130 SUPERIOR LABIAL GROUP. 



5. Superior Labial Group. Orbicularis oris, 



Levator labii superioris alseque nasi, 



Levator labii superioris proprius, 



Levator anguli oris, 



Zygomaiicus major, 



Zygomaticus minor, 



Depressor labii superioris alseque nasi. 



The ORBICULARIS ORIS is a sphincter muscle, completely surroundin 

 the mouth, and possessing consequently neither origin nor insertion, 

 is composed of two thick semicircular planes of fibres, which embrace the 

 rima of the mouth, and interlace at their extremities, where they are con- 

 tinuous with the fibres of the buccinator, and of the other muscles con- 

 nected with the angle of the mouth. The upper segment is attached by 

 means of a small muscular fasciculus (naso-labialis) to the columna of the 

 nose ; and other fasciculi connected with both segments and attached to 

 the maxillary bones are termed " accessorii." 



Relations. By its superficial surface with the integument of the lips, 

 with which it is closely connected. By its deep surface with the mucous 

 membrane of the mouth, the labial glands and coronary arteries being 

 interposed. By its circumference with the numerous muscles which move 

 the lips, and by the inner border with the mucous membrane of the rima 

 of the mouth. 



The LEVATOR LABII SUPERIORIS AL^QUE NASI is a thin triangular 

 muscle : it arises from the upper part of the nasal process of the superior 

 maxillary bone ; and becoming broader as it descends, is inserted by two 

 distinct portions into the ala of the nose and upper lip. 



Relations. By its superficial surface with part of the orbicularis palpe- 

 brarum muscle, the facial artery, and the integument. By its deep surface 

 with the superior maxillary bone, compressor nasi, alar cartilage, and 

 with a muscular fasciculus attached only to the bone, and thence called 

 musculus anomalus. 



The LEVATOR LABII SUPERIORIS PROPRIUS }$ a thin quadrilateral mus- 

 cle : it arises from the lower border of the orbit, and passing obliquely 

 downwards and inwards, is inserted into the integument of the upper lip ; 

 its deep fibres being blended with those of the orbicularis. 



Relations. By its superficial surface with the lower segment of the 

 orbicularis palpebrarum, with the facial artery, and with the integument. 

 By its deep surface with the origins of the compressor nasi and levator 

 anguli oris muscle, and with the infra-orbital artery and nerve. 



The LEVATOR ANGULI ORIS arises from the canine fossa of the superior 

 maxillary bone, and passes outwards to be inserted into the angle of the 

 mouth, intermingling its fibres with those of the orbicularis, zygomatici, 

 and depressor anguli oris. 



Relations. By its superficial surface with the levator labii superioris 

 proprius, the branches of the infra-orbital artery and nerve, and inferiorly 

 with the integument. By its deep surface with the superior maxillary bone 

 and buccinator muscle. 



The ZYGOMATIC muscles are two slender fasciculi of fibres which arise 

 from the malar bone, and are inserted into the angle of the mouth, where 

 they are continuous with the other muscles attached to this part. The 

 xy^omaticus minor is situated in front of the major, and is continuous at 



