Lec30: Embryology, Midgut and Hindgut Flashcards Preview

Structures (ASV) > Lec30: Embryology, Midgut and Hindgut > Flashcards

Flashcards in Lec30: Embryology, Midgut and Hindgut Deck (33):
1

midgut: adult derivatives

duodenum distal to common bile duct, jejunum, ileum, cecum, appendix, ascending colon, proximal TV colon

2

midgut and foregut relative to yolk sac during folding

midgut: in front of yolk sac
foregut: behind yolk sac

3

what suspends the midgut as it loops

dorsal mesogastrium

4

primary vasculature to midgut

SMA

5

when's / how's physiological midgut herniation

beginning of week 6 - herniates into umbilical stump
cranial and caudal portions of midgut loop, communicate w/ yolk sac
loop returns into abdomen week 10

6

temporary cnxn between yolk sac, midgut

yolk stalk / vitelline duct / omphaomesenteric duct
week 6

7

loop of midgut that grows faster

cranial

8

rotation of midgut

week 6, counterclockwise around SMA axis, mostly cranial loop, while within umbilicus; week 10, back in abdominal cavity, caudal loop rotates 180 degrees

9

caudal loop of midgut =

large intestine

10

what ends up in lower right quadrant, why

cecum, appendix
270 degree rotation of midgut

11

small intestine re: SMA after rotation

posterior to SMA

12

fixation of intestines in abdominal cavity

small intestine- ventral mesentery, mesogastrium
ascending colon- fused to posterior abdominal wall, then that disappears

13

line of attachment of small intestine that persists

line from duodenojejunal junction, ileocecal junction

14

how cecum forms

week 6, diverticulum of caudal limb of midgut loop

15

appendix formation

cecum enlarges, folds; forms vermaform appendix, enters cecum medially

16

meckel's diverticulum

omphalomesenteric gut connects yolk stalk-midgut loop, usually obliterated
if not, gut remains around umbilicus, abdominal wall-gut communicate

17

hindgut derivatives

left TV colon, descending colon, sigmoid colon, rectum, superior portion of anus, epithelial lining urinary bladder, urethra

18

midgut-hindgut anatomical difference

SMA branches leave off - IMA branches pick up vascularization

19

hindgut blood supply

IMA

20

cloaca def'n, lining, membrane

expanded distal hindgut
lining: endoderm
outside: ectoderm of protodeum (anal pit)

21

what empties into cloaca

allantois

22

clocal membrane formed by

urorectal septum growing toward distal part of embryo, joins w/ ectoderm

23

urorectal septum

infoldings of lateral cloacal walls partition cloaca into ventral urogenital sinus, dorsal rectum
divides CLOACAL SPHINCTER

24

cloaca partitioning

week 7
distal urorectal septum fuses w/ cloacal membrane > anal membrane, urogenital membrane, perineal body

25

cloacal sphincter regions

ventral: becomes pelvic floor muscles
dorsal: anal sphincter (continence!)

26

anal membrane

disappears, end of week 8
then rectum communicate w/ amniotic cavity

27

anal canal parts

upper 2/3: hindgut
lower 1/3: proctodeum
junction: pectinate line, anal membrane

28

pectinate line- cell change

columnar cells of hindgut > cuboidal, cutaneous cells of proctodeum > anus

29

anal sphincter formed

splanchnic mesoderm, caused by hox genes

30

arterial supply to anal canal

upper 2/3: superior rectal artery (of IMA)
lower 1/3: inferior rectal artery (of internal pudendal a. of iliac a.)

31

lymphatic drainage, anal canal

upper 2/3: inferior mesenteric lymph nodes
lower 1/3: superficial inguinal lymph nodes

32

innervation of anal canal

upper 2/3: ANS, T1-L1, S2-4, involuntary
lower 1/3: inferior rectal nerve, branch of pudendal nerve S2,3,4, voluntary control

33

imperforate anus

failure of apoptosis so solid endodermal tissue, no anal sphincter/opening to outside