Colon?

Answer 38

Inferior Mesentery Artery via the Left Colic and Sigmoid Arteries

Question 39

What do you call the anastomosis of arteries in the colon?

Answer 39

Marginal Artery of Drummond