THE EXTERNAL EAR. 1485 



surface are represented by eminences. Thus, the concavity of the concha is 

 represented on the cranial surface by the eminentia conchae ; the antiheHx by 

 the fossa antihelicis ; the fossa triangularis by the eminentia fossae triangu- 

 laris ; the scaphoid fossa, by the eminentia scaphae. The other elevations and 

 depressions corresponding to those of the outer surface are not seen on the cranial 

 surface, except in the dissected cartilage denuded of the integument. 



Structure of the Auricle. — The auricle consists of integument and an enclosed 

 plate of yellow elastic cartilage continuous with that of the meatus. It is also provided 

 with several unimportant ligaments and muscles. The lobule, however, contains no 

 cartilage, but only fibrous tissue and fat enclosed within the integumentary fold. 



The skin of the auricle is thin and closely adherent to the cartilage, especially 

 on the outer surface. In certain parts it contains fine hairs and sebaceous and sweat 

 glands. The hair follicles are especially abundant over the tragus, antitragus and 

 the notch lying between them, the hairs guarding the entrance into the external 

 auditory canal, known as tragi, being exceptionally long. The sebaceous glands 

 are especially well developed in the cavity of the concha. 



Cartilage of the Auricle. — The cartilage of the auricle may be divided into 

 two parts : (a) the scroll-like plate forming the tragus and external auditory canal, 

 and {b) the large irregular plate forming the main cartilage. These two divisions 



Fig. 1244. 



Insertion of auricularis superior Obliquus 



Helicis majoj 



Spina helicis 



^^^^'^^^ J£!H WJHHI^^^ Insertion of 



Plate of tragus W^^^JB^IK' auricularis 



and external \^^Sm9'- Posterior 



auditory canal \3k^!S^S^^^^r 



'om^t^^^ ^^ Cauda helicis 



Cartilaginous framework of right auricle, with intrinsic auricular muscles; A., outer, 5, inner surface. 



are connected by a cartilaginous isthmus lying between the incisura intertragica on 

 its outer side and the deep fissure, (incisura terminalis auris), which in the isolated 

 cartilage is seen between the posterior wall of the outer meatus and the anterior 

 border of the lower part of the concha, on its inner side. Two smaller clefts, the 

 fissures of Santorini, are found between the three plates which form the carti- 

 laginous scroll supporting the tragus and outer end of the external auditory canal. 

 The cartilage of the tragus is an irregular plate and subject to considerable variation. 



The depressions and elevations of the cartilage proper correspond in general to 

 the surface modelling of the auricle, but are sharply marked, especially on the cranial 

 aspect. A deep notch, the fissura antitragohelicina, separates the lower part of 

 the helix from the antitragus, thus defining the caudal process (cauda helicis), as 

 the lower extremity of the cartilage forming the helix is called. 



The spina helicis is a small conical projection, directed forward and down- 

 ward, opposite the first bend of the helix. This serves for the attachment of the 

 anterior ligament. The upper end of the tragus-plate fits into an angle formed by 

 the junction of the beginning of the helix and the upper end of the anterior border of 

 the concha. In addition to the elevations and depressions already referred to, on 

 the mesial surface is found a ridge, the ponticulus, which extends downward 

 and forward over the eminence of the concha and serves for the attachment of the 

 posterior auricular muscle (Fig. 1244, B^. 



