134 THE CAT. [CHAP. v. 



The ntyfo-(/l-os8ii8 (*ty-g) is very large. It arises from the stylo-liyal 

 (and the ligament connecting it with the tympano-hyal), and the 

 stylo-maxillary ligament, and thence passes to the side of the tongue. 



The stylo-phart/ngcns arises from the stylo-hyal and tympano- 

 hyal, and passes thence to the side of the pharynx. 



The mylo-hyoid is a flat muscle which passes from the inside of 

 the mandible to the body of the hyoid. It unites with its fellow of 

 the opposite side (in the middle line, beneath), the two together 

 forming the muscular floor of the mouth. 



The gcnio-hyoid is narrow, and goes from inside the mandible, near 

 the symphysis to the basi-hyal. 



The genio-hyoglossus is a flat, more or less triangular muscle which 

 arises from inside the mandibular symphysis, and is inserted in a 

 radiating manner from beneath the tongue towards its tip back to 

 the basi-hyal. 



The hyoglossus is also a flat muscle passing upwards from each 

 thyro-hyal to the side of the tongue. 



The thyro-hyal muscle is a flattened longitudinal one which unites 

 the thyro-hyal with the chain of ossicles intervening between the 

 tympano-hyal and basi-hyal. 



The stemo-hyoid arises on the deep (or inner) surface of the 

 sternum, and is inserted into the basi-hyal (St. hy). 



The fsterno-t/iyroid, arising close to the last noticed, is inserted into 

 the thyroid cartilage of the larynx (St. th).^ 



The thyro-hyoid is, as it were, a continuation of the sterno- 

 thyroid, and proceeds on each side from the thyroid cartilage of the 

 larynx to the thyro-hyal (Fig. 45, ty). 



These three last muscles all tend, directly or indirectly, to draw 

 back the hyoid. 



The sicrno-mastoid (Fig. 79, St. m) arises from the side of the 

 manubrium (beneath the anterior part of the pectoralis major), and 

 passing forwards and upwards is inserted into the side of the skull 

 just above the mastoid process. If one sterno-mastoid acts alone, it 

 tends to rotate the muzzle towards the opposite side. If both act 

 together, they tend to depress the head as a whole, and somewhat 

 tilt up the muzzle. 



The clcido-mastoid arises from the clavicle, and is inserted into the 

 mastoid process on the ventral side of the insertion of the more 

 superficially passing sterno-mastoid. 



The scalenus secutidus lies deeply at the side of the neck. It arises 

 from the transverse processes of the 3rd, 4th, 5th, 6th, and 7th 

 cervical vertebra?, and is inserted into the first rib (Fig. 79, sc 2 ). 



The scalcmis primm (very much longer) arises mainly by strong 

 but delicate tendons from the 4th and 5th cervical vertebras, and 

 is inserted into the 4th, 5th and 6th ribs near the sternum. It 

 comes as it were out from the substance of the scalenus secundus, 

 with which it is closely connected (sc l ). 



The action of the scaleni is to pull the ribs upwards and forwards, 

 and so to help to expand the chest. 



