MUSCLES OF MOUTH. 



37 



The CORRUGATOR SUPERCILH is beneath the orbicularis, near the inner 

 angle of the orbit. Its fibres arise from the inner part of the superciliary 

 ridge of the frontal bone, and are directed outwards to join the orbicular 

 muscle about the middle of the orbital arch. It is a short muscle, and is 

 distinguished by the closeness of its fibres. 



Action. It draws inwards and downwards the mid-part of the eyebrow, 

 wrinkling vertically the skin near the nose, and stretching that outside its 

 point of insertion. 



MUSCLES OF THE MOUTH. The muscles of the aperture of the mouth 

 consist of a sphincter ; an elevator of the upper lip and angle of the mouth ; 

 an elevator and depressor of the lower lip and angle of the mouth ; and 

 retractors of the corner. Lastly, a wide muscle of the cheek closes the 

 space between the jaws. 



Fig. 6. 



Occipito-frontalis, anterior belly. 



4. Posterior belly. 

 Orbicularis palpebrarura. 

 Levator labii superioris alseque 



nasi. 



Compressor nasi. 

 Levator labii superioris. 

 Zygomaticus minor (too large). 

 Zygomaticus major. 

 Risorius. 

 Masseter. 

 Orbicularis oris. 

 Depressor labii inferioris. 

 Depressor anguli oris. 

 Buccinator. 

 Levator anguli oris. See fig. 1. 



The ORBICULARIS ORIS MUSCLE (fig. 6, u ) surrounds the opening of 

 the mouth, and is united with the several muscles acting on that aperture. 

 It consists of two parts, inner and outer, which differ in the appearance 

 and arrangement of the fibres, like the sphincter muscle of the eyelids. 



The inner part (fig. 5, 7 ), whose fibres are pale in color and fine in 

 texture, forms a rounded thick fasciculus, which corresponds with the red 

 margin of the lip. The fibres of this portion of the muscle, unattached to 

 bone, blend with the buccinator at the corner of the mouth, and some pass 

 from lip to lip. 



The outer part is thin, wide, and more irregular in form, and is con- 

 nected with the subjacent bone, besides its union with the adjacent muscles. 

 In the upper lip it is attached, on each side of the middle line, by one 

 slip (naso-labial) to the back of the septum of the nose (fig. 5, T ) ; and by 

 a thin stratum to the outer surface of the upper jaw, opposite the canine 

 tooth, and external to the depressor of the wing of the nose. In the 



