THE EXTERNAL EAR. 



695 



numerous eminences and depressions which result Fig. 376. The Pinna, or Au- 

 from the foldings of its fibro-cartilaginous element. ricle - Outer Surface. 



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 anti- 

 helix; this bifurcates above, so as to inclose a 

 triangular depression, the fossa of the antihelix. 

 The narrow curved depression between the helix 

 and antihelix is called the fossa of the helix (fossa 

 innominata, f. scaphoidea}. The antihelix describes 

 a curve round a deep, capacious cavity, the concha, 

 which is partially divided into two parts by the 

 commencement of the helix. In front of the con- 

 cha, and projecting backwards over the meatus, 

 is a small pointed eminence, the tragus ; so called 

 from its being generally covered, on its under sur- 

 face, 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, composed of 

 tough areolar and adipose tissues, wanting the firmness and elasticity of the 

 rest of the pinna. 



Structure of the pinna. The pinna is composed of a thin plate of }^ellow 

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

 ligaments, and a few muscular fibres. 



The integument is thin, closely adherent to the cartilage, and furnished with 

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



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 depres- 

 sions 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 defi- 

 cient, also, between the tragus and beginning of the helix, the notch between 

 them being filled up by dense fibrous tissue. It presents several intervals of 

 fissures in its substance, which partially separate the different parts. The 

 fissure of the helix is a short, vertical slit, situated at the fore part of the pinna, 

 immediately behind a small conical projection of cartilage, opposite the first 

 curve of the helix (process of the helix). Another fissure, the fissure of the 

 tragus, is seen upon the anterior, surface of the tragus. The antihelix is 

 divided below, by a deep fissure, into two parts; one part terminates by a 

 pointed, tail-like extremity (processus caudatus)] the other is continuous with 

 the antitragus. The cartilage of the pinna is very pliable, elastic, of a yellow- 

 ish color, and similar in structure to the cartilages of the nose. 



The ligaments of the pinna consist of two sets. 1. Those connecting it to 

 the side of the head. 2. Those connecting the various parts of its cartilage 

 together. 



The former, the most important, are two in number, anterior and posterior. 

 The anterior ligament extends from the process of the helix to the root of the 

 zygoma. The posterior ligament passes from the posterior surface of the concha 

 to the outer surface of the mastoid process of the temporal bone. A few fibres 

 connect the tragus to the root of the zygoma. 



The ligaments connecting the various parts of the cartilage together are 

 also two in number. Of these, one is a strong fibrous band, stretching across 

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

 front, and partly encircling the boundary of the concha; the other extends 

 between the concha and the processus caudatus. 



The nwscles of the pinna (Fig. 377), like the ligaments, consist of two sets; 



