134 Anatomy Applied to Medicine and Surgery. 



posed on removal of the cartilage and is then divided be- 

 tween two ligatures, the triangularis sterni muscle is 

 pushed to the right, the pericardium is exposed and the 

 sac is opened by an incision beginning close to the ster- 

 num and running obliquely downwards and outwards. In 

 this operation it is possible that the edge of the left pleura 

 may not present itself sufficiently to be in the way, al- 

 though, as will be seen under the subject of landmarks for 

 the pleura, there is considerable variation in the arrange- 

 ment of the pleural border in this situation. 



