Chapter 12 Flashcards by Deborah Karp

What is the main purpose of the colon?

Absorption of water and sodium

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Tx of uncomplicated diverticulitis

IV abx and bowel rest

If complicated and/or recurrent: elective colectomy

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What is the leading cause of LBO?

Cancer

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Tx for ulcerative colitis

Can do total protocolectomy with end end ileostomy or total protocolectomy with ileal pouch and anastamosis

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What is the most common form of intestinal volvulus?

Sigmoid volvulus

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Tx of sigmoid volvulus

Detorsion via sigmoidoscopy followed by bowel prep and elective sigmoidoscopy with primary anastamosis or Hartmann’s procedure

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What is the initial tx for anal squamous cell carcinoma?

Chemoradiation

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What are the most common tumors of the appendix?

Carcinoid tumors

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Where is the foregut? What is it supplied by?

End at 2nd portion of the duodenum

Supplied by the celiac artery

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Where is the midgut?

What is it supplied by?

Duodenal ampulla to the 1st 2/3 of the transverse colon

Supplied by the SMA

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Where is the hindgut?

What is it supplied by?

Distal transverse and descending colon as well as proximal rectum
Supplied by IMA

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What supplies the distal rectum?

Internal iliac artery

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How is the anus formed?

By an invagination of the ectomdermal anal pit and fuses with the distal rectum at the dentate line

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What are the four major layers of the colon?

Mucosa (columnar epithelium)
Submucosa (muscularis mucosa)
Muscularis propria
Serosa

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Muscularis propria

Inner circular
Outer longitudinal smooth muscle: forms three bands
-Teniae coli (run along the colon and converge distally at the top of the rectum)
-Produce haustra, which give the colon its appearance on X-ray

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How long is the colon?

150 cm

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Where does the colon start and end?

Starts at the cecum in the RLQ

Ends 15 cm from anal verge

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How long is the rectum?

12-15 cm long

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Where does the rectum start and end?

Peritoneal reflection to the dentate line (2-4 cm from anal verge)

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What is the most common site of rupture secondary to obstruction or pseudo-obstruction?

Cecum

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What is the average diameter of the cecum?

7.5 cm

Most capacious area of the colon

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Where is the appendix?

Arises from base of cecum-within 2-3 cm of ileocecal valve

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What is the MC position of the appendix tip?

Posterior to the cecum

Position of the right colon

Posterior surface is retroperitoneal and lies near the duodenum

Position of transverse colon | What is it suspended by?

Completely intraperitoneal | Suspended by broad mesentery

Which flexure is higher than the other?

Splenic flexure is higher than the hepatic flexure

Greater omentum

Gastrocolic ligament (coming from greater curve of the stomach) fuses to peritoneal covering of the colon

Position of the descending colon

Partially retroperitoneal and fixed

Position of the sigmoid colon

Intraperitoneal

How is the upper 1/3 of the rectum covered?

Anteriorly and laterally by peritoneum

How is the middle 1/3 of the rectum covered?

By peritoneum anteriorly

Position of the distal rectum

Entirely extra-peritoneal

How is the posterior rectum covered?

By fascia propria

What preserves the lymphatics during rectal cancer surgery?

Dissecting in the plan between the fascia propria of the rectum and sacrum

How many rectal ligaments are formed by the fascia propria? | What do they contain?

2 | Middle rectal artery and mixed autonomic nerves

If the mixed autonomic nerves in the two rectal ligaments of the fascia propria get injured, what can result?

Erectile of bladder dysfunction

Where does the anus begin?

At dentate line | Surgically begins at the level of the pelvic floor muscle

What do the mucosa at the dentate line form?

Longitudinal folds called columns of Morgagni

If the bases of the columns of Morgagni are infected, what is the result?

Anorectal abscesses and fistulas

How is fecal continence controlled?

By muscles of the pelvic floor

What are the muscles of the pelvic floor that control fecal continence called?

Levator ani Internal anal sphincter (involuntary smooth muscle) External anal sphincter (striated voluntary muscle)

What supplies the right colon and first 2/3 of transverse via its branches (middle, right, and ileocolic)?

The SMA via the aorta

Where does the ileocolic branch of the SMA go to?

Appendiceal artery

What is the blood supply of the proximal and middle thirds of the transverse colon?

The middle colic artery branch of the SMA which branches off into left and right branches

What is usually ligated during a right colectomy?

Right branch of the middle colic branch of the SMA

What supplies the left colon and proximal rectum?

The IMA via the aorta, which branches into the left colic, sigmoidal, and superior rectal vessels

What supplies the distal rectum and anus?

The middle rectal artery via the internal iliac AND | the inferior rectal artery via the internal pudendal artery

Marginal artery of Drummond

Series of arterial arcades running along the mesenteric border of the entire colon

Arc of Rioland

Connects proximal SMA and IMA

What is at risk for ischemia because it lies between the SMA and IMA?

Splenic flexure

Venous drainage

IMV leads to splenic vein, joins with SMV to form the portal vein Distal rectum and anus drained by the middle and inferior rectal veins, goes to internal iliac veins, goes to systemic circulation

Lymphatics

Follows blood supply | Tumor in mid/distal rectum goes to iliac nodal basins

Sympathetic innervation

Runs along blood vessels Thoracic roots supply SMA distribution Lumbar roots supply IMA distribution Sacral roots supply tpelvic floor, distal rectum and anus

When can occur if the hypogastric nerve is injured when ligating the IMA?

Ejaculatory dysfunction

Parasympathetic innervation

Right vagus innervates the right and transverse colon | Sacral roots innervate left colon and rectum