500 



DISSECTION OF THE HEAD. 



Incisions. 



Muscles of 

 the ear. 



Dissection 

 of upper 

 muscles, 



of posterior 

 muscle. 



Attrahens 



aureni 



muscle. 



Attollens 



aurem 



muscle. 



Retrahens 

 aurem con- 

 sists of two 

 or three 

 bundles. 



Use of ear 

 muscles. 



along the upper border of the zygomatic arch and along the upper 

 margin of the orbit as far as the root of the nose. A second incision 

 should pass from the root of the nose, over the skull in the middle 

 line to the external occipital protuberance behind. The flap of 

 skin should be reflected upwards from below in front of the pinna 

 and then be turned downwards behind that part as far as the 

 superior curved line of the occipital bone. 



EXTRINSIC MUSCLES OF THE EAR. Three muscles pass to the 

 auricle from the side of the head. Two are above it, one elevat- 

 ing, the other drawing it forwards ; and the third, a retrahent 

 muscle, is behind the ear. There are other special or intrinsic 

 muscles of the cartilage of the ear, which will be afterwards 

 noticed. 



Dissection. If the auricle be drawn downwards by hooks, the 

 position of the upper muscle will be indicated by a slight prominence 

 between it and the head. By cleaning the slight ridge thereby 

 produced, and removing a little areolar tissue, a thin fan-shaped 

 layer of pale muscular fibres will come into vie\v, the anterior 

 portion of which is the attr aliens, while the posterior is the attollens 

 aurem muscle (fig. 185). 



On drawing forwards the ear, a ridge marks the situation of the 

 posterior muscle, and the retrahens muscle must be sought beneath 

 the subcutaneous tissue. It consists of rounded bundles of fibres, 

 and is stronger and deeper than the others. 



The ATTRAHENS AUREM (fig. 185, 16 ) is a small fan-shaped muscle 

 which arises from the fore part of the aponeurosis of the occipito- 

 frontalis. Its fibres are directed downwards and backwards, and 

 are inserted into a projection on the front of the rim of the ear. 

 Beneath it are the superficial temporal vessels and nerves. 



The ATTOLLENS AUREM (fig. 185, 15 ) has the same form as the 

 preceding, though its fibres are longer and better marked. Arising 

 also from the tendon of the occipito-frontalis, the fibres converge 

 to their insertion into the inner or cranial surface of the pinna of 

 the ear into an eminence corresponding with a fossa (that of the 

 antihelix) on the opposite aspect. 



The RETRAHENS AUREM (fig. 185, 17 ) consists of two or three 

 roundish but separate bundles of fibres, which are stronger than 

 those of the other muscles. The bundles arise from the root of the 

 mastoid process, and pass almost horizontally forwards to be 

 inserted by tendinous fibres into the lower part of the ear (concha) 

 on its cranial aspect. The auricular branches of the posterior 

 auricular artery and nerve are in contact with this muscle. 



Action. The three preceding muscles will move the outer ear 

 slightly in the directions indicated by their names ; the anterior 

 drawing it upwards and forwards, the middle one upwards, and the 

 posterior backwards. 



Dissection. The muscular fibres of the occipitalis behind and 

 of the frontalis in front are now to be cleaned according to their 

 direction (fig. 185) and then the superficial vessels and nerves dis- 

 played in the following manner (fig. 186, p. 505). 



