CHAP, v.] THE CAT'S MUSCLJM. 131 



MUSCLES OF THE HEAD AND BACK. 



7. The platysma myoides is a skin muscle which covers the 

 side ^ of the neck and face. Its facial part invests the bulbs of the 

 vibrissaB and long hairs of the eye-brows. 



The orbicularis oris is a sphincter muscle, its fibres extending 

 round the mouth in the substance of the lips. The fibres of the 

 upper and lower lip meeting at a symphysis at each angle of the 

 mouth. It is very slightly developed, and is much interrupted 

 medianly above, because the cat's upper lip is divided medianly 

 into two lobes. 



The orUcularis palpcbrarum is a thin muscle, the sphincter of the 

 eye-lids, as it surrounds the eye beneath the skin. It is not attached 

 to any bone except at the inner margin of the orbit, and its fibres 

 are arranged concentrically so as to close the eyelids by their con- 

 traction. This muscle adheres intimately to the skin. 



The occipito-frontalis is a thin, flat muscle, one portion of which 

 is attached to the fascia of the occiput and temporal region, the other to 

 the frontal region, and is connected with the orbicularis palpebrarum. 



The levator labii supcrioris alcequc nas-i is a rather large flat muscle 

 which is connected above with the frontal portion of the foregoing, and 

 thence descends to the upper lip and angle of the orbicularis oris. 



The lemtor anguli oris (Fig. 77, c) is a small fleshy mass which arises 

 beneath the infra-orbital foramen and descends to the outer ala of the 

 nose and upper lip. 



The pyramidalis passes downwards from the frontal to the dorsum 

 of the nose. 



Compressor nans. This is a very faintly-marked muscle of fibres 

 extending transversely over the cartilages of the nose. 



The zygomaticus (z) is a small muscle extending downwards from 

 the malar close to the maxilla (when it is continuous with the zygo- 

 mato-auricularis) to the orbicularis oris, near the angle of the mouth. 



The myrtiformis is a triangular, rather large muscle extending from 

 the firm tissue enclosed in the upper lip to the side of the nose (my}. 



The cat's ears are very movable, and can be strongly drawn back 

 and folded down close to the head. 



A variety of small muscles are inserted into the cartilage of the 

 external ear, or into a narrow, elongated cartilage called the scuti- 

 form cartilage, which extends on the surface of the head obliquely 

 forwards and inwards in front of each ear, and slides over the 

 aponeurosis of the temporal muscle. 



Thefronto-auricular (fa) is a small muscle extending from the 

 orbit to the ear. 



Another is the temporo- auricular (to) which extends (beneath the 

 front auricularis) from the hinder side of the orbit to the antitragus.* 



The maxillo- auricular (mo), slender and vertical, extends from the 

 mandible behind the condyle to the outer side of the base of the concha. 



* For an explanation of the parts of the ear, see Chapter IX., 26. ^ 



Iv 



