VISCERA 21 



THORACIC VISCERA. 



Remove the skin from the anterior part of the 

 thorax, and cut aivay the ribs and sternum. 



1. The Pleurae are the membranes which line the 

 two sides of the thorax and are reflected over the 

 lungs and great blood - vessels. They meet in 

 the mid-line and form a double-\valled septum, 

 the mediastinum. The ventral part contains be- 

 tween its walls the heart and its pericardium. 

 The dorsal portion contains the oesophagus, tra- 

 chea, and blood-vessels. 



2. The Lungs are the pinkish lobulated bodies 

 lying on either side in the thoracic cavity. The 

 lungs normally fill the entire thoracic cavity ex- 

 cept that part occupied by the heart. When the 

 thorax is opened they are usually found collapsed. 

 The right lung is divided into four lobes and the 

 left into two. 



The lungs may be artificially inflated to better 

 demonstrate the lobes. 



3. The Trachea may be seen, by pushing aside 

 the heart and lungs, as a cartilaginous, annulated 

 tube. This leads from the pharynx to the base of 

 the lungs, where it divides into two bronchi, one 

 of which goes to each lung and there subdivides 

 into numerous smaller bronchi which penetrate 

 the various lobes. 



4. The Thymus Gland is the mass of glandular 



