22 ELEMENTARY PHYSIOLOGY. [l. 



b. The stemo-thyroid lying laterally of (a) and 

 for the greater part of its course close to it, 

 it runs from the sternum to the thyroid 

 cartilage of the larynx. 



c. The thyro-hyoid, a small muscle running 

 from the thyroid cartilage to the hyoid bone, 

 in the upper part of its course it lies lat- 

 erally of (a). 



d. The sterno-cleido-mastoid lying laterally of 

 (b) and covering it near the hyoid bone, 

 thence it proceeds outwards, and disappears 

 under a white oval mass, the submaxillary 

 glands. 



These muscles may be dissected in the rab- 

 bit also, the representative of the sterno- 

 cleido-mastoid has however no clavicular 

 attachment and hence is called the sterno- 

 mastoid, it does not come in contact with 

 the submaxillary gland. 



29. Carefully separate the sterno-mastoid from the 

 sterno-thyroid ; the sympathetic-pneumogastric 

 trunk and the carotid artery will come into 

 view. 



Observe the following points in which the dog 

 differs from the rabbit : 



a. There is but one superior vena cava form- 

 ed by the junction of the two innominate 

 veins. 



(The arrangement of the main arteries is usually 

 that described above for the rabbit, but con- 

 siderable variations occur.) 



