394 SENSITIVE SYSTEM. 



erected on either side of the summit of the liead, for the purpose 

 of collecting the vibrations of sound. Superiorly, the concha, 

 (which is ordinarily about six inches in length) grows contracted, 

 and terminates in a point : inferiorly, it presents abroad, firm, 

 circular base or root, so connected with the. cranium upon which 

 it rests, as to admit of some considerable extent of sliding mo- 

 tion. Antero-externally, appears the aperture or external orifice 

 of the concha, ovoid in its outline, and of large dimensions, ex- 

 tending from the point down to within an inch of the base : it is 

 broader above than below, and is terminated inferiorly by a 

 rounded angle. Internally, the concha exhibits a capacious cavity, 

 broadly exposed by the external orifice ; but ending below, at 

 the back part, in a sort of chamber or cul-de-sac, in front of 

 which is the funnel-like entrance to the meatus auditorius. The 

 sides of the conchal cavity are marked by several longitudinal 

 grooves or furrows, separated by irregular salient ridges ; and 

 the whole is so thickly clothed with long downy hair that the 

 cavity in some horses seems to be almost choked up by them. 



Compoaition. — The concha is composed of three cartilages, 

 connected and attached by ligaments and muscles, and enveloped 

 within an external and an internal covering of common integu- 

 ment. 



THE CARTILAGES OF THE EAR, fibrous in their struc- 

 ture, are the conchal, the annular, and the scutiform. 



The conchal cartilage (so denominated from its giving 

 shape to the concha) is the largest of the three, constituting the 

 entire upper or trumpet shaped part of the ear. In its detached 

 state it represents a hollow cylinder very obliquely detruncated 

 along its outer side, in which defective part is formed the external 

 orifice. Its superior end or apex runs into a point: the base or 

 inferior part bulges posteriorly, forming the chamber aforemen- 

 tioned ; while anteriorly it is elongated into a bifurcated process 

 of a semicircular form, which assists in the formation of the 

 meatus auditorius. All the muscles but two, moving the ex- 

 ternal ear, are connected with this cartilage*. By them it is at- 

 tached to the cranium, and also, as well as by ligamentous ex- 

 pansion, to the cartilage next to be considered. 



tragus, anlitragus, and lobulu ,• and three cavities, that of the heliv, fossa 

 navicularis, and concha. 



On the present occasion I have (after the manner of the French Anato- 

 mists) adopted the term concha as an appellation for the whole external ear : 

 its literal signification (a shell) bearing out very well this extended appli- 

 cation of it. The general cavity, or interior of the external ear, I call the 

 conchal cavity ; and the cartilage, which more particularly gives this shell- 

 like or trumpet-form to the external ear, the conchal cartilage. 



* Vide page 84, " Auricular Region." 



