628 THE EAPt. 



concha, surroimds the Tipper and posterior margin of the auricle, and 

 gradually loses itself in the back part of the lobule.* Within the helix 

 is another curved ridge, the antilielix (3), which, beginning below at the 

 antitragus, sweeps round the hollow of the concha, foi'ming the posterior 

 boundary of that concavity, and is divided superiorly into two diverging 

 ridges. Between the helix and the antihelix is a narrow curved groove, 

 the fossa of the helix (fossa innominata, scaphoidea) (2) ; and in the 

 fork of the antihelix is a somewhat triangular depression, i\\Q fossa of 

 the antilielix (fossa triangularis vel ovalis) (4). 



Strtictnre. — The pinna consists mainly of yellow fibro-cartilage 

 and integument, with a certain amount of adipose tissue. It has 

 several ligaments and small muscles of minor importance. 



The slmi covering it is thin, closely adherent to the cartilage, and 

 contains sebaceous follicles, which are most abundant in the hollows of 

 the concha and scaphoid fossa. 



The cartilage (figs. 442, 443) forms a thin plate, presenting all the 

 inequalities already described as apparent on the outer surface of 

 the pinna, and on its cranial surface having prominences the reverse 

 of the concha and the fossa of the hehx, while between these is a 

 depression in the situation of the antihelix. The cartilage is not 

 confined to the pinna, but enters likewise into the construction of 

 the outer part of the external auditory canal. When dissected from 

 other structures, it is seen to be attached by fibrous tissue to the rough 

 and prominent margin of the external auditory meatus of the temporal 

 bone. The tubular part is cleft in front from between the tragus 

 and fore part of the helix inwards to the bone, the deficiency being 

 filled with fibrous membrane ; the whole cartilage may be looked 

 upon as an elongated plate, the lower part of which is folded round 

 in front so as to bring it nearly into contact with the upper part. 

 There is no cartilage in the lobule : it contains only f;it and tough 

 connective tissue. Behind the prominence of cartilage which forms 

 the antitragus is a deep notch, separating it from the cartilage of the 

 helix, which here forms a tail-like process descending towards the 

 lobule (fig. 443). At the fore part of the pinna, opposite the first bend 

 of the helix, is a small conical projection of the cartilage, called the 

 process of the helix, to which the anterior ligament is attached. Behind 

 this process is a short vertical slit in the helix ; and on the surface of 

 the tragus is a similar but somewhat longer fissure. A deep fissure 

 passes back between the commencement of the helix and the tube of 

 the ear, and another passing outwards and backwards from the deep 

 end of the longitudinal cleft separates the part forming the tragus from 

 the rest of the tube, so that the tube is continuous with the pinna only 

 by means of a narrow isthmus. One or two other irregular gaps or 

 fissures partially divide the cartilaginous tube transversely, and the 

 whole of these deficiencies are termed fissures of Santorini. The sub- 

 stance of the cartilage is very pliable, and is covered by a firm fibrous 

 23erichondrium. 



Of the ligaments of the 2nnna, the most important are two, winch 



* A slight pointed projection which is occasionally observed in the human subject at 

 the margin of the helix (at a place indicated by the asterisk in fig. 441) is of interest 

 as representing the much more distinct pointed extremity met with in the expanded ears 

 of quadrupeds (Darwin, "The Descent of Man," 2nd edition, p. 15). The point in 

 question happens to be distinctly seen in the cartilage represented in fig. 442. 



