Mar2 M2-GI Embryology In the Trenches Part 2

Question 1

(EXAM) foregut, midgut, hindgut where to where + their artery

Answer 1

foregut = pharynx to DJ junction (celiac trunk)
midgut = DJ junction to splenic flexure (SMA)
hindgut = splenic flexure to anus (IMA)

Question 2

2 ducts and papilla of pancreas

Answer 2

• Wirsung (main. bigger duct): major duodenal papilla

- Santorini (accessory): minor duodenal papilla

Question 3

pancreas divisum def

Answer 3

congenital abnormality where each bud keps it duct: minor duct (smaller) is the main one and too narow for flow
(surgery to make papilla bigger)

Question 4

dx of pancreas divisum

Answer 4

ERCP (cannulation of major papilla, dye)

Question 5

annular pancreas def

Answer 5

bifid ventral bud wraps around duodenum

Question 6

liver development

Answer 6

liver, GB and bile ducts arise from a ventral outgrowth of the caudal foregut (week 4): hepatic diverticulum extends in septum transversum and divides in 2 parts

Question 7

2 parts of hepatic diverticulum in septum transversum and what they form

Answer 7

large cranial part = primordium of the liver

small caudal part = gallbladder

Question 8

what happens to common bile duct during ventral pancreas rotation

Answer 8

ventral rotates anteriorly but CBD rotates posteriorly and so now crosses behind the duodenum from right to left

Question 9

extrahepatic biliary atresia def

Answer 9

atresia (scarring down) of some bile ducts: jaundice and obstruction in first 3 months after birth

Question 10

extrahepatic biliary atresia cause and treatment

Answer 10

failure of bile ducts to recanalize. bypass of porta hepatis to bowel (so bile goes there directly)

Question 11

choledochal cyst def

Answer 11

prob in infants or neonates: cystic dilations of CBD: jaundice, cholangitis (bile infection), cysts

Question 12

choledochal cyst treatment + prognosis compared to extrahepatic biliary atresia

Answer 12

bypass surgery (put bowel right below liver so bile goes there directly). much better prognosis than extrahepatic biliary atresia

Question 13

congenital omphalomesenteric duct def

Answer 13

failure of yolk sac stalk to obliterate and disappear. many anomalies. most common is Meckel’s diverticulum

Question 14

possible problem in Meckel’s diverticulum

Answer 14

bowel obstruction bc twisting around

Question 15

other complications of Meckel’s diverticulum

Answer 15

• subumbilical mass (cyst forming around belly button)

- umbilical polyp (of intestinal mucosa. gets there bc of omphalomesenteric duct)

Question 16

cause of most jejunum and ileal problems congenital

Answer 16

vascular accidents (vessels in mesentery thrombose for some reason and disappear. ischemia of bowel. may happen in utero 20 wks)

Question 17

type 1 jejuno-ileal atresia

Answer 17

one dilated bowel part and one collapsed part. membrane interface between the two

Question 18

type IIIb jejuno-ileal atresia

Answer 18

curly bowel, appel core deformity, lot of bowel loss

Question 19

types 2, IIIA and 4 jejuno-ileal atresia

Answer 19

2 = defect in bowel
IIIA = mesentery gone + distance in separation
type 4 = many pieces

Question 20

surgery for jejuno-ileal atresia

Answer 20

remove obstruction and put bowel parts together

Question 21

what the hindgut forms

Answer 21

• colon from splenic flexure to anal canal

- epithelium of urinary bladder and most of urethra

Question 22

cloaca def

Answer 22

terminal part of hindgut. endoderm-lined chamber where hindgut and urinary system share space. receives allantois (diverticulum of the yolk sac)

Question 23

septum in cloaca

Answer 23

urorectal septum: separates the 2 systems in the cloaca. comes close to skin, near allantoic membrane

Question 24

urorectal septum in development (CLOACAL PARTITIONING steps)

Answer 24

comes down and fuses with cloacal membrane to form dorsal part (anal membrane) and ventral part (urogenital membrane)

Question 25

imperforate anus related to what

Answer 25

involves the perineal body (area of fusion of cloacal membrane and urorectal septum)

Question 26

Hirschsprung’s disease

Answer 26

failure of NCCs to migrate to a part of hindgut (failure of part of hindgut to receive ANS innervation)

Question 27

Hirschprung’s disease: what’s the problem + consequence

Answer 27

failure of PSS ganglion cells to dev in Auerbach’s and Meissner’s plexuses. a segment of bowel can’t relax. is constricted. segment proximal is dilated

Question 28

Hirschprung’s disease symptoms

Answer 28

bowel obstruction, severe constipation

Question 29

high imperforate anus charact in the male (more severe)

Answer 29

cloacal partitioning or anal canal formation defect. rectum fistula to urinary tract RECTOURETHRAL FISTULA. (rectum not at sphincter but anterior)

Question 30

low imperforate anus charact in male (less severe)

Answer 30

defect in anal membrane rupture. rectum fistula to perineum

PERINEAL FISTULA. (near the sphincter so surgery immediate)

Question 31

high imperforate anus charact in female (more severe)

Answer 31

rectum comes close to vagina (rarely enters it) RECTOCLOACAL or RECTOVAGINAL FISTULA

Question 32

high imperforate anus in female charact

Answer 32

rectum ends in common channel with urethra and vagina (persistent cloaca)

Question 33

low or intermediate imperforate anus in female charact

Answer 33

rectum ends in fistula with perineum (rectofourchette or rectovestibular fistula)