Lecture 17: Formation of Body Cavities

Question 1

when does formation of intraembryonic ceolom start

Answer 1

early in 4th week

Question 2

what happens with lateral body folding

Answer 2

amnion engulfs entire embryo, yolk sac pinched off to form the gut

Question 3

what are the embryonic body cavities initially

Answer 3

pericardial and peritoneal, connected by 2 pericardio-peritoneal canals

Question 4

parietal layer vs visceral layer mesoderm

Answer 4

parietal = somatic
visceral = splanchnic

Question 5

mesentery

Answer 5

a double layer of peritoneum that connects an organ to the body wall

Question 6

what travels in the mesentery

Answer 6

blood vessels and nerves

Question 7

dorsal mesentery

Answer 7

suspends caudal foregut, midgut, and hindgut in the peritoneal cavity

Question 8

ventral mesentery

Answer 8

dissapears except in the proximal foregut (stomach and proximal duodenum)

Question 9

arterial supply to primitive gut

Answer 9

celiac (foregut), superior mesenteric (midgut), inferior mesenteric (hindgut)

Question 10

communication between intra and extraembryonic coelom

Answer 10

provides space for physiologic herniation of the midgut (intestinal folds happen in extra), closes at week 10 when intestines have returned to the abdomen

Question 11

division of embryonic body cavity

Answer 11

pleuropericardial folds

Question 12

what do pleuropericardial membrans contain

Answer 12

cardinal veins and phrenic nerves

Question 13

what separates pericardial and pleural cavities

Answer 13

pleuropericardial membrans - fuse with mesenchyme ventral to esophagus to separate the cavities

Question 14

4 EMBRYONIC components of diaphragm

Answer 14

septum transversum, pleuroperitoneal membranes, dorsal mesentary of esophagus, muscular in growth from lateral body walls

Question 15

septum transversum

Answer 15

mesoderm of central tendon of diaphragm, begins cranial to heart, migrates via craniocaudal folding to separate heart from liver

Question 16

where does the pleuroperitoneal membrane grow in from

Answer 16

lateral body walls

Question 17

what does the pleuroperitoneal membrane fuse with

Answer 17

dorsal mesentery of esophagus and septum transversum

Question 18

what closes pleuroperitoneal openings

Answer 18

myoblasts that migrate into the membrane

Question 19

pleuroperitoneal membranes effect on fetal vs adult

Answer 19

large in fetal, small in adult

Question 20

dorsal mesentery of esophagus

Answer 20

forms median portion of diaphragm

Question 21

crura

Answer 21

pair of muscle bundles that form from myoblasts that have migrated into dorsal mesentary

Question 22

muscular ingrowth of lateral body wall

Answer 22

expanding pleural cavities divide body wall into external and internal layer

Question 23

external vs internal layer

Answer 23

external : definitive body wall

internal: peripheral diaphragm

Question 24

what does muscular ingrowth of lateral body wall create

Answer 24

costodiaphragmatic recesses/angles

Question 25

innervation of diaphragm

Answer 25

C3-4-5

Question 26

phrenic nerve

Answer 26

2, motor and sensory innervations

Question 27

CDH

Answer 27

congenital diaphragmatic hernia

Question 28

closure timing of diaphragm

Answer 28

right closes before left

Question 29

what happens in a CDH

Answer 29

abdominal viscera herniate from abdomen into chest

Question 30

explain the formation of the diaphragm

Answer 30

1) septum transversum (mesoderm) between heart tube and liver is precursor to central tendon of diaphragm
2) paired pleuroperitoneal membranes (somatic mesoderm) develop from dorsal and dorsolateral body wall
3) dorsal mesentery of esophagus invaded by myoblasts and forms crura
4) body wall contributes muscle to peripheral portions of definitive diaphragm