Flashcards in Quiz 2 - Thoracic Embryology Deck (31):
Intraembryonic coelem (body cavity) needs to be divided into ___ cavities
4 (3 in the thorax - the pericardial cavity and two pleural cavities for the lungs; 1 abdominal peritoneal cavity)
-a thickened sheet of somatic mesoderm that initially lies at the CRANIAL margin of the trilaminar germ disc
-eventually becomes the central tendon of the diaphram
during longitudinal folding, where does the septum transversum move?
-moves between the developing heart/primitive body cavity and the yolk sac
when longitudinal folding is complete, what has the septum transversum accomplished?
-it has divided the intraembryonic coelem into a more cranial pericardial cavity, and a more caudal peritoneal cavity
what allows communication between the pericardial and peritoneal cavities?
-the pericardioperitoneal canals on either side of the foregut
what do the pericardioperitoneal canals become?
-the pleural cavities, when the lungs grow into them
-extensions of the parietal layer of the lateral plate mesoderm
-grow into the cavity from the ventral and lateral body wall (along coronal plane)
-contain the common cardinal veins and the PHRENIC nerves
what separates the pleural cavities from the pericardial cavity?
-the pleuropericardial membranes fuse with each other and with the root of the lung
eventually, the pleuropericardial membranes become what?
-the fibrous pericardium
what 5 embryonic structures form the diaphragm and how?
1. septum transversum: gives rise to central tendon of diaphragm
2. pleuroperitoneal membranes: fuse with the septum transversum and dorsal mesentary of esophagus, separating the thoracic and abdominal cavities
3. dorsal mesentary of esophagus: gives rise to the crura of diaphragm
4. body wall: muscular ingrowth from body wall forms periphery of diaphragm
5. cervical somites (C3-C5): give rise to most of the diaphragmatic musculature
after longitudinal folding, where does the septum transversum temporarily lie?
-the cervical region, where HYPAXIAL myoblasts from the C3-C5 somites migrate into it
main innervation of the diaphragm
-the phrenic nerve (C3-C5; runs ANTERIOR to root of lung)
costal rim innervation and why is it not the phrenic nerve
-lower intercostal nerves
-this is because the lateral edges of the diaphragm develop from the body wall
congenital diaphragmatic hernia (CDH)
-failure of the pericardioperitoneal canals to close
-inferiorly allows abdominal viscera to herniate into the chest
eventration of diaphragm
-failure of the muscular body wall to extend to the pleuroperitoneal membrane on the affected side
-fibroelastic tissue replaces the missing muscular tissue, but this isn't strong enough to prevent the underlying viscera from pushing the hemidiaphragm into the thoracic cavity
respiratory diverticulum (4th week of development)
-the respiratory diverticulum pouches out from the ventral wall of the foregut (endoderm; esophagus).
-this will eventually form the epithelial lining of the respiratory airway passages
as it grows, to where does the diverticulum expand?
-it expands into the visceral layer of the lateral plate mesoderm that surrounds the gut tube
what will the visceral layer of the lateral plate mesoderm surrounding the gut tube form?
-cartilages of trachea, bronchi, lungs
parietal layer of lateral plate mesoderm becomes what?
-separates the respiratory diverticulum from the foregut/esophagus
tracheoesophageal fistula (TEF)
-abnormal connection of the esophagus and trachea
-results from the incomplete formation of the tracheoesophageal ridge
-1 in 3500 births
-many cases of TEF also involve esophageal atresia
-failure of the esophagus to develop as a continuous passage (ends in a blind pouch)
vesicles in lateral plate mesoderm --> ?
intraembryonic coelem (body cavity)
intraembryonic coelem --> ?
pericardial cavity, pericardioperitoneal canals
pleuropericardial membranes --> ?
fibrous pericardium --> separate pericardial and pleural cavities
septum transversum + pleuroperitoneal membranes --> ?
separate thoracic and abdominal caities
septum transversum --> ?
central tendon of diaphragm
foregut --> ?
respiratory diverticulum --> lung buds --> parenchyma of lungs
*foregut also becomes epithelium of larynx, trachea, bronchi, lungs
visceral layer of lateral plate mesoderm --> ?
stroma of lugs + visceral layer of pleura; also smooth muscle, blood vessels, CT of trachea, bronchi, lungs
parietal layer of lateral plate mesoderm --> ?
parietal layer of pleura; fibrous pericardium; septum transversum