1092 



THE EESPIEATORY SYSTEM. 



The foetal lung differs in a marked degree from the lung of an individual who 

 has breathed. After respiration is fully established, the lung soon comes to occupy 

 almost the whole space aUotted to it in the pleural cavity ; in the foetus, on the 

 other hand, the lung is packed away at the dorsal aspect, and occupies a relatively 

 much smaller amount of space in the thoracic cavity. Further, it is firm to the touch, 

 and sinks in water. It is only when air and an increased supply of blood are 



Recurrent nerve 

 Inferior thyreoid vein 



Right vagus nerve 



Bifurcation of inno- 

 minate artery 



Right subclavian 

 vessels 



Internal mammary 

 artery 



Right inno- 

 minate vein 



RIGHT LOBE OF 

 THYMUS 



Sterno-hyoid muscle 

 Sterno-thyreoid muscle 

 Sterno-mastoid muscle 

 Thyreoid gland 

 Internal jugular vein 

 Phrenic nerve 



Scalenus anterior 



- Subclavian artery (left) 

 Left vagus nerve 



Superior lobe 

 of right lung 



Middle lobe 

 of right lung ~~| 



Basal lobe of 

 right lung 



ubclavian vein (left) 

 Common carotid artery 

 Left innominate vein 



First rib 

 Aortic arch 



LEFT LOBE OF 

 THYMUS 



Left lung 



Heart 



Pulmonary fissure 



Pericardium 



FIG. 868. DISSECTION OF THORAX AND ROOT OF THE NECK FROM THE FRONT TO SHOW THE RELATIONS 

 OF THE LUNGS, PERICARDIUM, AND THYMUS. 



introduced into the lung that it assumes the soft spongy and buoyant qualities 

 which are characteristic of the adult lung. 



Form of the Lungs. The lungs are accurately adapted to the walls of the 

 pleural chambers in which they are placed, and in the natural state they bear OE 

 the surface impressions and elevations which are an exact counterpart of thf 

 irregularities on the walls of the cavity in which they lie. 



When care has been taken to harden it in situ, each lung presents foi 

 examination an apex, diaphragmatic, mediastinal, and costal surfaces, and ventra 

 (anterior) and inferior borders. 



The apex pulmonis is blunt and rounded, and rises above the level of th< 

 oblique first costal arch to the full height of the cupula pleurae. It therefor* 

 protrudes, above, through the superior aperture of the thorax, into the root of th- 



