INSPIRATION 



289 



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- 



CEsophagus 

 L*fl subcUvten artery 

 Left common carotid artery 



Left superior intercostal vein 

 Left innominate vei 



Parietal 

 pleura 

 (cut edge) 



ihagus 



Diaphrasm 



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

 lung is removed. (Cunningham.) 



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 



