1034 ORGANS OF THE SENSES AND THE COMMON INTEGUMENT 



this divides above into two crura, between which is a triangular depression, the 

 fossa triangularis. The narrow-curved depression between the helix and the antihelix 



is called the scapha ; the antihelix describes a curve 

 around a deep, capacious cavity, the concha, which is 

 partially divided into two parts by the cms or com- 

 mencement of the helix; the upper part is termed the 

 cymba conchse, the lower part the cavum conchae. 

 In front of the concha, and projecting backward over 

 the meatus, is a small pointed eminence, the tragus, 

 so called from its being generally covered on its under 

 surface with a tuft of hair, resembling a goat's beard. 

 Opposite the tragus, and separated from it by the 

 intertragic notch, is a small tubercle, the antitragus. 

 Below this is the lobule, composed of tough areolar 

 and adipose tissues, and wanting the firmness and 

 elasticity of the rest of the auricula. 



The cranial surface of the auricula presents ele- 

 vations which correspond to the depressions on its 

 lateral surface and after which they are named, 

 e. a., eminentia conchae, eminentia triangularis, 



Fia. 904. The auricula. Lateral , 



surface. etC. 



Structure. The auricula is composed of a thin plate of yellow fibrocartilage, covered with 

 integument, and connected to the surrounding parts by ligaments and muscles; and to the com- 

 mencement of the external acoustic meatus by fibrous tissue. 



The skin is thin, closely adherent to the cartilage, and covered with fine hairs furnished with 

 sebaceous glands, which are most numerous in the concha and scaphoid fossa. On the tragus 

 and antitragus the hairs are strong and numerous. The skin of the auricula is continuous with 

 that lining the external acoustic meatus. 





Spina helicis 4 



Cartilage of 

 meatus 



Sulcus antihelicis transversua 



Eminentia conchae 



Ponticulus 

 Cauda hclicis 



FIG. 905. Cranial surface of cartilage of right auricula. 



The cartilage of the auricula (cartilago auriculae; cartilage of the pinna) (Figs. 905, 906) con- 

 sists of a single piece; it gives form to this part of the ear, and upon its surface are found the 

 eminences and depressions above described. It is absent from the lobule; it is deficient, also, 

 between the tragus and beginning of the helix, the gap being filled up by dense fibrous tissue. 

 At the front part of the auricula, where the helix bends upward, is a small projection of cartilage, 

 called the spina helicis, while in the lower part of the helix the cartilage is prolonged downward 

 as a tail-like process, the cauda helicis; this is separated from the antihelix by a fissure, the 

 fissura antitragohelicina. The cranial aspect of the cartilage exhibits a transverse furrow, the 

 sulcus antihelicis transversus, which corresponds with the inferior crus of the antihelix and 

 separates the eminentia conchse from the eminentia triangularis. The emhientia conchee is 

 crossed by a vertical ridge (ponticulus) , which gives attachment to the Auricularis posterior 



