Quiz 2 - Thoracic Embryology Flashcards Preview

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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)


septum transversum

-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


pleuropericardial membranes

-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?

-smooth muscle
-blood vessels
-connective tissues
-cartilages of trachea, bronchi, lungs
-visceral pleura


parietal layer of lateral plate mesoderm becomes what?

-parietal pleura
-fibrous pericardium
-septum transversum


tracheoesophageal ridge

-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


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


paraxial mesoderm has what role in thoracic development?

--> somites --> myotome --> forms skeletal muscle of anterolateral trunk and diaphragm