THE MUSCLES. 131 



168. 7. Zygomaticus major, greater zygomatic muscle. 



Pos. : oblique ; external and below the last described ; covered 

 below by the fat of the cheek, above by orbicular palpebr. Or.: 

 os zygomatic. Ins. : the angle of the mouth. Act. : draws the 

 angle of the mouth outwards and upwards. 



169. 8. Depressor anguli oris (s. triangularis menti}. 



Pos. : beneath the skin at the sides of the chin ; covers the qua- 

 drat, menti internally, the buccinator externally. Or.: broad, 

 from basis maxill. infer. Ins. : pointed, to the angle of the mouth 

 (levator anguli and zygomatic. major). Act.: draws the angle 

 of the mouth outwards and downwards (physiognomy of the sim- 

 pie). 



170. 9. Risorius (Santorini], laughter muscle, thin, three- 



sided. 



in the fat of the cheeks, upon m. platysmam. Or.: fascia mas- 

 seter. Ins. : m. zygomatic. major. Act. : draws the inferior 

 internal part of the cheeks outwards and upwards, so that (in 

 laughing) a small fossa is formed in the skin. 



171. 10. Depressor labii inferioris (s. quadratus menti). 



Pos. : close beneath the skin of the chin, covers the sphincter 

 oris and lev. menti. Or.: the inferior border of the chin. Ins.: 

 the under lip. Act. : draws the under lip downwards, both to- 

 gether stretch it. 



172. 11. Levator menti. 



Pos.: in the chin, bounded above by the sphincter oris, covered 

 externally by quadratus; in the centre the fibres of both sides pass 

 over, above, in an arched manner, into one another; below, they 

 are united by firm fibro-cellular tissue, and free. Or.: below the 

 corner tooth of the lower jaw. Ins.: skin and fat of the chin. 

 Act.: draws the skin of the chin upwards, corrugates it, and 

 pushes up the lower lip. Its most superior fibres (m. incisivus 

 inferior) penetrate the under lip, and are said to compress it 

 against the gums. 



173. 12. Transversalis menti, wanting in feeble subjects. 



Pos. : transverse below the free border of the chin, upon m. pla- 

 tysmam. Or.: continuation of triangularis menti. Ins.: the 

 internal angle of both mm. triangulares. Act. : stretches the 

 skin on the chin. 



Nerves: (for three to twelve) facialis ; for the superior muscles; infra 

 orbital, and subculan., for the inferior; mentalis. 



