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Colon and Rectum > Anatomy of colon, rectum and anus > Flashcards

Anatomy of colon, rectum and anus Flashcards

1
Q

Which of the following statements is false?

A. Splenic flexure is located higher than the hepatic flexure

B. Cecum has the maximum diameter in the entire colon

C. Rectosigmoid junction has the smallest diameter in the entire colon

D. Ileocecal valve contains valve like mechanism

A

Ans D -

Diameter of the cecum is approx 7.5cm

Diameter of the Rectosigmoid junction is approx 2.5cm

Ileocecal valve is considered a misnomer by a number of authors, and the actual valve mechanism is located in the termninal ileum.

ICV is a continuation of circular and longitudinal muscles of ileum and prevents reflux. Frequently incompetent.

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2
Q

Which of the following statements is false?

A. The colon is longer in women

B. The difference in length is due to longer transverse colon

C. Transverse colon has a higher likelihood of lying below the level of umbilicus in women than in men

D. Colonoscopy is easier in women

A

Ans D -

The colon is approx 10cm longer in women, mostly due to a longer transverse colon which has a higher propensity to lie below the level of the umbilicus in women. This makes colonoscopy difficult in women.

Colonscopy is also more difficult in the western population as compared to the asian population.

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3
Q

which of the following is not a taenia coli

A. Taenia ommentalis
B. Taenia Libera
C. Taenia Mesocolica
D. Taenia saginata

A

Ans D -

Taenia coli are longtiduinal muscles of the colon that are extending from the tip of cecum to the rectosigmoid. They are 6mm wide, and they are shorter in length than the colon, this produces the puckering of colon or haustra formation.

Taenia saginata is tapeworm.

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4
Q

During the herniation of the gut in the embryonic life, which of the following is last portion of colon to return to the abdomen?

A. Hepatic flexure
B. Cecum
C. Transverse colon
D. Ascending colon

A

Ans B -

Cecum is the last portion of the colon to return to the abdomen

Initially the cecum resides in the RUQ

With lengthening of the colon it moves towards the RLQ.

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5
Q

Dentate line in the anal canal is embryologically represented by?

A. Urorectal Septum
B. Anal Pit
C. Cloacal membrane
D. Cloaca

A

Ans C -

Hindgut and Allantois merge distally and empty into a dilated collection chamber called - CLOACA.

6th to 12th week - cloaca is divided sagitally by urorectal septum into ventral and dorsal segments

Further enfolding of lateral walls l/t caudal advancement of the distal segment.

Simultaneously involution of the adjacent ectodermal derived body wall called Proctodeum or anal pit occurs.

Proctodeum and dorsal cloaca fuse to become the cloacal membrane. This membrane is obliterated via apoptosis - forming the Dentate line that represents the anatomic division of the hindgut/endoderm (Proximal 2/3) and the proctoderm (Distal 1/3) of the anal canal.

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6
Q

Length of the entire GIT -

A. 6m
B. 7m
C. 9m
D. 10m

A

Ans C -

mouth to anus the length of the intestine is 9m.

The large intestine is approx 165cm long.

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7
Q

which of the following is the main function of the Ileocecal valve?

A. preventing reflux from the colon into the ileum

B. Avoiding bacterial overgrowth in the terminal ileum

C. delaying transit from the ileum into the colon

D. Both A and B

A

Ans C -

The function of the ileocecal valve is to delay transit from ileum to cecum and not necessarily to prevent reflux of contents from the cecum to the ileum.

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8
Q

What is the approximate length of the colon -

A. 100cm
B. 150cm
C. 200cm
D. 250cm

A

Ans - B.

150cm (average) - 120-200cm.

Max diameter - cecum 7.5cm
min diameter - rectosigmoid 2.5cm.

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9
Q

Which of the following refers to the Bloodless fold of Treves?

A. Superior Ileocecal recess.
B. Inferior Ileocecal fold
C. Superior ileocecal fold
D. Inferior ileocecal recess

A

ANs B -

Superior ileocecal fold - extends anteriorly as a mesentric appendage and in this fold runs the anterior cecal artery.
Covers the superior ileocecal recess.

Inferior ileocecal fold - connects the antimesentric aspect of terminal ileum to the mesentriolum of appendix. Does not contain blood vessels and hence called Bloodless fold of Treves.
Inferior ileocecal recess lies posterior and inferior to this fold.

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10
Q

Gerlach’s valve is found in -

A. Rectum
B. Junction of cystic duct and Gall bladder neck.
C. Appendiceal orifice
D. base of meckel’s diverticulum

A

Ans C -

A mucosal fold inconsistently covers the appendix and this is called the Gerlach’s valve.

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11
Q

Which of the following is False regarding endoscopic view of the cecum

A. The lowest haustrum corresponds to cecal fundus.

B. Visualisation of appendiceal orifice which appears as fish mouth is suggestive of completion of endoscopy

C. Ileal orifice has ileocolic and ileocecal lips.

D. none of the above

A

Ans B -

Lowest haustrum corresponds to the cecal fundus on endoscopy - this is also the location of the appendiceal orifice and a sign of completion of colonoscopy.

A mucosal fold can be inconsistently seen covering the appendix - Gerlach’s valve.

3rd landmark on endoscopy is the ileal orifice - fish mouth or pouting lips - containing two lips - Ileocolic lip (Superior) and ileocecal lip (Inferior)

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12
Q

Average length of the appendix is -

A. 3cm
B. 5cm
C. 9cm
D. 12cm

A

Ans C -

Average length of the appendix is 9cm.

Shackleford - 2-20cm.
Sabiston - 5-35cm.
Bailey - 7.5-10cm

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13
Q

Most common location of the appendix is -

A. Preileal
B. Sub-cecal
C. Post-ileal
D. Pelvic
E. Paracecal
A

Ans D

The most common position is

  • Retrocecal (74%)
  • Pelvic (21%)

Least common -
Bailey - post ileal 0.5%.
Shackleford/Sabiston - subhepatic.

Shackle - retroperitoneal position 7-10%.

Commonest position is retrocecal intraperitoneal - due to the rotation produced by the continued growth of cecum.

In 25% individuals - rotation does not occur –> pelvic, subcecal or paracecal position.

If cecum does not descend to the normal position - appendix can be found near the gall bladder - subhepatic.

In intestinal malrotation appendix can be found in the left iliac fossa.

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14
Q

Which of the following statements is false -

A. Position of the base of the appendix corresponds to the junction of the three taeniae coli.

B. The position of the base of the appendix is constant.

C. Lumen of the appendix is the widest in adolescents which increases their likelihood of developing fecoliths.

D. Mucosa of the appendix is colonic type with abundant lymphoid tissue in submucosa

A

Ans C -

Position of the base of the appendix is constant - at the junction of the three taenia coli.
It is located below and behind the ICV.

Lumen of the appendix is widest in infants and gradually narrows througout life.

Mucosa of the appendix is colonic type with many folds - columnar epithelium containing goblet cells.
Abundant lymphoid tissue is present in the submucosa.

Crypts are present in the mucosa of the appendix and at the base of these crypts lie the Argentaffin cells or Kulchitsky cells - which can give rise of Carcinoid.

Appendix corresponds to the undeveloped distal end of large cecum found in many lower animals.

At birth the appendix is short and broad at its junction, but the typical tubular structure is attained at 2 years due to differential growth of cecum.

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15
Q

Which of the following statements is false -

A. Bloodless fold of Treves can be used to locate the appendix intraop

B. Tracing the anterior taenia coli

C. Appendiceal artery is the branch of right colic arter

D. Base of the appendix is supplied by anterior and posterior cecal arteries

A

Ans C -

Appendix can be located intraop by using the bloodless fold of Treves or tracing the taenia coli especially the anterior taenia coli or Taenai Ommentalis.

Appendiceal artery, which is an end-artery, is a branch of lower division of ileocecal artery which in turn is a branch of SMA.

Base of the appendix is additionally supplied by the anterior and posterior cecal arteries.

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16
Q

Most frequent site of carcinoid tumors is -

A. Appendix
B. Ileum
C. Jejunum
D. Stomach

A

Ans A -

Appendix is the most frequent site of carcinoid - Bailey and Love 27e Pg 1300.

17
Q

All of the following are posterior relations of the ascending colon except -

A. Ilioinguinal and illiohypogastric nerves
B. Inferior-medial aspect of the right kidney
C. Lateral cutaneous nerve of thigh
D. Right gondal artery and vein

A

Ans B -

Posterior relations -

  • Ilioinguinal nerve
  • iliohypogastric nerve
  • Inferolateral aspect of Right kidney
  • 4th lumbar vein
  • Gerota’s fascia
  • Lateral cutaneous nerve of thigh
  • Right Goandal artery and vein
  • Right ureter.
18
Q

Jackson membrane is seen in

A. Ascending colon
B. Descneding colon
C. Transverse colon
D. Cecum

A

Ans A -

Jackson membrane is a tenuous adhesion from the right abdominal wall to the anterior-taenia of ascending colon. Rarely present.

19
Q

which of the following is a false statement -
A. Hepatic flexure moves with respiration about 2.5cm-7.5cm.

B. Hepatic flexure is located superior to splenic flexure

C. Hepatic flexure can be connected to the duodenum via a duodenocolic ligament

D. Hepatic flexure lies immediately above the second part of duodenum

A

Ans B -

Hepatic flexure is located inferior to splenic flexure.

Rest all are true statements.

Splenic flexure is connected to the diaphragm via the phrenico-colic ligaments. (10th and 11th ribs)

20
Q

Root of the the transverse mesocolon - all of the following except -

A. Hilum of the right kidney
B. second part of duodenum
C. Pancreas
D. Hilum of the left kidney

A

Ans A -

Root of transverse mesocolon runs along -

  • Lower pole of right kidney
  • second part of duodenum
  • pancreas
  • hilum of the left kidney.

Ligament of Trietz is just inferior to the root of the transverse mesocolon.

21
Q

Toldt’s fascia holds which of the following to the posterior peritoneum

A. Ascending colon
B. Cecum
C. Descending colon
D. Transverse colon

A

Ans C - descending colon is 25cm in length and fixed on the posterior peritoneum by the told’t fascia.

Descending colon is narrow and more deeply placed compared to the ascending colon.

22
Q

Which of the following statements is false -

A. Sigmoid mesocolon is inverted V shaped with the apex of the V located at the Bifurcation of the left common iliac.

B. length of the sigmoid colon is approximately 40cm.

C. Mesocolon is greatest in length at the tips, and narrowest at the apex.

D. long narrow mesentry of the sigmoid predisposes for volvulus

A

Ans C -

Sigmoid mesocolon is inverted V shaped, with the apex at the Bifurcation of the Left common iliac, whereas the tips are at the Left iliac fossa, and 2nd or 3rd sacral space.

Diameter of sigmoid colon decreases along its length.

There are 3 part of the sigmoid colon, it is the most proximal descending part that remains in contact with the left pelvic wall.

The mesocolon is greatest in length at the apex , and therefore the sigmoid colon is fixed at its junctions.

Long convuluted sigmoid predisposes to constipation.

Long narrow sigmoid mesocolon predisposes to volvulus.

23
Q

All of the following are distinguishing features of the rectosigmoid junction except -

A. Continuous longitudinal muscle coat
B. No appendices epiploicae
C. No true mesentry
D. Complete peritoneal investment

A

Ans D -

6 distinguishing feature of the rectosigmoid are -

  • Continuous longitudinal muscle coat
  • no appendices epiploicae
  • no true mesentry
  • absence of complete peritoneal investment
  • endoscopy shows smooth flat mucosa of rectum transitioning into the sigmoid mucosa with folds.
24
Q

Which of the following statements is false -

A. Sigmoid is narrower in males
B. sigmoid is longer in females
C. Transverse colon is longer in females
D. Sigmoid is wider in females

A

Ans B -

Sigmoid is longer and narrower in males.

25
Q

Mercedez Benz Sign refers to

A. Convergence of 3 taenia coli on endoscopy
B. Gas fissuring seen in a gallstone on X ray
C. Both And B

A

Ans C

26
Q

Which of the following is not true regarding the endoscopic view of colon

A. Bow & Arrow sign refers to the appendiceal orifice
B. Pouting lips sign refers to the ileocecal valve
C. Hepatic flexure has bluish tinge due to the indentation of liver
D. sigmoid colon is triangular in shape

A

Ans D -

Ileocecal valve -

  • Pouting lips lying transversely
  • Mucosa appears velvety
  • Bile staining is present
  • Moves rhythmically and movement is accentuated by inflation and deflation.

Mercedez Benz Sign - covergence of taenia

Appendiceal orifice is curvilinear with the Bow and Arrow sign suggesting that the curve points to the ICV.

Hepatic flexure has bluish tinge due to the indentation of liver. Also, once past the flexure the best way to advance is to shorten the endoscope while applying suction - this is called paradoxical advancement

Transverse colon is triangular in shape due to the attachment of peritoneum at 3 points - Gastrocolic ommentum, Transverse mesocolon, Greater ommentum.

Splenic flexure also has a bluish tinge due to the presence of spleen.

Sigmoid-descending colon junction is the most fdifficult part to negotiate.

27
Q

SMA arises at the level of

A. T12
B. L1
C. L2
D. L3

A

ans B -

SMA L1 level
IMA L3 level

28
Q

Which of the following statements is true -

A. Ileocolic artery gives off ileal branch and colic branch at the ICJ.

B. Anterior cecal artery is the larger branch and present in 100% individuals.

C. Posterior Cecal artery is absent in nearly 90% individuals and supplies the medial, posterior and lateral walls of the cecum.

D. Appendicular artery arises from the Posterior cecal artery

A

Ans B -

Ileocolic artery gives off the ileal and colic branches at the ICJ, and then goes on to divide into the -

  • Anterior cecal artery - smaller branch, supplying the anterior cecal wall and present in 100%.
  • Posterior cecal artery - larger branch supplying the posterior, medial and lateral walls of the cecum and absent in 10% cases. Also gives rise to the appendiceal artery.
29
Q

Most common anomaly of the right colic artery is -

A. Arises from SMA
B. Arises from Middle colic artery
C. Absence of right colic artery
D. Arises from ileo-colic artery

A

Ans - C -

Right colic artery arises from the right side of the root of the SMA, and then divides into the ascending and descending branches. Most common anomaly of the right colic artery is . -

  • absence in 26%
  • MCA origin in 19%.
30
Q

which of the following is the most constant branch of the SMA -

A. Ileocolic artery
B. Middle colic artery
C. Right Colic artery
D. Inferior Pancreticoduodenal artery

A

Ans A -

Ileocolic artery is the most constant branch of SMA>

31
Q

Middle colic artery may be absent in -

A. 1-5%
B. 5-20%
C. 15-30%
D. 20-40%

A

ans B -

Middle colic artery is absent in 4-20% of the cases.

32
Q

Which of the following points has the most tenuous blood supply in colon -

A. Griffith’s point
B. Sudeck’s Point
C. Junction of proximal 2/3 and distal one third of transverse colon
D. Hepatic flexure

A

Ans A -

Griffith’s point also known as the “Watershed” area in the colon has the most tenuous blood supply - and can show features of ischemic colitis in case of sudden occlusion of the IMA. It is the weakest link in the margin artery - junction of Left branch of Middle colic artery and ascending branch of LCA in the region of splenic flexure.

The marginal artery of Drummond made up of branches from IMA and SMA. Vessels arising from the marginal artery of drummond are called VASA RECTA. At the splenic flexure the Vasa Recta are the most further apart (Approx 2cm) and have few collaterals.

Vasa recta divide into smaller branches which supply the 2/3 of the circumference of the colon on the mesenteric colon, whereas the longer branches supply the 1/3 of the antimesenteric circumference of the colon.

Sudeck’s point
refers to the inconsistent and small anastomosis formed between the last sigmoid branch of the IMA and a branch of the superior rectal artery. This point also called the Sudeck’s critical point due to the tenuous vascular supply at this point.

33
Q

Which of the following statements is false -

A. Arc of Riolan connects the proximal SMA with the proximal IMA.

B. in case of IMA stenosis the flow through the Arc of Riolan is retrograde.

C. After high ligation, the marginal artery adequately supplies the descending colon but not the sigmoid colon.

D. Middle colic artery can sometimes originate from the IMA trunk

A

Ans B

Arc of Riolan is an inconstant artery that connects the proximal superior mesenteric artery or one of its primary branches to the proximal inferior mesenteric artery or one of its primary branches. It is classically described as connecting the middle colic branch of the SMA with the left colic branch of the IMA. It forms a short loop that runs close to the root of the mesentery.

Arc of Riolan becomes prominent in case of occlusion of either the IMA or SMA.

Arc of Riolan is also known as the Central Anastomotic mesentric artery or Meandering artery of Moskowitz.

In case of IMA stenosis - flow through Arc of Riolan is forwards, whereas in case of SMA stenosis the flow through the Arc of Riolan is retrograde.

After high ligation of IMA - marginal artery remains adequate to supply the transverse and descending colon but not the sigmoid and the supply of the sigmoid decreases by nearly 50%.

Middle colic artery can sometimes originate from the IMA trunk and even from the Celiac artery.

34
Q

Which of the following is correctly matched -

A. Epicolic nodes - Appendices Epiploicae
B. Paracolic ndoes - ascending branch of Left colic artery
C. Intermediate nodes - IMA
D. Central nodes - Para-aortic

A

Ans C -

Epicolic nodes - are located in subserosal and epiploid appendages.

Paracolic nodes - behind the peritoneum on the mesenteric side of colon, along smaller branches of LCA, MCA, RCA and Ileo-colic artery.

Intermediate nodes - are along named vessels - LCA, MCA, RCA and Ileocolic artery.

Central nodes - SMA, IMA and Para-aortic.

35
Q

IMA divides into three trunks is what type of IMA -

A. Type I
B. Type II
C. Type III
D. Type IV

A

ANS - D

A. Type I - Left colic artery + Rectosigmoid trunk
B. Type II - colosigmoid trunk + Superior rectal artery
C. Type III - Colosigmoid trunk + Rectosigmoid trunk
D. Type IV - three branches - LCA, Sigmoid trunk, Sup. Rectal artery.

36
Q

IMA divides into three trunks is what type of IMA -

A. Type I
B. Type II
C. Type III
D. Type IV

A

ANS - D

A. Type I - Left colic artery + Rectosigmoid trunk
B. Type II - colosigmoid trunk + Superior rectal artery
C. Type III - Colosigmoid trunk + Rectosigmoid trunk
D. Type IV - three branches - LCA, Sigmoid trunk, Sup. Rectal artery.

Colon and Rectum (1 decks)

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