INSPIRATION 



277 



bucket. The elevation of the ribs is accompanied by a slight opening out of 

 the angle which the bony part forms with its cartilage, and thus an additional 

 means is provided for increasing the antero-posterior diameter of the chest. 

 The movements of all the ribs except the twelfth consist of a rotation up- 



Esophagus 



Left subclavian artery 

 Left common carotid artery 

 Left superior intercostal vein 

 Left innominate vein 



Parietal pleura 

 (cut edge) 



Pericardium 



Parietal pleura 

 (cut edge) 



Aortic arch 



Pulmonary artery 

 Bronchus 



Pulmonary veins 

 Esophagus 



Diaphragm 



FIG. 229. Thorax from the Left, Showing Left Pleural Sac, and the Diaphragm. The 



lung is removed. 



ward, forward, and outward. The twelfth presents only rotation down- 

 ward and backward. 



The muscles involved in these movements of the ribs are the external 

 intercostals and the part of the internal intercostals situated between the 

 costal cartilages. Their action is to widen the intercostal spaces. The 

 scaleni fix the first and second ribs, thereby making a fixed point of action 



