embryology

Question 1

intraembryonic body cavity

Answer 1

forms w/in lateral plate mesoderm
divides lateral plate mesoderm into parietal (somatic) and visceral (splanchnic) mesoderm
patietal -> parietal serousmembranes
visceral-> visceral serous membranes and mm/CT of organs

Question 2

body folding

Answer 2

fusion of bady wall ventrally
incorportates intraembryonic cavity fully into embryo
retains connection to extraembryonic cavity in midgut until wk 12

Question 3

cantrells pentology

Answer 3

cleft sternum
ectopic cordis
gastroschisis or omphalocele
diaphragmatic hernia
congenital heart defects

Question 4

septum transversum

Answer 4

plate of mesoderm which separates thoracic and peritoneal cavities
will from bulk of diaphragm
does not completely separate throacic and abdominal cavities; leaves openings on either side of foregut called pericardioperitoneal canals

Question 5

pluropericardial membrane

Answer 5

separate pleural and pericardial cavities

Question 6

pleuroperitoneal membranes

Answer 6

separate pleural and peritoneal cavities

Question 7

fromation of diaphragm

Answer 7

from septum transversum (central tendon and m) 
pleuroperitoneal membranes (central tendon)

Question 8

positional changes of diaphragm

Answer 8

mesoderm of diaphragm forms from cervical somites 3-5
differential growth of body leads to decent
by wk 8 diaphragm is at LV1

Question 9

diaphragm innervation

Answer 9

motor- phrenic n

sensory- central tendon phrenic, m- ICs

Question 10

bochdack hernia

Answer 10

posterolateral defect
incomplete formation of pleuroperitoneal membranes, usually on left
small intestine and/or other viscera herniate thru defect into pleural cavity
lungs and heart compressed -> pukmonary hypoplasia

Question 11

morgagni hernia

Answer 11

parasternal hernia
anterior defect in mm of diaphragm
small, sometimes not dectected until child several yrs old

Question 12

evagination of diaphrgam

Answer 12

weakness (usually unilateral) of diaphragm due to failure of myotome migration
allows abdominal viscera to balloon into thoracic cavity

Question 13

germ layers

Answer 13

endoderm: epi and glands
mesoderm: CT and smooth m
ectoderm: epi at ends of tube (mouth- stomodeum, lower 1/3 of anal canal- proctodeum)

Question 14

ends of tube

Answer 14

rostral and caudel ends are originally closed by oropharyngeal and cloacal membranes, rupture during 4th and 7th wk

Question 15

foregut

Answer 15

pharynx (includes pharyngeal arches0
esophagus
stomach
parts 1 and 2 duodenum
liver
gallbaldder
pancreas 
spleen
supplied by celiac a

Question 16

midgut

Answer 16

parts 3 and 4 of duodenum, 
small intestines
ascending colon
cecum
appendix
proximal 2/3s of transverse colon
supplied by SMA
until wk 10 attached to yolk sac

Question 17

Hindgut

Answer 17

distal 1/3 of tranverse colon 
descending colon
sigmoid colon
rectum
proximal anal canal
supplied by IMA

Question 18

esophagus

Answer 18

partly obliterated during wk5, recanalizes by wk 8

Question 19

atresias and stenoses

Answer 19

malformation of tracheoesophageal septum or imcomplete recanalization of distal esophagus
recanalization incomplete = stenosis
recanalization completely absent = atresia

Question 20

congenital hiatal hernia

Answer 20

esophagus fails to elongate, pulls stomach thru diaphragm

Question 21

rotation of stomach

Answer 21

rotates 90 degrees clockwise around longitudinal axis
dorsal part (greater curavture) is now left, ventral part (lesser curvarture) is now right
also rotates around anteroposterior axis- pyloric part moves up and right, the cardiac portion down and left

Question 22

omental bursa

Answer 22

as stomach rotates it stretches the dorsal mesentery and comes to lie inferior and posterior to stomach

Question 23

pyloric stenosis

Answer 23

hypertrophy of smooth m around pyloric sphincter, present w/ forcible vomiting after eating

Question 24

spleen

Answer 24

froms from mesenchymal cells w/in 2 layers of dorsal mesogastrium
rotation of gut results in spleen being situates on left side of abdominal cavity

Question 25

liver and gallbladder

Answer 25

hepatic diverticulum -> outgrowth from 2nd part of duodenum

Question 26

liver

Answer 26

endoderm gives rise to parenchyma, mesoderm to stroma functions as hematopietic organ during 2nd month bile formation during wk 12

Question 27

gallbladder and cystic duct

Answer 27

forms from evagination of bile duct | b/c of rotation of foregut bile duct passes posterior to duodenum

Question 28

pancreas

Answer 28

arises from 2 (dorsal and ventral) endodermal outgrowths from duodenum rotation of duodenum causes fusion of buds most comes from dorsal, ventral forms lower portion of head and uncinate

Question 29

pancreatic duct system

Answer 29

main pancreatic duct derived from ventral pancreatic duct + distal dorsal pancreatic duct accessory pancreatic duct from proximal part of dorsal pancreatic duct

Question 30

annular pancreas

Answer 30

bifid ventral pancreatic bud, during rotation the bifid bud encircles the duodenum after fusion the annular tissue can constrict the duodenum surgical correction

Question 31

duodenum

Answer 31

arises from caudel end of foregut and rostral end o midegut as stomach rotates pulls duodenum superiorly and to right -> c shaped during month 2 the lumen is oblitereated, but recanalized

Question 32

duodenal stenosis

Answer 32

if vomit is white atresia is proximal to 2nd portion of duodenum if vomit is green atresia is distal to 2nd portion of duodenum

Question 33

midgut development

Answer 33

remains in communcation via vitelline duct until wk 10 physiologically herniates during gut wk 6 as space in abdominal cavity is reduced, pusehd into extraembryonic cavity midgut rotation retraction

Question 34

yolk sac connection

Answer 34

vitteline duct yolk omphalenteric duct

Question 35

midgut roation

Answer 35

primary intestinal loop undergoes a roation of 270 degrees counter clockwise mesentery proper becomes twisted and ascending/descending colon becomes secondarily retroperitoneal

Question 36

retraction of herniated loops

Answer 36

herniates intestinal loops return to abdominal cavity jejunum returns first and lies on left cecum returns last and lies in URQ and decends to LRQ, then appendix forms

Question 37

omphalocele

Answer 37

results from failure of midgut to return to abdominal cavity, tissue protrudes through umbilicus and is covered by amniotic membrance

Question 38

gastroschisis

Answer 38

results when gut herniates through weakness in body wall, typically occurs lateral to umbilicus (right) usually results from incomplete fusion of ventral body wall during folding herniated bowl is NOT covered by amniotic membrane

Question 39

umbilical hernia

Answer 39

results when gut herniates into umbilical cord after returning to abdominal cavity loops of bowl herniate through an imprefectly closed umbilicus herniated tissue covered by skin usually fixes on its own

Question 40

meckels (ileal) diverticulum

Answer 40

results from a persistence of the vitelline duct. Rule of 2’s: Occurs in 2% of population; 2x more likely in males; found within distal 2 feet of ileum; usually about 2 inches long; 2% become symptomatic usually before the age of 2; 2 types of tissue (gastric, pancreatic).

Question 41

failure of ascending colon to retroperitonealize

Answer 41

results in long mesocolon may allow for abnormal movement and potentially volvulus of colon retrocolic hernia can occur

Question 42

cloaca

Answer 42

distal most portion of gut tube | endoderm lined cavity which will contribute to formation of hindgut and urogenital system

Question 43

urorectal septum

Answer 43

divides cloaca into urogenital sinus and anorectal canal

Question 44

cloacal membrane

Answer 44

ruptures during wk 7

Question 45

pectinate line

Answer 45

marks division btwm ectoderm and endoderm

Question 46

hirschprungs disease

Answer 46

congenital megacolon failure of neural crest cells to mirgrate into caudal large intestine or rectum absence of parasympathetic ganglia

Question 47

imperforate anus

Answer 47

failure of cloacal membrane to degenerate