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Flashcards in embryology Deck (47):
1

intraembryonic body cavity

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

2

body folding

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

3

cantrells pentology

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

4

septum transversum

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

5

pluropericardial membrane

separate pleural and pericardial cavities

6

pleuroperitoneal membranes

separate pleural and peritoneal cavities

7

fromation of diaphragm

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

8

positional changes of diaphragm

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

9

diaphragm innervation

motor- phrenic n
sensory- central tendon phrenic, m- ICs

10

bochdack hernia

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

11

morgagni hernia

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

12

evagination of diaphrgam

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

13

germ layers

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

14

ends of tube

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

15

foregut

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

16

midgut

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

17

Hindgut

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

18

esophagus

partly obliterated during wk5, recanalizes by wk 8

19

atresias and stenoses

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

20

congenital hiatal hernia

esophagus fails to elongate, pulls stomach thru diaphragm

21

rotation of stomach

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

22

omental bursa

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

23

pyloric stenosis

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

24

spleen

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

25

liver and gallbladder

hepatic diverticulum -> outgrowth from 2nd part of duodenum

26

liver

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

27

gallbladder and cystic duct

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

28

pancreas

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

29

pancreatic duct system

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

30

annular pancreas

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

31

duodenum

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

32

duodenal stenosis

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

33

midgut development

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

34

yolk sac connection

vitteline duct
yolk
omphalenteric duct

35

midgut roation

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

36

retraction of herniated loops

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

37

omphalocele

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

38

gastroschisis

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

39

umbilical hernia

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

40

meckels (ileal) diverticulum

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).

41

failure of ascending colon to retroperitonealize

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

42

cloaca

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

43

urorectal septum

divides cloaca into urogenital sinus and anorectal canal

44

cloacal membrane

ruptures during wk 7

45

pectinate line

marks division btwm ectoderm and endoderm

46

hirschprungs disease

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

47

imperforate anus

failure of cloacal membrane to degenerate