Lecture 17: Formation of Body Cavities Flashcards
when does formation of intraembryonic ceolom start
early in 4th week
what happens with lateral body folding
amnion engulfs entire embryo, yolk sac pinched off to form the gut
what are the embryonic body cavities initially
pericardial and peritoneal, connected by 2 pericardio-peritoneal canals
parietal layer vs visceral layer mesoderm
parietal = somatic visceral = splanchnic
mesentery
a double layer of peritoneum that connects an organ to the body wall
what travels in the mesentery
blood vessels and nerves
dorsal mesentery
suspends caudal foregut, midgut, and hindgut in the peritoneal cavity
ventral mesentery
dissapears except in the proximal foregut (stomach and proximal duodenum)
arterial supply to primitive gut
celiac (foregut), superior mesenteric (midgut), inferior mesenteric (hindgut)
communication between intra and extraembryonic coelom
provides space for physiologic herniation of the midgut (intestinal folds happen in extra), closes at week 10 when intestines have returned to the abdomen
division of embryonic body cavity
pleuropericardial folds
what do pleuropericardial membrans contain
cardinal veins and phrenic nerves
what separates pericardial and pleural cavities
pleuropericardial membrans - fuse with mesenchyme ventral to esophagus to separate the cavities
4 EMBRYONIC components of diaphragm
septum transversum, pleuroperitoneal membranes, dorsal mesentary of esophagus, muscular in growth from lateral body walls
septum transversum
mesoderm of central tendon of diaphragm, begins cranial to heart, migrates via craniocaudal folding to separate heart from liver
where does the pleuroperitoneal membrane grow in from
lateral body walls
what does the pleuroperitoneal membrane fuse with
dorsal mesentery of esophagus and septum transversum
what closes pleuroperitoneal openings
myoblasts that migrate into the membrane
pleuroperitoneal membranes effect on fetal vs adult
large in fetal, small in adult
dorsal mesentery of esophagus
forms median portion of diaphragm
crura
pair of muscle bundles that form from myoblasts that have migrated into dorsal mesentary
muscular ingrowth of lateral body wall
expanding pleural cavities divide body wall into external and internal layer
external vs internal layer
external : definitive body wall
internal: peripheral diaphragm
what does muscular ingrowth of lateral body wall create
costodiaphragmatic recesses/angles
innervation of diaphragm
C3-4-5
phrenic nerve
2, motor and sensory innervations
CDH
congenital diaphragmatic hernia
closure timing of diaphragm
right closes before left
what happens in a CDH
abdominal viscera herniate from abdomen into chest
explain the formation of the diaphragm
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
