1122 



THE ORGANS OF SPECIAL SENSE 



antihelix; this bifurcates above and forms the cmra (crura anthelicis), which en- 

 close a triangular depression, the fossa of the antihelix (fossa triangularis [auric- 

 ulae]). The narrow curved depression between the helix and antihelix is called 

 the fossa of the helix or the scaphoid fossa (scaphd) ; the antihelix describes a curve 



around a deep, capacious cavity, 

 the concha auriculae, which is 

 partially divided into two parts 

 by the crus of the helix (crus 

 helicis), or the commencement of 

 the helix; the upper part is termed 

 the cymba conchae, the lower part 

 the cavum conchae. In front of 

 the concha, and projecting back- 

 ward 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 a deep notch 

 (incisura intertragica), is a small 

 tubercle, the antitragus. Below 

 this is the lobule (lobulus auricu- 

 lae), composed of tough areolar and adipose tissue, wanting the firmness and elas- 

 ticity of the rest of the pinna. Sometimes the lobule does not hang freely, but 

 is adherent. 



INSERTION 



OF SUPERIOR 



AURICULAR 



MUSCLE 



INSERTION 



OF ANTERIOR 



AURICULAR 



MUSCLE 



OBLIQUE 



AURICULAR 



MUSCLE 



CARTILAGE 



OF EXTERNAL 



AUDITORY 



MEATUS 



INSERTION OF 



POSTERIOR 



AURICULAR 



MUSCLE 



TRANSVERSE 



AURICULAR 



MUSCLE 



FIG. 830. The cartilage of the right pinna, isolated, with the 

 muscles, viewed from the inside. (Spalteholz.) 



Where the helix turns downward a small tubercle, tubercle of Darwin (tuberculum auriculae 

 [Darwini]), is frequently seen. This tubercle is very evident about the sixth month of fetal life; 

 at this stage the human pinna has a close resemblance to that of some of the adult monkeys. 



The cranial surface of the pinna 

 presents elevations which correspond 

 to the depressions on its outer surface 

 and after which they are named, c. g., 

 eminentia conchae, eminentia fossae 

 triangularis, etc. 



Structure. The pinna is composed 

 of a thin plate of yellow fibrocartilage, 

 covered with integument and connected 

 to the surrounding parts by the extrinsic 

 ligaments and muscles, and to the com- 

 mencement of the external auditory 

 canal by fibrous tissue. 



The integument is thin, closely ad- 

 herent! to the cartilage, and covered 

 with hairs furnished with sebaceous 

 glands which are most numerous in the 

 concha and scaphoid fossa. The hairs 

 are most numerous and largest on the 

 tragus and antitragus. 



The cartilage of the pinna (cartilago 



auriculae) (Fig. 831 )consists of one single 



piece; it gives form to this part of the ear, and upon its surface are found all the eminences and 



depressions above described. It does not enter into the construction of all parts of the pinna ; thus, 



:>es not form a constituent part of the lobule; it is deficient also between the lamina of the 



tragus and beginning of the crus helix, the notch between them (incisura terminalis auris) being 



filled up by dense fibrous tissue. At the front part of the pinna, where the helix bends upward, 



small projection of cartilage, called the spine of the helix (spina helicis), while the lower 



part of the helix 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 



FISSURA 



AINTITRAGICO- 

 HELICINA 



TRIANGULAR 

 FOSSA 



SPINE OF 

 HELIX 



CRUS OF 

 HELIX 



LAMINA 

 TRAGI 

 INCISURA 

 TERMINALIS 



Aums 



CAUDA OF 

 HELIX 



INCISURA 

 INTERTRAGICA 



ANTITRAGUS 



FIG. 831. The right ear cartilage, isolated, viewed from 

 without. (Spalteholz.) 



