MUSCLES OF THE ABDOMINAL CAVITY. 343 



fibres, from the cartilago-ensiformis, from the cartilages of the 

 seventh, and of all the inferior ribs on both sides. The fibres 

 from the cartilago-ensiformis, and from the seventh and eighth 

 ribs, run obliquely upwards and backwards; from the ninth and 

 tenth, transversely inwards and upwards, and from the eleventh 

 and twelfth, obliquely upwards. From these different origins 

 the fibres run, like radii from the circumference to the centre of 

 a circle ; and are 



Inserted into a cordiform tendon, of a considerable breadth. 

 which is situated in the middle of the diaphragm, and in which, 

 therefore, the fibres from opposite sides are interlaced. To- 

 wards the right side the tendon is perforated, by a triangular 

 hole, for the passage of the vena cava inferior ; and to the 

 upper convex part of it tlie pericardium and mediastinum are 

 connected. 



The inferior, lesser muscle, or 



Appendix of the Diaphragm, 



Arises from the second, third and fourth lumbar vertebra, by 

 eight heads, of which, two in the middle, commonly called its 

 crura are the longest, and begin tendinous. Between the crura, 

 the aorta and thoracic duct pass ; and on the outside of these, 

 the great sympathetic nerves and branches of the vena azygos 

 perforate the shorter heads. The muscular fibres run obliquely 

 upwards and forwards, and form in the middle two fleshy col- 

 umns, which decussate and leave an oval space between them 

 for the passage of the oesophagus and eighth pair of nerves. 

 Two bow shaped ligaments are formed on either side at the 

 lower border of this muscle, as seen in fig. 88. 



Inserted, by strong fleshy fibres, into the posterior part of the 

 middle tendon. 



Use. The diaphragm is the principal agent in respiration, 

 particularly in inspiration : for when it is in action, the fibres, 

 from their different attachments, endeavor to bring themselves 



formed in the interior of the thorax by the diaphragm : tlie position of this arcli 

 on the right side, is indicated by a dotted line. //, Columns, or crura of the 

 lesser muscles of the diaphragm, arising from the lumbar vertebrae, i, Leva- 

 tores costarum, longiores, and breviorcs. 



