MUSCLES OF THE NOSTRILS 



217 



the facial vessels, and branches of the facial nerve ; deeply, the mucous membrane 

 of the mouth and the inferior buccal glands. 



Blood-supph/. — P'acial and l)UCcinator arteries. 



Nerve-supply. — Facial nerve. 



MUSCLES OF THE NOSTRILS 



1. Levator nasolabialis. — This has been described (p. 214). 



2. Dilatator naris lateralis (M. caninus).— This thin, triangular muscle lies 

 on the lateral nasal region, and passes between the two branches of the levator 

 nasolabialis. 



Origin. — The maxilla, close to the anterior extremity of the facial crest. 

 Insertion. — The outer wing of the nostril. 



Fig. 174. — Nasal and Superior Labial Muscles op Horse. 



a, a', Dilatator naris transversus; b, levator labii superioris proprius; b', tendon of b; b" , common tendon of 



two levatores labii superioris proprii; c, c', dilatator naris inferior; d, e, dilatator naris superior;/, orbicularis oris; 



g, levator nasolabialis, a portion of which is removed; /i, dilatator naris lateralis (cut); /, cornu of alar cartilage; 



A, nostril; it', false nostril; /, nasal diverticulum; ?/;, nasal bone. (After EUenberger-Baum, Top. Anat. d. Pferdes.) 



Action. — To dilate the nostril. 



Structure. — The muscle has a flat tendon of origin, passes between the two 

 branches of the levator nasolabialis, and spreads out in the external wing of the 

 nostril. The lower fibers blend with the orbicularis oris. 



Relations. — Superficially, the skin, fascia, and the labial branch of the levator 

 nasolabialis; deeply, the maxilla and the nasal branch of the levator nasolabialis. 



Blood-supply. — Facial artery. 



Nerve-supply. — Facial nerve. 



3. Dilatator naris transversus (M. transversus nasi). — This is an unpaired, 

 quadrilateral muscle, which lies between the nostrils. It consists of two layers. 



Attachments. — Superficial layer, the superficial faces of the laminae of the alar 

 cartilages; deep layer, the convex edges of the cornua of the same. 



Action. — To dilate the nostrils. 



