[4] Colon, Rectum, and Anus Flashcards
[For Test Notes]
- Embryology is included although not taught
What signals your body to defecate?
Gastrocolic Reflex: Distension of the stomach leads to distension of the colon
How do you diagnose a diverticula?
Colonoscopy
Define: Volvulus
Twisting portion of the intestine around itself or a stalk of mesentery causing an obstruction
What part of the colon is most usually involved in a Volvulus?
Sigmoid Colon
Why is the Sigmoid Colon easily twisted?
The base is very narrow as compared to the other parts, making it easy to twist
Define: Small Bowel and Colon Intussusception
Condition in which one section of the bowel tunnels into an adjoining section
Internal Diameter of Cecum
7.5-8.5cm
Internal Diameter of Sigmoid
2.5cm
[Retroperitoneal or Intraperitoneal]
Ascending Colon
Transverse Colon
Sigmoid Colon
Descending Colon
- Retro
- Intra
- Intra
- Retro
Why does appendicitis cause epigastric pain?
Referred pain due to shared afferent T10 dermatomes
Where would you cut open for an appendectomy?
Point of Maximal Abdominal Tenderness
Where is McBurney’s Point?
1/3 of the way from ASIS -> Umbilicus
Usual location of the appendix
Retrocecal
Define: Psoas Sign
Pain elicited with passive extension of the hip
Define: Obturator Sign
Pain elicited with passive flexion and internal rotation of the hip
Define: Romsey Sign
Pressure on the left lower quadrant causes pain on the right lower quadrant
What happens if you cut the Inferior Mesenteric Artery?
What about the Superior Mesenteric Artery?
IMA: little ischemia, but it will survive
SMA: The small intestine will die
How many degrees is the Anorectal Angle?
When sitting?
During Sphincter Squeeze?
102 Degrees
119 Degrees
81 Degrees
What muscle contracts to make defecation harder?
Puborectalis
What do you use to differentiate external and internal hemorrhoids?
Dentate Line
Fate of the Foregut
o Esophagus o Stomach o Pancreas o Duodenum o Liver o Biliary Ducts
Fate of the Midgut
o Small intestine distal to the bile duct o Cecum o Appendix o Ascending colon o Most of the transeverse colon
Fate of the Hindgut
o Distal transverse colon
o Descending and Sigmoid colon
o Rectum
Describe: Taenia Coli
- Three flat bands of smooth muscle separated at 120 degree intervals along the wall of the colon
- Incomplete outer longitudinal muscle layer
Define: Haustrae
Outpouchings in the colon wall between taenia coli
Function: Epiploic Appendages
- 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
Entrance of the Ileum into the Cecum
Ileocecal Valve
What supplies blood to the Cecum?
Ileocolic Artery
What supplies blood to the Appendix?
Appendicular Artery
Where the colon turns downward to become descending colon
Splenic Flexure (Left Colic Flexure)
Most mobile part of the colon
Transverse Colon
Where colon turns left
Hepatic Flexure (Right Colic Flexure)
What supplies the colon from cecum to splenic flexure?
Superior Mesenteric Artery
Branches of the Superior Mesenteric Artery (3)
Ileocolic
Right Colic
Middle Colic
What supplies the Ascending Colon?
Ileocolic and Right Colic Arteries
What supplies the Transverse Colon?
Middle Colic Artery
What supplies the Descending and Sigmoid Colon?
Inferior Mesentery Artery via the Left Colic and Sigmoid Arteries
What do you call the anastomosis of arteries in the colon?
Marginal Artery of Drummond
