MYOLOGY i6i 



an aesthetic point of view, to the modelHng of the corre- 

 sponding region of the human body. Such, at least, is our 

 impression. 



Suprahyoid Muscles 



As their name indicates, these muscles are found above 

 the hyoid bone ; amongst those which should arrest our 

 attention for a moment are the mylo-hyoid and the digastric. 



Mylo-hyoid. — This muscle, forming a sort of fleshy sling 

 which contributes in great measure to form the floor 

 of the mouth, is situated between the lateral halves of 

 the inferior maxillary bone. Arising on each side from the 

 internal oblique line of the mandible, its fibres are directed 

 towards the median line, to be inserted posteriorly into the 

 hyoid bone, and, between this bone and the anterior part of 

 the mandible, into a median raphe which unites these latter. 



Digastric. — This muscle arises from the styloid process 

 of the occipital bone and from the jugular process ; it 

 thence passes downwards and forwards, and terminates 

 variously, in different species. In the ox and the horse it 

 terminates in its anterior portion on the internal surface 

 of the inferior maxillary bone, close to the chin. But 

 in the horse a bundle of fibres is detached from the upper 

 portion of the muscle, to be inserted into the recurved 

 portion of the jaw. It is to this fasciculus that Bourgelat 

 has given the name of ^stylo-maxillary muscle.'' 



In the pig, dog, and cat, the digastric differs more from 

 the corresponding muscle in man ; it is not, as in the latter, 

 formed of two parts. The anterior portion only exists. 

 This consists of a thick muscular mass, which is inserted into 

 the middle of the internal surface of the lower jaw. 



In the dog and cat it is clearly recognisable in the super- 

 ficial layer of muscles by the long and thick prominence 

 which it produces below the masseter, against the inferior 

 border of the mandible (see pp. 235 and 237, the two figures 

 showing the myology of the head of the dog). 



By its contraction, it draws the lower jaw downwards and 

 backwards. 



II 



