OCCIPITO-FROXTALIS 



427 



cervical plexus, too;ether with tlic masscter, and buccinator, the muscles of the 

 front and side of the neck, and the pectoralis major and deltoid. 'Its anterior 

 border lies externally to the sterno-clavicular Joint, and is often conspicuous in 

 the aged, in whom the two muscles may be seen to hang, like a dewlap, beneath 

 the chin, and then to divide into the two separate folds formed by their internal 

 borders, which run outwards and downwards towards the clavicles. 



Variations. — The anterior bonier of" tlie mu.scle may be placed as fiir backwards as the middle 

 of the clavicle, and in some cases the muscle has been entirely absent. Slips have been seen 

 going to the side of the thyroid cartilage, the auricle or the mastoid process. 



Fig. 309. — The Supekficiai. jMuscles of the Head axd Neck. 



Epicranial 

 aponeurosis 



Orbicularis palpebrarum 



Pyramidalis 



Levator labii superioris 

 aleeque nasi 

 Compressor narium 



Dilatator naris anterior 

 Dilatator naris posterior 



Levator labii superioris 



Zygomaticus minor 



Levator anguli oris 

 Orbicularis oris 



Depressor labii inferioris 

 Depressor anguli oris 



Attollens 

 aurem 



[|, I Attrahens 

 ^ aurem 



Occipitalis 



^ Retrahens 



aurem 



Trapezius 





2. OCCIPITO-FROXTALIS 



The occipito-frontalis — named from its two muscular bellies. Avhich cover 

 ])arts of the occipital and frontal bones — consists of two curved muscular sheets 

 united by a strong a])oncurosis. and is best described in three parts — viz. the 

 occipitalis and frontalis muscles and the epicranial aponeurosis. 



( 1 ) The occipitalis is a small (luadrilateral sheet. 



Origin. — ( 1 j The outer two-thirds of the superior nuchal line of the occipital 

 bone, and (2) a ridge upon the mastoid process. 



