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ANATOMY OF VERTEBRATES. 



The 'Icvator labii superioris/ fig. 29, I, arises from the lower 

 maririn of llie orbit, and descends to be inserted into the orbi- 



o 



cularis and the skin of the upper lip. The ' levator anguli oris,' 

 fig. 29, c', arises below the snborbital foramen and descends, 

 inclining outward, to the angle of the mouth, blending its fibres 

 with those of the zygomatici and orbicularis. The f zygomaticus 

 major,' fig. 29, 3, is cylindrical, rising from the malar and de- 

 scending obliquely inward to a similar insertion at the angle of the 

 month. The zygomaticus minor, fig. 29, 3, arises in front of the 

 xyg. major, and passing downward and inward to the angle of 

 the mouth, where it is continuous with the outer margin of the 

 levator labii superioris. The levator menti is a conical fasciculus 

 arising from the incisive fossa of the mandible, external to the 

 symphysis, and expanding as it descends to be inserted into the 

 integument of the skin. The ' depressor labii inferioris,' fig. 30, 

 d, arises from the inner half of the external oblique line of the 

 mandible, and is partly also continued from the platysma : its 

 fibres ascend, inclining inward to be attached to the lip, where 

 they blend with those of the orbicularis oris. The ( depressor 

 anguli oris,' fig. 29, t, arises from the external oblique line of the 

 mandible : its fibres ascend and converge to the angle or commis- 

 sure of the lips, blending with the other insertions at that part. 



The buccinator, fig. 30, b, arises from both upper and lower 

 jaws and the ptery go-maxillary ligament : its fibres line 

 the cheek and converge toward the angle of the mouth, where 

 some decussate, the lower ones going to the upper segment of 



the orbicularis, the upper ones to 

 the lower segment, while other 

 fibres are continued forward into 

 the corresponding lip. The buc- 

 cinator acts, in antagonism with 

 the orbicularis, in spirting fluids 

 from the mouth and in playing on 

 wind instruments. In mastication 

 the buccinator presses the food from 

 between the cheek and gums into 

 the cavity of the mouth. It assists 

 also in deglutition when the mouth 

 is closed, by pressing the food back- 

 ward. The ' levator labii superioris 

 alaeque nasi ' arises from the nasal 

 process of the maxillary, descends 

 obliquely outward and divides, a short strip being attached to 



30 



