Embryology of the Abdomen

Question 1

the splanchnic mesoderm forms _

Answer 1

mesentery, muscle, connective tissue, and blood vessels of digestive tube

Question 2

What does the endoderm form in the digestive tract?

Answer 2

epithelial linings, bile ducts and gallbladder, parenchyma of liver (hepatocytes), and parenchyma of pancreas (enzymes and endocrine cells)

Question 3

foregut organs

Answer 3

esophagus, stomach, liver, gallbladder, pancreas, upper duodenum

Question 4

foregut arterial supply

Answer 4

celiac trunk

Question 5

foregut nerve supply

Answer 5

vagus (parasympathetic) and thoracic splanchnics (sympathetic)

Question 6

midgut organs

Answer 6

lower duodenum, jejunum, ileum, cecum, appendix, ascending colon, proximal 2/3 of transverse colon

Question 7

midgut arterial supply

Answer 7

superior mesenteric arteries

Question 8

midgut nerve supply

Answer 8

vagus (parasympathetic) and thoracic splanchnics

Question 9

hindgut organs

Answer 9

distal 1/3 of transverse colon, descending colon, sigmoid colon, rectum, upper anal canal

Question 10

hindgut arterial supply

Answer 10

inferior mesenteric arteries

Question 11

hindgut nerve supply

Answer 11

pelvic splanchnics (parasympathetic) and lumbar/sacral splanchnics (sympathetic)

Question 12

pyloric sphincter allows _

Answer 12

movement from stomach to duodenum

Question 13

pyloric stenosis

Answer 13

hypertrophy of pyloric sphincter (always contracted) so shuts off flow from stomach to duodenum

Question 14

pyloric stenosis symptoms

Answer 14

olive-shaped mass, visible peristalsis, and nonbilious projectile vomiting

Question 15

pyloric stenosis is associated with _

Answer 15

exposure to antibiotics during pregnancy

Question 16

bile duct atresion

Answer 16

leads to lack of bile entering the duodenum and dilation of gallbladder and ducts above blockage; bowl movements are clay colored

Question 17

ventral pancreatic bud develops as an extension of _

Answer 17

common bile duct

Question 18

dorsal pancreatic duct forms as an extension of _

Answer 18

stomach

Question 19

annular pancreas

Answer 19

migration of ventral pancreatic duct is disrupted causing a ring of tissue around the duodenum that blocks movement of digestive products

Question 20

subhepatic appendix

Answer 20

appendix ends up underneath the liver because ascending colon does not migrate left

Question 21

umbilical herniation

Answer 21

abdominal cavity is too small for organs at first but as it expands the guts will go back in

Question 22

omphalocoele

Answer 22

guts did not go back in and are covered with amnion/peritoneum

Question 23

gastroschisis

Answer 23

guts did not go back in but are exposed (no amnion covering)

Question 24

vitelline fistula

Answer 24

vitelline ducts fail to close causing meconium discharge from umbillicus

Question 25

meckel diverticulum

Answer 25

partial closure of vitelline duct but remaining attachment to ileum; can have gastric or pancreatic tissue secreting HCl so will have ulcerations

Question 26

intussuception

Answer 26

one segment of intestine is inside of another causing obstruction

Question 27

volvulus

Answer 27

abnormal twisting of GI tract

Question 28

duodenal atresia

Answer 28

failure to recanalize; associated with Down Sydndrome

Question 29

jejunal and ileal atresia

Answer 29

often a result of volvulus; leads to necrosis of fetal intestine

Question 30

urorectal septum

Answer 30

if it does not form it can result in urorectal fistula, rectovaginal fistula, or rectoperineal fistula; all result in anal agenesis

Question 31

congenital megacolon (Hirschsprung)

Answer 31

neural crest cells fail to migrate into a portion of hindgut resulting in distended colon