EPICRANIAL AND AUEICULAR MUSCLES. 265 



parts. The frontalis has been found to send slips of attachment to the frontal; 

 nasal, or superior maxillaiy bones, and occasionally to the tendo oculi or to the 

 tipper end of the levator labii superioris alaique nasi. 



A pair of symmetrical musculai- slips is very frequently observed extending 

 outwards from the occipital protuberance, generally on the surface of the trape- 

 zius, but sometimes underlying that muscle, and inserted variously into the 

 posterior auricular or sterno-mastoid muscles, or into the outer part of the occi- 

 pital bone. This pair of muscular slips has received the name of f;ww.s(vr.v//.v 

 niK'lue. 



Actions. — By the contraction of the combined occipito-frontales muscles, the 

 scalp is drawn backwards, and the eyebrows elevated ; by the contraction of the 

 f rontales muscles alone, the eyebrows are elevated, the scalp pulled forwards, and 

 the skin of the forehead thrown into transverse wrinkles ; by the contraction of 

 the occix>itales muscles alone, the scalp is drawn backwards ; and by the alternate 

 action of the occipitales and frontales muscles the scalp is moved backwards and 

 forwards. In the majority of persons, however, there is only a partial control 

 over the action of these muscles, limited to the elevation of the eyebrows and 

 horizontal wrinkling of* the forehead. 



AURICUIiAR MUSCLES 



Besides minute bundles of muscular fibres which jiass from one part 

 of the auricle to another, and which will be most conveniently described 

 along with that structure, there are attached to the external ear three 

 larger, but still very slightly developed, muscles, which serve to move it 

 as a whole. 



The auricularis superior or attolleixs auricuiam, the largest of 

 the three, arises in the temporal region of the head from the epicranial 

 aponeurosis. Its fibres are extremely delicate, and converge from a 

 wide surface to be inserted by a compressed tendon into the cartilage 

 of the ear at the upper and anterior part of the helix and upper part 

 of the concha. 



The auricularis anterior or attrahens auricuiam, scarcelj' sepa- 

 rated from the preceding muscle, is pale and indistinct, and is attached 

 to the thin lateral prolongation of the epicranial aponeurosis, from 

 which it passes backwards to be inserted into the fore part of the 

 helix. 



The auricularis posterior or retrahens auricolaiu muscle, con- 

 sists of two or three ftisciculi, which arise from the mastoid process by 

 short aponeurotic fibres, and are inserted into the back part of the 

 concha. The fibres are deeper in colour and more distinctly marked 

 than in either of the other auricular muscles. 



Varieties. — Of the auficular muscles the posterior and the anterior are subject 

 to greater varieties than the superior, but all vary somewhat in the extent of 

 their development, the posterior more frequently by an increase in the number 

 of its slips, the anterior by a diminution of the volume and distinctness of its 

 fibres. The posterior fibres of the attollens have been observed continued back 

 into the occipitalis. 



Actions. — The three auricular muscles respectively draw the pinna of the ear 

 upwards, backwards, and forwards. In the majority of persons theii- action is 

 not directly under voluntary control, 



MUSCLES OP THE EYELIDS AND EYEBROWS, 



These are four in number — namely, the orbicularis palpebrarum 

 and tensor tarsi, the levator palpebral superioris, and the corrugator 

 supercilii. 



