450 THE EXTERNAL EAR. 



The circumference of the ear is formed by a fold of the mar- 

 gin of the cartilage : and this folded edge is denominated Helix, 

 from its winding direction. It commences in the cavity called 

 Concha, to be presently described ; and, after proceeding for- 

 wards and upwards, it turns round backwards and downwards. 



Within this prominent margin is a second prominence, called 

 the Antihelix, which appears to be formed by a convexity of 

 the surface of the cartilage, but is found in every ear. It is 

 nearly semicircular, with its concavity towards the meatus ; 

 and it forms the margin of the cavity called Concha, above 

 mentioned. The upper portion of the antihelix consists of the 

 two superficial ridges, which unite after forming between them 

 a shallow depression, the Fossa Navicularis or Scapha. 



The helix and antihelix form, therefore, three cavities or 

 depressions, viz. 1. A sulcus, occasioned by the fold of the 

 helix, which is sometimes called Fossa innorninata. 2. The 

 Fossa Navicularis ; and 3. The Concha, which may be con- 

 sidered as the proper orifice of the ear. 



Besides these prominences and fossae there are two other 

 eminences, called Tragus and Antitragus, formed, also, by 

 this cartilage. The Tragus is anterior to the meatus audito- 

 rius, and covered by a continuation of the skin of the face. 

 It projects backwards, so as partly to cover the meatus. On 

 the inside of it there is commonly a tuft of hair, from which 

 its name is derived. 



The Antitragus is opposite to the tragus, on the posterior 

 margin of the concha. 



On the posterior surface of the ear the convexity of the 

 concha is very conspicuous. 



When the skin and cellular membrane is carefully removed, 

 and the cartilaginous skeleton of this structure is examined, 

 its form will not appear so regular as that of the undissected 

 ear • for there are several deficiencies or vacuities in it ; the 

 most remarkable of which is between the tragus and the helix. 



The cartilage thus formed is attached to the bones of the 

 face and cranium, by three ligamentous membranes, which 

 connect it to the zygomatic and the mastoid processes of the 



