110 CLINICAL APPLIED ANATOMY. 



muscles into the subcutaneous tissues, there to produce 

 " surgical emphysema." The air thus forced into the tissues 

 may travel through the whole of the subcutaneous tissues of the 

 body, except where the skin is tightly bound down, as for 

 instance in the regions of the palms of the hands, the soles of 

 the feet, the auricles, and to a certain extent the scalp. 



The ribs which are most commonly fractured are those of the 

 middle of the series, the fifth, sixth, seventh, eighth, and ninth. 

 Those in the upper part of the thorax are more protected, the 

 first being practically covered by the clavicle, and therefore 

 fracture of the first rib seldom occurs unless accompanied by a 

 fracture of the collar bone. The lower ribs, the eleventh and 

 twelfth, having no attachment through their costal cartilages 

 with the costal cartilages of the other ribs, easily slip out of the 

 way when violence is applied, and thus generally escape a 

 solution of their continuity. 



Fracture of any of the ribs below the sixth may involve injury 

 to the diaphragm and the subjacent liver on the right and of the 

 spleen and possibly the stomach on the left, whilst fracture of 

 the tenth, eleventh, and twelfth may be accompanied by damage 

 to the kidneys. 



In the union of a fractured rib much external callus is usually 

 in evidence, owing to the fact that it is well-nigh impossible to 

 get complete immobility of the fractured ends, on account of their 

 movement during respiration. 



FBACTURES OP THE STERNUM. 



Fracture of the sternum is a rare fracture, and usually pro- 

 duced by direct violence. It is in most cases associated with 

 such grave injury to the thoracic viscera, particularly the heart, 

 that the sufferer but rarely survives. The sternal fragments are 

 driven backwards, and come into violent contact with the right 

 side of the heart or the great vessels which lie immediately 

 behind the bone. The shock is so severe that, even if no vessel 

 is torn, death nearly always ensues. 



