MUSCLES OF THE TRUNK. 279 



expansion of the cartilaginous septum of the nose which projects laterally beyond 

 the nasal spine. These fibres abut, by their most eccentric extremities, against 

 the skin of the false nostril and the appendix of the inferior turbinated bone. 



To this muscle we may attach the small muscular fasciculus which Bourgelat 

 has described as the anterior intermediate. To study it, it is necessary to raise 

 the upper lip and remove the mucous membrane lining it. It is then seen that 

 its fibres, attached to the inner side of the premaxilla, above the incisor teeth, 

 ascend to meet those of the dilatator naris superior, and to terminate with them 

 on the anterior appendix of the inferior turbinated bone ; some fibres become 

 lost in the lips. 



The dilatator naris superior acts as an external dilator of the nostril and false 

 nostril. (Percivall names it the depressor labii superioris.) 



11. Transversalis Nasi (Dilatator Naris Transversalis). 



{Synonym. — Dilatator naris anterior — Percivall). 



This muscle is in two parts : one, inferior, single, short, and quadrilateral, 

 flattened on both sides, lies on the wide part of the nasal cartilages, forming 

 transverse fibres ; the other, superior, pair muscle, formed of pale short fibres 

 passing from the thin portion of the septum nasi which is laterally bordered by 

 the nasal prolongation, to the skin of the false nostril and appendix of the upper 

 turbinated bone. Covered by the skin and the aponeurotic expansion of the two 

 elevator muscles of the upper lip, the transverse muscle of the nose covers the 

 cartilages to Avhich it is attached, and is confounded below with the orbicularis 

 of the lips. 



Designed to bring together the two internal alte of the nose, this muscle 

 ought to be considered more particularly as the dilator of the nostrils ; and, in 

 addition, as an internal dilator of the false nostril. 



B. Palpebral Region. 



This region includes three muscles which act upon the eyelids or the sldn 

 in proxindty to the orbit ; these are the Orbicularis Palpebrarum, Fronto- 

 palpebral {Corrugator Supercilii), Lachrymalis. 



1. Orbicularis of the Eyelids (Orbicularis Palpebrarum) (Fig. 168, 6). 



This muscle is a thin wide sphincter common to the two eyelids, and lying 

 on the palpebral fibrous plate and the bones forming the margin of the orbit. 

 Its external surface is covered by the skin, to which it adheres very closely. A 

 small tendon wliich extends from the lachrymal tubercle to the nasal angle of the 

 eye, is considered as the origin of the fibres of this muscle ; some of these — 

 the most numerous— pass upwards and are distributed in a circular manner in 

 the upper eyelid ; the others reach the lower eyelid and rejoin the numerous ones 

 towards the temporal angle of the eye. 



The contraction of this muscle determines the occlusion of the palpebral opening. 



2. Fronto-Palpebral, or Corrugator Supercilii (Fig. 168, 2). 



This is a short flat muscle, arising from the external surface of the frontal 

 bone, and passing downwards and outwards to mix its fibres with those of the 

 orbicularis at the supra-orbital foramen, which it covers, and the skin of the eye- 

 brow. It has been erroneously considered as an elevator of the upper eyelid. When 



