154 THE ARTISTIC ANATOMY OF ANIMALS 



aponeurosis of this latter attached to the zygomatic crest. 

 This latter part is considered by some writers as forming 

 a portion of the panniculus muscle of the neck. 



In the horse it is attached to the angle of the lower jaw 

 by a tendon, which an aponeurosis that passes under the 

 parotid gland binds to the mastoido-humeral muscle and 

 the mastoid process. 



By reason of this insertion into the jaw, in the case of 

 the solipeds, this muscle is further named the sterno- 

 maxillary. 



When it contracts, it flexes the head, and inclines it 

 laterally. This movement is changed to direct flexion when 

 the two sterno-mastoid muscles contract simultaneously. 



In man, the sterno-cleido-mastoid and the trapezius 

 leave a triangular space between them, which, being limited 

 inferiorly by the middle third of the clavicle, is known as 

 the supraclavicular region ; this region , being depressed, 

 especially in its inferior part, has also been given the name 

 of supraclavicular fossa — popularly called the ' salt-cellar.^ 



The muscles which form the floor of this region, passing 

 from above downwards, are : a very small portion of 

 the complexus, splenius, levator anguli scapulae, posterior 

 scalenus, and anterior scalenus ; then, crossing these latter, 

 and most superficial, is the omo-hyoid muscle. 



An analogous region, but of only slight depth, exists in 

 quadrupeds ; its borders are formed by the mastoido-humeral 

 and trapezius muscles. 



It is not limited below by the clavicle — we know, indeed, 

 that this, or the intersection which represents it, belongs 

 to the mastoido-humeral muscle — but by the inferior portion 

 of the spine of the scapula. 



It is of greater or less extent according to the species 

 considered. 



In the dog, cat, pig, and ox, it is narrow, for the muscles 

 which bound it approach one another pretty closely. It has, 

 as in man, the form of a triangle, with the apex above. 

 In the horse it is much broader, and, contrary to the 

 arrangement which it presents in the human species, the 

 widest part is directed upwards. 



