thoracic cavity

Question 1

origin of the coelom

Answer 1

cavitation within mesoderm

Question 2

what is the function of the coelom

Answer 2

to facilitate motion of the organs, giving them space and flexibility to move

(lung expansion/contraction, heart beating, stomach filling)

Question 3

how is the intra-embryonic coelom partitioned into the pleural/pericardial and peritoneal cavities?

Answer 3

• formation of the diaphragm separates the cavities
• most of the diaphragm comes from the septum transversum
• joins with mesentary (peritoneum) of esophagus
• pleural and peritoneal membranes growing out to join

Question 4

how are the pleural and pericardial cavities formed?

Answer 4

• Pleuripericardial folds grow out and unite between heart and lungs, forming the fibrous layer of the pericardium
• this process encaptures the phrenic nerve, which can be found on front of the heart

Question 5

coverings of the heart

Answer 5

• pleuropericardial folds => fibrous layer of pericardium
• heart also becomes invested in mesothelium from the coelom, the serous layer of the pericardium.
• parietal layer of serous pericardium = insider of fibrous pericardium
• visceral layer of serous pericardium = epicardium of the heart

Question 6

coverings of the lungs

Answer 6

• coelomic lining on the body wall side = parietal pleura
• very pain sensitive because innervated from somatic nerves of body wal (intercostals and phrenic)
• coelomic lining on the lung side = visceral pleura
• less pain sensitive because autonomic innervation