Pleural Cavities & Mediastinum

Question 1

pleural cavities

Answer 1

• potential space between the layers of pleura

- contains capillary layer of serous pleural fluid

Question 2

pericardial cavity

Answer 2

• potential space between opposing layers of parietal and visceral layers of serous pericardium
• normally contains thin film of fluid that enables the heart to move and beat in a frictionless environment

Question 3

thoracic inlet

Answer 3

• superior thoracic aperture

Question 4

thoracic outlet

Answer 4

• inferior thoracic aperture

Question 5

parietal pericardium

Answer 5

• internal surface of fibrous pericardium lined with glistening serous membrane

Question 6

visceral pericardium

Answer 6

• reflection of parietal pericardium onto heart at great vessels (aorta, pulmonary trunk and veins, and superior/inferior vena cavae)

Question 7

mediastinum

Answer 7

• central compartment of thoracic cavity
• occupied by mass of tissue between the two pulmonary cavities
• contains all thoracic viscera and structures except lungs

Question 8

pleural recesses

Answer 8

• where two layers of parietal pleura touch each other
• costodiaphragmatic recess = where parietal costal and parietal diaphragmatic pleura meet
• costomediastinal recess = where parietal costal and parietal mediastinal pleura meet

Question 9

pleural sac

Answer 9

• consists of two membranes: parietal and visceral

Question 10

What are the boundaries of the inferior mediastinum? What structures fall in this portion?

Answer 10

• between transverse thoracic plane and diaphragm

- further divided into anterior, middle, and posterior parts

Question 11

What are the boundaries of the anterior mediastinum? What structures fall in this portion?

Answer 11

• anterior border is sternum, lateral borders are mediastinal pleura, posterior border is pericardium

Question 12

What are the boundaries of the middle mediastinum? What structures fall in this portion?

Answer 12

• anterior border is anterior margin of pericardium, posterior border is posterior border of fibrous pericardium, lateral borders are mediastinal pleura
• pericardium and its contents (heart and roots of its great vessels)

Question 13

What are the boundaries of the posterior mediastinum? What structures fall in this portion?

Answer 13

• posterior border is bodies of thoracic vertebrae, anterior border is posterior border of fibrous pericardium, lateral borders are mediastinal pleura

Question 14

pleural tap (thoracocentesis)

Answer 14

• insertion of hypodermic needle through an intercostal space (9th space in midaxillary line during expiration) into pleural cavity to obtain sample of fluid or remove blood/pus
• needle inserted superior to rib, high enough to avoid collateral branches of nerves/blood vessels
• needle passes through intercostal muscles and costal parietal pleura into pleural cavity

Question 15

Innervation of the pleura?

Answer 15

• Vagus nerve (CN X) ends up in lungs and heart
• visceral pleura have afferents traveling back with parasympathetic
• parietal pleura have afferents that feed back into somatic system
• phrenic nerve supplies diaphragm –> runs through mediastinum

Question 16

air/fluid/blood/tumor in pleural cavity

Answer 16

• accumulation of air in pleural cavity –> pneumothorax
• accumulation of fluid in pleural cavity –> hydrothorax
• accumulation of blood in pleural cavity –> hemothorax

Question 17

pericardial tap (pericardiocentesis)

Answer 17

• drainage of fluid from pericardial cavity to relieve cardiac tamponade (compression of heart caused by fluid collecting in pericardium)

Question 18

How would a cervical injury with a knife affect the pleura?

Answer 18

• would cause a hemothorax?