THE MUSCLES OF THE AIR PASSAGES. 4!) 



while its lower apex is inserted into the posterior 

 extremity of the second half-ring. To do this it must 

 be evident that it lies obliquely across the larynx. 



35. TJie bronchialis anticus has much the same form 

 as the last muscle, but is fully double its size. It is 

 crossed at its origin by the broncho-trachealis anticus, 

 which must be pulled to one side in order to examine it. 

 We find that its superior apex arises from the last 

 ring of the trachea, from which point the fibres pass 

 obliquely forwards to become inserted by a lower apex 

 into the rim of the arytenoid cartilage of the lower 

 larynx, and the anterior extremities of the first and 

 second half-rings. 



36. Either sterno-trachealis is represented by a deli- 

 cate little cord of muscular fibres, which arise on the 

 side of the trachea beneath the hinder border of 

 the broncho-trachealis anticus, and pass directly out- 

 wards, a little downwards and backwards, across 

 the cavity of the chest, to become inserted on the 

 inner aspect of the corresponding costal process of the 

 sternum, rather in advance of its centre. A delicate 

 band of fascia spans the insertion of this muscle a few 

 millimetres in front of its point of attachment. This is 

 shown in Fig. 19. According to Owen, "this is the 

 most constant of all the muscles affecting the lower 



O 



larynx. It is reckoned by Savart as the sixth pair of 

 vocal muscles, but not by Cuvier, since it is not directly 

 attached to any part of the lower larynx, and exists in 

 birds, as, e.g., the Vulture and Ostrich, in which that 

 larynx is not developed " (Anat. Verts., vol. ii. p. 224). 



The infinite number of changes that the foregoing 

 muscles can bring about in the form of an organ so con- 

 stituted as the inferior larynx of the Raven is, can be 

 more easily imagined than described. The principal 



E 



