MUSCLES OF THE TRUNK. 



27$ 



each other at the commissures of the mouth, and confounded with the superficial 

 layer of the buccinator, which they appear to continue, these two muscular por- 

 tions also receive a large portion of the fibres belonging to the majority of the 

 extrinsic muscles, such as the dilatator naris lateralis and levator labii superioris 

 alfequi nasi. 



The orbicularis is not attached to the neighbouring bone ; its component 

 fibres, affecting a circular form, have, consequently, neither beginning nor ending, 

 except in being continuous with other fibres. 



The internal face of the superior fasciculus responds to a layer of salivary 

 glands, which in part separate it from the buccal mucous membrane. The external, 

 covered by the skin, adheres to it in the most intimate manner, and is found 

 isolated from it only on the median line, at first by the aponeurotic expansion of 



Fig. 168. 



SUPERFICIAL MDSCLES OF THE FACE AND HEAD. 



1, Temporo-auricularis externus, or attollens maximus ; 2, levator palpebrae, or corrugator super- 

 cilii; 3, temporo-auricularis internus, or attollens posticus; 4, 5, zygomatico-auricularis, or 

 attollens anticus ; 6, orbicularis palpebrarum; 7, abducens, or deprimens aurem ; 8, parotid 

 gland; 9, temporal, or subzygomatic vein; 10, ditto, artery; 11, 12. superior and inferior 

 maxillary nerves- 13, fascia of the masseter muscle; 14, nasal bones; 15, supernasol-abialis, or 

 levator labii superioris alseque nasi; 16, supermaxillo-labialis, or nasalis longus labii superioris; 

 17, external maxillary or facial artery; 18, facial vein; 19, supermaxillo-nasalis magnus, or 

 dilatator naris lateralis ; 20, superior maxillary nerve ; 21, zygomatico-labialis, or zygomaticus ; 

 22, parotid, or Steno's duct ; 23, masseter ; 24, alveolo-labialis, or buccinator ; 25, super- 

 maxillo-nasalis parvus, or nasalis brevis labii superioris ; 27, labialis, or orbicularis oris ; 28, 

 maxillo-labialis, or depressor labii inferioris ; 29, mento-labialis, or levator menti. 



the nasalis longus, then by a musculo-fibrous layer analogous to that which forms 

 the levator menti. 



By its internal face, the inferior fasciculus likewise responds to the buccal 

 mucous membrane, and to some salivary glands. By its external face, it forms 

 an intimate union with the cutaneous integument, like the superior fasciculus. 



This muscle plays the part of a constrictor of the anterior opening of the 

 mouth, and has complex functions to perform in suction, the prehension of food, 

 and in mastication. 



2. Zygomatico-labialis (Zygomaticus) (Fig. 168, 21). 



Synonyms. — Portion of the cuticularis of Bourgelat. The zygomaticus major of Man. 



A very small, pale, and thin ribbon-like muscle, arising from the surface of 

 the masseter, near the maxillary spine, by an aponeurosis which is confounded 

 with the panniculus ; it terminates on the surface of the buccinator, at a short 



