Thoracic Cavity Development

Question 1

Intraembryonic Coelom

Answer 1

Primordium of the embryonic body cavities

Develops during the 4th week

Hoseshoe-shaped cavity

Develops in the lateral mesoderm

Question 2

Cranial End of Intraembryonic Coelom

Answer 2

• Future pericardial cavity
• Embryo undergoes the head-fold
  
  • this brings the pericardium and heart ventrocaudally to take its position anterior to the foregut

Question 3

Caudal Limbs of Intraembryonic Coelom

Answer 3

• Future pleural and peritoneal cavities
• Opens to the extraembryonic coelem
  
  • accomodates growth & movement of organs
  • Loses connection with extraE C @ week 10
• Embryo folds in the horizontal plane
  
  • brings 2 caudal limbs together ventrally
  • these then fuse to form peritoneal cavity
• Results in a gut tube suspended b/t 2 layers of membrane (Mesentary) suspended from body wall of embryo

Question 4

Mesentery

Answer 4

• double layer of peritoneum that extedns from the abdominal wall
• Conveys blood vessels, nerves, and lymphatics to organs
• Divides the peritoneal cavity into right & left halves

Question 5

Types of Mesentery

Answer 5

• Dorsal mesentary
  
  • Permanent structure
• Ventral Mesentary
  
  • remains attached to caudal part of the foregut
  • suspends primordial liver, stomach and proximal part of duodenum
  • becomes falciform ligament and lesser omentum

Question 6

Parietal Peritoneum

Answer 6

Covers body wall

Question 7

Visceral Peritoneumm

Answer 7

covers the organ

Question 8

Divisions of the Embryonic Body Cavity

Answer 8

• Pericardioperitoneal canals
• Pleuropericardial Membranes
• Pleuroparietal Membranes
• Diaphragm

Question 9

Pericardioperitoneal canals

Answer 9

• Term for intraembryonic coelom after embryonic folding
• Lies lateral to the forgut (future esophagus)
• Dorsal to the Septum Transversum (future central tendon of the diaphragm)
• Partitions form in each canal due to developing bronchial buds

Question 10

Cranial ridges of pericardioperitoneal canals

Answer 10

• Pleuropericardial folds
• located superior to developing lungs
• Separate pleural from pericardial cavities

Question 11

Caudal Ridges of pericardioperitoneal canals

Answer 11

• Pleruoperitoneal folds
• Located inferior to developing lungs
• Separate from peritoneal cavities

Question 12

Pleuropericardial Membranes

Answer 12

• Enlargement of the pleuropericardial folds becomes the partition that separates the pleural from the pericardial cavities
• Contain common cardial veins
• Drain the primordial venous system into the sinus venous of the primordial heart