GIT anat learning from mcq

Question 1

Describe the inncervation of rectus abdominis

Answer 1

It is innervated by the thoraco-abdominal nerves (anterior rami of T6 – T12 spinal nerves), which are continuations of the lower IC nerves in the abdomen (the lower IC nerves are no longer known as intercostal as they do not run in the subcostal groove of the ribs).

Question 2

A newborn that is found to have a transverse colon passing posterior to the duodenum & superior mesentery artery is likely to have:
a. faulty development of the foregut
b. lack of rotation of the midgut
c. a volvulus of the hindgut
d. failure of herniation
e. clockwise rotation of the midgut

Answer 2

(E) Clockwise rotation of the midgut
In normal development of the gut, the midgut undergoes a 270 degrees counter-clockwise rotation, resulting in the transverse colon anterior to the duodenum and the superior mesenteric artery. However, in rare cases, where the midgut undergoes a reversed (clockwise) rotation, the transverse colon will pass posterior to the duodenum and the artery. Compared to non-rotation (midgut did not undergo rotation) and malrotation (90 degree rotation without the subsequent 180 degree rotation in later stages), this condition is rarer.

Question 3

The (common) bile duct:
a. is formed by union of the right and left hepatic ducts
b. is about 2cm long
c. runs posterior to the portal vein in the free border of the lesser omentum
d. terminates in the 2nd part of the duodenum
e. passes anterior to the accessory pancreatic duct

Answer 3

(D) Terminates in the 2nd part of the duodenum
The common bile duct is formed from the fusion of the common hepatic duct (from the liver) and the cystic duct (from the gallbladder). The common bile duct empties into the 2nd part of the duodenum together with the pancreatic duct through the duodenal papilla, regulated by the Sphincter of Oddi. FYI, the bile duct passes posterior to the accessory pancreatic duct.

Question 4

A stab wound in the lower left chest posteriorly is least likely to affect the:
a. Diaphragm
b. small intestine
c. spleen
d. kidney
e. splenic flexure of the colon

Answer 4

(B) Small intestines
A stab wound in the lower left chest posteriorly would most likely damage (most superficial to deep) the left hemidiaphragm, left kidney, spleen. Since the splenic flexure of the colon is in close proximity (inferior to the spleen), the flexure would mostly be affected as well compared to the small intestines which are more medial.

Question 5

The lesser sac is least likely to be located:
a. to the right of the epiploic foramen
b. in the greater omentum
c. posterior to the stomach
d. anterior to the pancreas
e. posterior to the lesser omentum

Answer 5

(A) To the right of the epiploic foramen
The lesser sac (also known as the omental bursa) is found posterior to the stomach and anterior to the pancreas, which is retroperitoneal. The lesser sac is continuous with the cavity in the greater omentum and fluid may flow into the cavity of the greater omentm from the lesser sac. To the right of the epiploic foramen, one will find the right subhepatic space, the hepatorenal pouch (otherwise known as the Morison’s pouch) and inferiorly, the right paracolic gutter. These are all compartments of the greater sac of the peritoneal cavity

Question 6

Segmental arteries to the kidneys:
a. originate from the aorta
b. supply the suprarenal glands
c. have poor anastomosis
d. supply only the renal cortex
e. are usually 3 in number

Answer 6

(C) Have poor anastomosis
The renal artery divides closer to the hilum of the kidney into 5 segmental arteries: apical segmental artery, anterior superior segmental artery, anterior inferior segmental artery, inferior segmental artery and posterior segmental artery. These arteries do not anastomose significantly with each other, so the area supplied by each segmental artery is an independent, resectable unit.

Question 7

Radiographic investigation at the level transpyloric plane is unlikely to yield which of the following structures?
a. Spleen
b. Left kidney
c. Fundus of the stomach
d. Duodenum
e. End of the spinal cord

Answer 7

(C) Fundus of the stomach
The transpyloric plane lies at the vertebral level of L1, demarcating the level of the pylorus of the stomach when a person is in the supine position. The fundus of the stomach is superior to the plane and will not be present in the radiographic investigation. The fundus lies posterior to the left 6th rib in the plane of the midclavicular line, while the transpyloric plane transects the 8th costal cartilage

Question 8

Which of the following is true of gut development
a. axis of rotation is IM artery
b. reverse (clockwise) rotation can result in the duodenum lying anterior to the transverse colon
c. fixation only involves the large gut
d. herniation occurs in the fetal period

Answer 8

(B) Reverse rotation can result in the duodenum lying anterior to the transverse colon
In normal development of the gut, the midgut undergoes a 270 degrees counter-clockwise rotation, resulting in the transverse colon anterior to the duodenum and the superior mesenteric artery. However, in rare cases, where the midgut undergoes a reversed (clockwise) rotation, the transverse colon will pass posterior to the duodenum and the artery. Compared to non-rotation (midgut did not undergo rotation) and malrotation (90 degree rotation without the subsequent 180 degree rotation in later stages), this condition is rarer.

Question 9

The sigmoid colon
a. is controlled by vagus
b. has villi for absorption of food
c. is retroperitoneal
d. terminates at the pelvic brim
e. has venous drainage into splenic veins

Answer 9

13. (E) Has venous drainage into splenic veins
    a. The sigmoid colon has innervation from the pelvic splanchnic nerves (which primarily innervates the parts of the colon derived from the hindgut)
    b. The sigmoid colon primarily serves to store the feces till the body is ready for defecation, and no absorption occurs in this part of the colon. In which case, it is unlikely that the sigmoid colon has villi for food absorption.
    c. The sigmoid colon is intraperitoneal and a mobile portion of the colon, continuing from the descending colon. Other parts of the colon which are intraperitoneal include the cecum and the transverse colon.
    d. The sigmoid colon terminates at the third sacral (S3) vertebra, where it joins the rectum. The pelvic brim is bordered by posteriorly the sacral promontory; the ala of the sacrum, the arcuate line on the inner surface of the ilium, the pectineal line, the pubic crest (on left and right sides); and anteriorly the pubic symphysis. With this in mind, the sigmoid colon terminates inferior to the pelvic brim.
    e. The sigmoid colon has venous drainage into the inferior mesenteric vein (which drains the hindgut), which drains into the splenic vein (which will eventually form the portal vein as the superior mesenteric vein joins up behind the neck of the pancreas). Hence, it is correct to say that the sigmoid colon has venous drainage into the splenic veins.

Question 10

Upper anal canal has the following feature that is different from lower anal canal
a. lymphatic drainage to inguinal nodes
b. pain mediated by pudendal nerve
c. veins drain into portal systemic system
d. an internal sphincter made of striated muscle
e. a lining of stratified squamous epithelium

Answer 10

(C) Veins drain into portal systemic system
The upper and lower anal canal can be distinguished using the pectinate line which is an irregular line formed by the comb-shaped limit of the anal valves. Due to differences in embryological development, the two portions have distinct differences in terms of venous drainage, arterial supply, innervation and lymphatic drainage. The upper anal canal (superior to the pectinate line) is supplied by the superior rectal artery and drained by the internal rectal venous plexus (draining chiefly into the superior rectal vein, which is a tributary of the portal systemic system). Lymph from this region is drained deeply into the internal iliac lymph nodes. The nerve supply to the upper anal canal is primarily visceral innervation from the inferior hypogastric plexus.
On the other hand, the lower canal (inferior to the pectinate line) is supplied by the two inferior rectal arteries and drained by the internal rectal venous plexus (but draining chiefly into the inferior rectal veins, which is a tributary of the caval venous system). Lymph from this region is drained superficially into the superficial inguinal lymph nodes. The nerve supply to the lower anal canal is primarily somatic innervation derived from the inferior anal nerves (branches of the pudendal nerve).

Question 11

The blood supply to the stomach is unlikely to show
a. the short gastric arteries supplying the greater curvature
b. the right gastric artery supplying the lesser curvature
c. veins draining into the portal vein
d. Rich vascular anastomosis in the muscularis externa
e. the gastroduodenal artery passing behind the pyloroduodenal junction.

Answer 11

(D) Rich vascular anastomosis in the muscularis externa
a. The short gastric arteries are branches of the splenic artery, which supply the superior part of the greater curvature of the stomach and more importantly, the fundus of the stomach.
b. The right gastric artery is a branch of the common hepatic artery, which rims along the lesser curvature of the stomach to anastomose with the left gastric artery. Together they supply the lesser curvature of the stomach.
c. The veins of the stomach do indeed drain eventually into the portal vein, though different veins may take different routes: (a) the short gastric veins and left gastro-omental (gastroepiploic) veins drain into the splenic vein which drains into the portal vein (b) the right gastric vein drains directly into the portal vein while (c) the right gastro-omental (gastroepiploic) vein drains into the superior mesenteric vein, which later drains into the portal vein.
d. By elimination of the other options, one will arrive at this option. Logically reasoning it out, blood vessels usually run in the submucosal layer. It would make sense that the vascular anastomosis likely occur at the submucosal layer rather than the muscular layer. Also, gastric anastomosis are known to occur between the right and left gastric arteries extensively in the serosal layer.

Question 12

Which of the following nerves passes through the superficial inguinal ring?
a. iliohypogastric nerve
b. obturator nerve
c. lateral femoral cutaneous nerve
d. ilioinguinal nerve
e. pudendal nerve

Answer 12

(D) Ilioinguinal nerve
The ilioinguinal nerve passes through the superficial inguinal ring, through the inguinal canal. Other structures which pass through the superficial inguinal ring include the testicular vessels

Question 13

Regarding the anatomy of the inguinal canal, all of the following statements are true about it EXCEPT:
a. its floor is predominately formed by the inguinal ligament
b. its deep ring is located just lateral to the inferior epigastric artery
c. its roof is formed by arching fibers of the internal oblique and transversus muscles
d. its deep ring is formed by peritoneum
e. its superficial ring is formed by the aponeurosis of the external oblique muscle

Answer 13

(D) Its deep ring is formed by peritoneum
The deep inguinal ring is formed from an evagination in the transversalis fascia that forms an opening. The other statements are true: the floor of the inguinal canal is formed from the inguinal ligament; the roof formed from the arching fibres of the internal oblique and transversus abdominis muscles; the anterior wall formed by the aponeurosis of the external oblique muscle and the posterior wall by the transversalis fascia. The superficial ring is formed from the fibers of the external oblique aponeurosis

Question 14

Which of the following arteries is used to characterize an inguinal hernia as direct or indirect?
a. obturator
b. deep external pudendal
c. femoral
d. superficial circuinflex iliac
e. inferior epigastric

Answer 14

(E) Inferior Epigastric
A direct inguinal hernia occurs medial to the inferior epigastric artery, while an indirect inguinal hernia occurs lateral to the artery, potentially through the inguinal canal (and into the scrotal sac for males).

Question 15

The “porta hepatis” of the liver transmits all of the following EXCEPT the:
a. hepatic arteries
b. hepatic ducts
c. autonomic nerves from the celiac plexus
d. portal vein
e. hepatic veins

Answer 15

(E) Hepatic Veins
The “porta hepatis” of the liver transmits the portal triad, consisting of the bile duct, hepatic arteries and the portal vein, through the hepatoduodenal ligament (free margin of the lesser omentum). The autonomic nerves from the celiac plexus (sympathetic nerves) follow the course of the blood vessels. Hepatic veins are found on the superior surface of the liver, formed by the union of collecting veins that in turn drain the central veins of the hepatic parenchyma. They drain into the IVC near the diaphragm, on the superior portion of the liver.

Question 16

The posterior boundary of the epiploic foramen (of Winslow) is the:
a. caudate lobe of the liver
b. first part of the duodenum
c. portal vein
d. common bile duct
e. inferior vena cava

Answer 16

(E) Inferior vena cava
The epiploic foramen is superiorly bounded by the caudate lobe of the liver, inferiorly bounded by the first and superior part of the duodenum, anteriorly bounded by the hepatoduodenal ligament which conveys the portal triad (portal vein, common bile duct and hepatic arteries) and finally posteriorly bounded by the inferior vena cava and the right crus of the diaphragm, which are both retroperitoneal

Question 17

The common bile duct and major pancreatic duct join to form the:
a. hepatic duct
b. common hepatic duct
c. cystic duct
d. cistema chyli
e. ampulla of Vater

Answer 17

E) Ampulla of Vater
The common hepatic duct is formed from the right and left hepatic duct and later goes on to form the common bile duct with the joining of the cystic duct, which drains bile from the gallbladder. The common bile duct, together with the major pancreatic duct, subsequently drains into the 2nd part of the duodenum as the ampulla of Vater, or the hepato-pancreatic ampulla, through the duodenal papillae

Question 18

When removing the spleen, a surgeon must be careful not to cut one of the splenic artery branches, the:
a. superior mesenteric
b. left gastric
c. left gastroepiploic
d. superior pancreaticoduodenal
e. left rena

Answer 18

(C) Left gastroepiploic artery
The left gastroepiploic artery (also known as the left gastro-omental artery) is a major branch of the splenic artery which supplies the left side of the greater curvature of the stomach. It anastomoses with the right gastroepiploic artery which is a branch of the gastroduodenal artery.

Question 19

Which nerve is identified by its position on the anterior surface of the psoas major muscle?
a. Femoral
b. ilioinguinal
c. genitofemoral
d. obturator
e. lateral femoral cutaneous

Answer 19

C) Genitofemoral nerve
The genitofemoral nerve pierces the psoas major and runs inferiorly on its anterior surface, deep to the psoas fascia. The femoral nerve emerges from the lateral border of the psoas major muscle and passes deep to the inguinal ligament to the anterior thigh. The ilioinguinal nerve enters the abdomen posterior to the medial arcuate ligament and passes inferolaterally, anterior to the quadratus lumborum. The ilioinguinal nerve is also found in the inguinal canal. The obturator nerve emerges from the medial border of the psoas major and passes into the lesser pelvis, passing through the obturator foramen into the thigh. The lateral femoral cutaneous nerve runs inferolaterally on the iliacus and enters the thigh deep to the inguinal ligament

Question 20

Lesser sac
a. lies posterior to the pancreas
b. Anterior to stomach
c. May extend into the area enclosed by greater omentum
d. Develops mostly from ventral mesogastrium

Answer 20

C) May extend into the area enclosed by the greater omentum
The lesser sac lies posterior to the stomach and anterior to the pancreas, which is retroperitoneal (and hence fixed). Fluid from the lesser sac can flow into the inferior recess bounded by the double-layered peritoneal folds of the greater omentum (typically in the infant because in the adult, the two peritoneal folds of the greater omentum fuses)

Question 21

Where does the gastric anastomoses occur? (two answers depending on what kind of anastamoses)
a. Serosa
b. Submucosa
c. Mucosa
d. inner longitdunal layer
e. outer longitudinal layer

Answer 21

A) Serosa
The major vessels which supply the stomach (both the lesser and greater curvatures included) form extensive anastomoses on the serosal surface. The right and left gastroepiploic arteries and the left and right gastric arteries anastomose freely along the greater and lesser curvatures respectively. Anastomosis also occurs between the left gastric artery and the short gastric arteries to supply the fundus of the stomach. While networks still do occur in the other layers (especially so in the submucosa to ensure to a rich blood supply to the mucosal layer), the gastric anastomoses primarily and most extensively occur in the serosa.

Question 22

The lesser omentum is LIKELY to
a. Extend inferiorly as far as the transverse colon
b. separate the lesser sac from the right paracolic gutter
c. attach superiorly to the porta hepatis and the fissure for the ligamentum venosum
d. form the posterior boundary of the lesser sac

Answer 22

(C) Attached superiorly to the porta hepatis and the fissure for the ligamentum venosum
a. The lesser omentum would at most extend inferiorly to the lesser curvature of the stomach, which is its inferior attachment. It is attached superiorly to the porta hepatis (the free margin of the lesser omentum and the hepatoduodenal ligament) and the fissure for the ligamentum venosum (remnants of the ductus venosus).
b. Technically, it does… but a more appropriate relation would be that the lesser omentum separates the lesser sac from the greater sac, which the right paracolic gutter is a component of.
c. As described in option a, the lesser omentum is attached superiorly to the fissure for the ligamentum venosum on the visceral surface of the liver.
d. The lesser omentum is likely to form the anterior boundary of the lesser sac together with the stomach; posteriorly, it would be bounded by the peritoneum anteriorly covering the retroperitoneal pancreas, and superoposteriorly, the posterior aspect of the coronary ligaments of the liver.

Question 23

A MRI at the transpyloric plane is unlikely to show which structure?
a. Stomach
b. Liver
c. Right kidney
d. Pancreas
e. Third part of the duodenum

Answer 23

E. The transpyloric plane transects the 8th costal cartilage and the L1 vertebra when the person is supine, and most importantly, lies at the level of the pylorus of the stomach. Hence, to be more specific, a MRI at the transpyloric plane will likely show the pyloric section of the stomach, the pancreas which resides inferior and posterior to the pyloric region of the stomach, the liver and the superior pole of the right kidney. The third part of the duodenum resides inferior to the pancreas, which make it unlikely that it will show up on an MRI at the transpyloric plane.

Question 24

Pain from stomach at left epigastrium is a result of afferent impulses
a. from parietal peritoneum
b. reaching superior mesenteric plexus
c. travel up lumbar splanchnics
d. reaching thoracic sympathetic chain
e. entering spinal cord at L1

Answer 24

d

Question 25

Which of the following are not tributaries of the portal vein?
a. Superior mesenteric vein
b. Inferior mesenteric vein
c. Splenic vein
d. Superior rectal vein
e. Inferior rectal vein

Answer 25

E) Inferior rectal vein
The inferior rectal vein is a caval tributary. It drains into the internal pudendal vein, which drains into the internal iliac vein and finally into the inferior vena cava. Hence, it is not a part of the portal systemic circulation. The superior rectal vein drains into the inferior mesenteric vein, which joins with the splenic vein. After which, the splenic vein fuses with the superior mesenteric vein to form the portal vein which is conveyed to the liver via the hepatoduodenal ligament with the other components of the portal triad.

Question 26

The rotation of the stomach to give the anterior and posterior vagal trunks looking from the caudal end (from inferiorly) is:
90° rotation of the oesophagus in the clockwise direction
90° rotation of the oesophagus in the anticlockwise direction
90° rotation of the stomach in the clockwise direction
90° rotation of the stomach in the anticlockwise direction
90° rotation of the midgut in the clockwise direction

Answer 26

D) 90° rotation of the stomach in the anticlockwise direction
Conceptually, it is important to understand that in the thorax the vagus nerve runs as the left and right vagus nerves. After which, it enters the enteric plexuses present in the oesophagus and emerges again as the anterior and posterior vagus nerves. Most of the fibres which run in the left vagus nerve continue to travel in the anterior vagus nerve while fibres of the right vagus nerve travel in the posterior vagus nerve. The change in orientation is due to the rotation of the stomach and using a simple diagram, it is evident that the stomach undergoes a 90° rotation in the anticlockwise direction to give such a transition in the orientation of the vagus nerve.

Question 27

Fluid moving from the lesser sac to the greater sac would first pass through the
a. Rectovesical pouch
b. Hepatorenal pouch
c. Left paracolic gutter
d. Right paracolic gutter
e. Left subdiaphragmatic space

Answer 27

B) Hepatorenal pouch
Fluid from the lesser sac flows into the greater sac through the epiploic foramen (also known as the foramen of Winslow), into the subhepatic space inferior to the visceral surface of the liver. The hepatorenal pouch (also known as the Morison’s pouch) is the posterosuperior extension of the subhepatic space lying between the right part of the visceral surface of the liver and the right kidney and suprarenal gland. In the supine position, fluid from the omental bursa would likely drain into the hepatorenal recess due to action of gravity. The rectovesical pouch, left and right paracolic gutter are further down in the abdominal cavity and hence are unlikely to be sites where the fluid first drains.

Question 28

The developmental cause for the superior mesenteric artery to be in front of the transverse colon and behind the duodenum is
a. Clockwise rotation of midgut
b. Inadequate fixation of cranial part of midgut
c. Abnormal rotation of the midgut artery
d. Faulty rotation of the hindgut
e. Counterclockwise rotation of the midgut

Answer 28

A) Clockwise rotation of midgut
In normal development of the gut, the midgut undergoes a 270 degrees counter-clockwise rotation, resulting in the transverse colon anterior to the duodenum and the superior mesenteric artery. However, in rare cases, where the midgut undergoes a reversed (clockwise) rotation, the transverse colon will pass posterior to the duodenum and the artery. Compared to non-rotation (midgut did not undergo rotation) and malrotation (90 degree rotation without the subsequent 180 degree rotation in later stages), this condition is rarer.

Question 29

An indirect inguinal hernia is UNLIKELY to pass through
a. Lateral to the inferior epigastric vessels
b. Deep to the conjoint tendon
c. Deep to the external oblique aponeurosis
d. Deep to the internal oblique muscle
e. Scrotal sac

Answer 29

B) Deep to the conjoint tendon
An indirect inguinal hernia usually results from the protrusion of bowel through the deep inguinal ring, lateral to the inferior epigastric artery, into the inguinal canal and if severe enough, enters the scrotal sac in males through the superficial ring. The inguinal canal is anteriorly bounded by the aponeurosis of external oblique muscle, inferiorly bounded by the inguinal canal, and posteriorly bounded by the conjoint tendon in the medial third and the transversalis fascia. The roof of the inguinal canal is formed by the overarching fibres of the internal oblique and transversus abdominis muscles. If the hernia were to occur within the inguinal canal, it now makes sense that it passes through deep to both the aponeurosis of the external oblique and the internal oblique muscle. However, a hernia deep to the conjoint tendon would most likely lead to direct inguinal hernia, as the bowels now push through the weakened conjoint tendon, into the superficial inguinal ring directly anterior to the conjoint tendon.
*The conjoint tendon is formed by a fusion of the aponeurosis of the internal oblique muscle and the transversus abdominis muscle, inserted into the pectineal line and pubic crest.

Question 30

Obstructive jaundice is least caused by the obstruction of the
a. Right hepatic duct
b. Cystic duct
c. Common bile duct
d. Common hepatic duct
e. Duodenal papilla

Answer 30

B) Cystic duct
The first option may seem very tempting because ultimately, there is the left hepatic duct which drains bile from the left lobe of the liver but we have to consider (1) obstructive jaundice and (2) the function of the gallbladder. First, obstructive jaundice is a result of accumulation of bilirubin due to obstruction of the bile canaliculi or any of the ducts which conduct bile into the duodenum. Second, the gallbladder functions to concentrate the bile and does not produce bile. Therefore, keeping these in mind, obstruction of the right hepatic duct, common hepatic duct, common bile duct and the duodenal papilla would almost certainly result in obstructive jaundice but obstruction of the cystic duct will not as likely cause obstructive jaundice; but rather result in the loss of ability to concentrate bile (which might later go on to affect digestion of fats).

Question 31

Which of the following regarding peritoneal spaces is false?
a. Lesser sac in front of body of pancreas
b. Pouch of Douglas is between rectum and uterus in female
c. Hepatorenal pouch is part of greater sac
d. Right paracolic gutter is lateral to descending colon
e. Peritoneum on ivc forms posterior border of foramen of Winslow

Answer 31

D) Right paracolic gutter is lateral to descending colon
The right paracolic gutter is lateral to the ascending colon on the right side, and the left paracolic gutter is lateral of the descending colon on the left.