MUSCLES OF THE THORAX. 383 



on its inner side, its fibres passing obliquely backwards and 

 downwards. They draw the ribs together. 



The Triangular is Sterni. 



Is on the posterior or cardiac face of the cartilages of the ribs, 

 and arises from the whole length of the cartilago ensiformis at 

 its edge, and from the inferior half of the edge of the second 

 bone of the sternum. The fibres go obliquely upwards and 

 outwards, to be inserted into the cartilages of the third, fourth, 

 fifth, and sixth ribs by fleshy and tendmous digitations. Its 

 use is to depress the ribs, and, consequently, to diminish the 

 cavity of the thorax. 



This muscle is frequently defective or redundant in the num- 

 ber of its heads, and is commonly more or less continuous with 

 the transversalis abdominis; but occasionally it is so much so, 

 that the two seem to make but one muscle, and have, therefore, 

 been called Sterno-abdominalis, by Rosenmuller. 



SECT. II. MUSCLES AND FASCIJE OF THE ABDOMEN. 



Between the most superficial of the abdominal muscles, which 

 is the external oblique, and the skin, is found the Fascia Super- 

 ficialis Abdominis. In lean subjects it is very distinct, but in 

 fat ones not so much so, from being blended with adipose mat- 

 ter. The laminae of it which are next to the muscles, are kept, 

 in the latter case, rather more free from fat than the more su- 

 perficial. It consists of condensed cellular substance, with very 

 little fibrous matter in it, and may be considered as taking its 

 origin on the front of the thigh,* and extending in front of the 

 abdominal muscles, as high up as the thorax: indeed, if we are 

 disposed to trace it to its whole extent, there is no difficulty in 

 following it over the front of the thorax; thence to the neck, as 



* This statement of origin is to be viewed merely as an anatomical license for 

 descriptive purposes; the most natural line of origin is the whole length of the 

 linea alba, and this same line might be considered as going along the front of 

 the sternum for the pectoral fascia, and along the middle of the neck for its fascia 

 iiiperficialis and profunda. 





