MUSCULAR SYSTEM. 93 



NASALIS 15REVIS LABII SUPERIORIS. 



Super-maxillo-iiasalis parvus. 



Situation. — Behind the external nares. 



Figure. — Narrow, thin, forming two sides of a triangle. 



Attachments. — Inferiorly, to the superior and anterior maxil- 

 lary bones, and to the suture uniting them ; superiorly, to the os 

 nasi ; in the middle to the horn or cornet of the nose and the skin 

 of the false nostrils : it forms, in fact, a fleshy investment to the 

 angular bony boundary of the false nostrils. 



Relations. — Externally, with the levator labii superioris alaque 

 nasi, the tendon of the nasalis longus labii superioris, and the 

 skin ; internally, with the membrane of the nose. 



Direction. — Transverse, inclining forwards. 



Structure. — Fleshy. 



DEPRESSOR LABII SUPERIORIS. 



Situation. — Side of the upper jaw. 



Figure. — Broad, thin, irregular. 



Attachment. — Inferiorly to the alveoli of the lateral and middle 

 incisores, extending thence along the side of the jaw as far as the 

 tusk ; superiorly, it is confounded with the glandular substance 

 of the upper lip, and is also connected with the inferior nasal 

 cartilages. 



Relations. — Anteriorly, with the labial gland, and, at the side, 

 with the nerves descending from the pes anserinus ; posteriorly, 

 with the front of the jaw; superiorly, with the cartilages of the 

 nose; inferiorly, with the incisor teeth. 



Direction. — Oblique, from before backwards, and from below 

 upwards. 



Structure. — Fleshy. 



Action. — To draw down the side of the lip, and with it the nasal 

 cartilage, and thereby have some effect in dilating the nostril. 



ORBICULARIS ORIS. — LabiuHs. 



Situation. — Within the border of the lips, of which it consti- 

 tutes the principal thickness. 



Figure. — It forms two semi ovals, directed backwards, united 

 at the commissures of the lips. 



Attachments. — To the glandular substance and skin of the 

 li])s, and more particularly at the commissures, where the fibres 

 coming from both lips cross one another, and become confounded 

 with those of other muscles inserted thereabouts. 



