HEARING. 255 



189. The external ear consists of two parts, the pinna and 

 the canal. The pinna, or that part which is understood when 

 the ear is spoken of as a feature, presents various named 

 inequalities of surface. The outer border, which extends 

 round the back, and curves inwards in front, is called the 

 helix; the elevation within it. forked at the upper part, is 

 the anti helix ; while the hollow at the bottom of which the 

 canal is placed is called the cup or concha. The little eleva- 

 tion in front of the canal is called the tragus, the similar 

 elevation behind is called the antitragus, and the pendulous 

 part is the lobule. The pinna consists of a framework of 

 "cartilage covered with integument; but at the lower end of 

 the helix, the cartilage comes to a point, and in the lobule 

 there is nothing but a mass of firm adipose tissue. The 

 lobule is sometimes absent, and is a human peculiarity, the 

 "beautifully rounded ears of monkeys having none. The 

 pinna, in many animals, is obviously useful as an ear 

 trumpet for gathering sonorous vibrations; but in man it is 

 of comparatively little service, although it is provided with 

 muscles which give it a slight degree of movement. One of 

 these muscles passes from the parts in front, another from above, 

 and a third from the mastoid process behind, to be attached 

 near the root of the pinna; and they are named,, respectively, 

 the attrahenSj attollens, and retrahens auriculam muscles. 

 There are likewise various still smaller muscles which pass 

 from one part of the pinna to another ; thus, one bundle on 

 the tragus, and another on the antitragus, pull these eminences 

 very slightly downwards and apart; two slips are placed on 

 the fore part of the helix, and the antihelix and its inferior 

 branch are each crossed by short fibres on their cranial sur- 

 face; but the only interest connected with these muscles is, 

 that they represent more important structures in the lower 

 animals. So also there is a little tubercle often present near 

 the upper part of the margin of the helix, which is interest- 

 ing as being the alleged representative of the tip of the ear 

 in animals which have the pinna pointed (Darwin). 



The canal or external auditory meatus of the ear, about 

 an inch and a quarter in length, is partially bounded in its 

 outer part by cartilage, continuous with that of the pinna; 

 but ? more deeply, for more than half its length, has osseous 



