Embryology

Question 1

Septum Transversum

Answer 1

plate of mesoderm which forms from cervical somites 345 and is pushed down by the heart

• forms most of the diaphragm (rest is pleuroperitoneal memb)
• not complete, leaves openings called pericardiacophrenic calanals

Question 2

Pleuroperitoneal membrane

Answer 2

separate pleural and peritoneal cavities and forms the remainder of the diaphragm

Question 3

Bochdalek hernia (posterior/lateral defect)

Answer 3

Congenital diaphragmatic hernias
incomplete formation of the pleuroperitoneal membranes on left—>SI herniates thru—>compress heart and lungs—>pulm hypoplasia

Question 4

Morgagni hernia (parasternal hernia)

Answer 4

anterior defect in muscular portion of diaphragm

generally small, no hypoplasia, not detected till later

Question 5

eventration of diaphragm

Answer 5

unilateral weakness of diaphragm due to failure of myotome migration
viscera balloons into the thorax (still covered by diaphragm)

Question 6

the 3 germ layers contributing to gut tube formation

Answer 6

endoderm—>epi and glands
mesoderm—>CT and smooth muscle
Ectoderm—> epi at ends of tube

Question 7

Foregut

Answer 7

pharynx, eso, stomach, 1 and 2 of Duo, liver, GB, pancreas, spleen
celiac trunk

Question 8

Midgut

Answer 8

3 and 4 of duo, SI, cecum, appendix, ascending colon, proximal 2/3 of transverse colon

SMA

Question 9

Hindgut

Answer 9

distal 1/3 of transverse colon to upper anal canal

IMA

Question 10

Stenosis

Answer 10

occurs when recanalization is incomplete
namely occurs in esophagus
and duodenum (esp 3rd and 4th parts)—>green vomit

Question 11

atresia

Answer 11

occurs when recanalization is absent

namely occurs in esophagus

Question 12

pyloric stenosis

Answer 12

caused by hypertrophy of smooth muscle around pyloric sphincter
presents with forcible vomiting after eating`

Question 13

dorsal pancreatic bud

Answer 13

from endodermal outgrowths from the duodenum
gives to most of the body of the pancrease
gives rise to the accessory pancreatic duct

Question 14

ventral pancreatic bud

Answer 14

gives rise to head and uncinate process

gives rise to main pancreatic duct

Question 15

annular pancreas

Answer 15

bifid ventral pancreatic bud

encircle the duodenum—>constriction—>atresia

Question 16

Omphalocele

Answer 16

failure of midgut to return into abdomen

tissue protrudes thru and is covered by amniotic membrane

Question 17

Gastroschisis

Answer 17

gut herniates thru weakness in body wall, lateral to umbilicus (R)
from incomplete fusion of ventral body wall

NOT COVERED BY AMNIOTIC MEMBRANE

Question 18

Umbilical hernia

Answer 18

gut herniates into umibilical cord after returning to abdomen (due to imperfectly closed umbilicus

herniated tissue covered by skin etc

Question 19

Meckels (Ileal) diverticulitis

Answer 19

results from persistence of vitelline duct 
2% of population 
2x more in men 
distal 2 ft of ileum 
2 in long
2% symptomatic 
usually before age 2 
2 types of tissue (gastric, pancreatic)

Question 20

Hirschprungs disease

Answer 20

congenital megacolon
failure of neural crest cells to migrate into caudal LI or rectum—> no PSNS ganglia —> no perastalsis–>accum of feces

Question 21

Rectourethral and rectovaginal fistulas

Answer 21

occur to improper formation of urorectal septum —> anterior displacement of hindgut

Question 22

imperforate anus

Answer 22

failure of cloacal membrane to degenerate

Question 23

Cantrell’s Pentology

Answer 23

1) cleft sternum
2) ectopic cordis
3) gastroschisis or omphalocele
4) diaphragmatic hernia (anterior)
5) Congenital heart defect