292 TEE MUSCLES. 



5. The zygomaticus, the presence of which is constant in all species. 



6. The small zygomaticus, represented in the Horse by only the small oblique fasciculus 

 sometimes found beueath the zygomaticus. 



The small zygomaticus and the two elevators of the lips are lachrymal muscles; by their 

 simultaneous contraction they express discontent and melancholy. The zygomaticus, on the 

 contrary, is the muscle of laughter ; it draws the commissures of the lips outwards. 



7. The caninus, or dilator naris lateralis of animals, is attached beneath the infra-orbital 

 foramen, and terminates in the skin of the upper lip. 



8. The risorius of Santorini. 



9. The muscle of the chin (jnento-lahialis). 



10. The myrtiformis, or middle anterior of Bourgelat. 



The other facial muscles of Man, whose analogues it is difBcult or impossible to find in 

 animals, are : — 



11. The triangularis of the lips, which is inserted into the anterior face of the inferior 

 maxilla, and is carried upwards to the commissure of the lips. By its contraction it gives the 

 face an expression of melancholy or contempt. 



12. The quadratus menti, which, after been attached to the maxilla within the mental 

 foramen, passes upwards on the skin of the lower lip, which it depresses, and thus contributes 

 to the expression of fear or dismay. 



13. The transversalis nasi {comprei<sor nasi), a muscle which is fixed into the supermaxilla 

 and on the bridge of the nose, where it is confounded with the opposite muscle. 



14. The dilator of the ala of the nostril, a very small triangular fasciculus applied to the 

 external part of the nostril, whicli, by contracting, it elevates. 



3. Muscles of the Lower Jaw. 

 There is nothing remarkable to be noted in tlie masseter, temporal, or pterygoid muscles. 

 The upper belly of the digastricus is not attached directly to the inferior maxilla, as it is in 

 Solipeds. 



4. Hyoideal Muscles, 



These are only three in number : — 



1. The mylo-hyoideus. 



2. The stylo-hyoideus, which commences at the styloid process of the temporal bone, and 

 shows a ring for the tendon of the digastricus. 



3. The genio-hyoideus. 



We do not find in Man the occipito-styloideus, kerato-hyoideus, or the hyoideus-transversus. 



Axillary Region. 



This comprises two muscles, pairs, placed beneath the sternum, in the axilla 

 which terminate on the anterior limb. These are the superficial and deep 

 pectorals} 



Preparation. — 1. Place the animal in the first position. 2. Unfasten one of the forelimbs, 

 and allow it to hang, so as to separate it from the opposite one. 3. Eemove the skin with 

 care, and dissect, on the side corresponding to the detached limb, the two muscles which form 

 the superficial pectoral. 4. Prepare the deep pectoral on the opposite side. To do this, 

 remove the panniculus cautiously, so as not to injure the muscle about to be examined ; divide 

 the superficial pectoral transversely, and turn back the cut portions to the right and left ; divide 

 also the mastoido-humeralis and cervical trapezius near their insertion into the limb, and 

 reflect them upon the neck. 



1. Superficial Pectoral (Pectoralis Anticus and Transversus) 

 (Figs. 174, 9, 10 ; 175, 3). 



Synonyms. — Muscle common to the arm and {orearm— Bourgelat. Pectoralis magnus of 

 Man. (Percivall and Leyh describe three pectorals, others four ; but, as will be seen in this 

 work, the two pectorals are each divided into two portions, which, for practical purposes, agrees 

 with those who describe four. This muscle is the Pectoralis transversus of Percivall. Leyh 



For a justification of the employment of tliese new denominations, see the note at p. 230. 



