THE EAR. 849 



upward. Its outer surface is irregularly concave, directed slightly forward, and 

 presents numerous eminences and depressions which result from the foldings of its 

 fibre-cartilaginous element. To each of these, names have been assigned. Thus 

 the external prominent rim of the auricle is called the helix. Another curved 

 prominence, parallel with and in front of the helix, is called the antihelix ; this 

 bifurcates above, so as to enclose a triangular depression, the fossa of the antihelix 

 (fossa triangularis). The narrow curved depression between the helix and anti- 

 helix is called the fossa of the helix (Scapha); the antihelix describes a curve 

 round a deep, capacious cavity, the concha, which is partially divided into two 

 parts by the cms helicis or the commencement of the helix ; the upper part is 

 termed the cymba concha;, the lower part the cavum concha. 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 

 a deep notch (incisura inter tragic a) is a small tubercle, the antitragus. Below this 

 is the lobule, composed of tough areolar and adipose tissue, wanting the firmness 

 and elasticity of the rest of the pinna. Where the helix turns downward a small 

 tubercle, the tubercle of Darwin, is frequently seen. This tubercle is very evident 

 about the sixth month of foetal 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, e. g., eminentia 

 conchae, eminentia triangularis, etc. 



Structure of the Pinna. The pinna is composed of a thin plate of yellow fibro- 

 cartilage, covered with integument, and connected to the surrounding parts by the 

 extrinsic ligaments and muscles ; and to the commencement of the external audi- 

 tory canal by fibrous tissue. 



The integument is thin, closely adherent 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 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 auricle : 

 thus it does not form a constituent part of the lobule ; it is deficient also between 

 the tragus and beginning of the helix, the notch between them being filled up by 

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

 is a small projection of cartilage, called the 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 carti- 

 lage of the pinna presents several intervals or fissures in its substance which par- 

 tially separate the different parts. The fissure of the helix is a short vertical slit, 

 situated at the fore part of the pinna. Another fissure, the fissure of the tragus, is 

 seen upon the anterior surface of the tragus. The cartilage of the pinna is very 

 pliable, elastic, of a yellowish color, and belongs to that form of cartilage which is 

 known under the name of yellow fibro-cartilage. 



The ligaments of the pinna consist of two sets: 1. The extrinsic set, or those 

 connecting it to the side of the head. 2. The intrinsic set, or those connecting the 

 various parts of its cartilage together. 



The extrinsic ligaments, the most important, are two in number, anterior and 

 posterior. The anterior ligament extends from the spina helicis and tragus to 

 the root of the zygoma. The posterior ligament passes from the posterior sur- 

 face of the concha to the outer surface of the mastoid process of the temporal 

 bone. 



The chief intrinsic ligaments are: (1) a strong fibrous band, stretching acros 

 from the tragus to the commencement of the helix, completing the meatus in front, 

 and partly encircling the boundary of the concha; and (2) a band which extends 

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