THE EAR. 



G29 



Fig. 311. The Pinna or Auricle. 

 Outer Surface. 



ovoid form, its surface uneven, with its larger end directed upwards. Its outer 

 surface is irregularly concave, directed slightly forwards, 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 pro- 

 minent 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 into two parts, 

 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 innomi- 

 nata seu scaphoidea). The antihelix de- 

 scribes a circuit round a deep, capacious 

 cavity, the concha, which is partially divided 

 into two parts by the commencement of the 

 helix. In front of the concha, and project- 

 ing backwards 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 sepa- 

 rated from it by a deep notch (incisura 

 intertragica), is a small tubercle, the anti- 

 tragus. 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 yellow 

 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 depressions 

 above described. It does not enter into the construction of all parts of the auricle, 

 and presents several intervals or fissures in its substance, which partially separate 

 the different parts. 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. The fissures in the cartilage are the 

 fissure of the helix, 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 yellowish color, and similar in structure to 

 the cartilages of the alaa nasi. 



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. 



Those connecting the various parts of the cartilage together are also two in 



