THE EAR. 



177 



The fibro-cartilage is an oval, elastic plate, of a yellowish colour, 

 and attached by an anterior ligaifient, which is triangular, broad, 

 and strong, to the zygomatic process, and by ihe posterior ligament 

 to the mastoid process. 



The muscles are, the Tuajor helicis^ which is narrow, about half an 

 inch long, thin, and situated at the arched superior and anterior part of 

 the helix, its fibres being vertical. The Tninar helicis is very small, 

 and situated at the inferior and posterior arch of the helix. The 

 tragicus is three-cornered, tolerably thick, with vertical fibres, upon 

 the tragus. The antitragicus is narrow and short, and passes from 

 the antitragicus to the antihelix. The transversus auriculce,^ is trans- 

 verse on the posterior surface of the ear, extending from the con- 

 vexity of the concha to the external part of the antihelix. The 

 dilatator conchce extends from the meatus auditorius to the anterior 

 part of the tragus, which it draws forwards, and thus dilates the 

 concha. The obliquvs aitriculcE is upon the internal surface of the 

 ear, between the elevations of the fossa innominata and the concha. 



The meatus^ is a cartilaginous tube, lining a bony canal, of about 

 one inch in length, narrow in the middle, and curved downwards ; 

 the skin Uning it is covered with hairs, and glands secreting wax. 



The middle ear or tympanum}' is an irregular, bony cavity, in 

 the petrous portion of the temporal bone, and bounded in front by 

 the membrana tympani. It is filled with air, which enters by the 

 Eustachian tube f and contains a chain of small bones, and open- 

 ings into the mastoid cells. 

 ^ Membrana tympani. — The drum of the ear is a thin, semi-tf ans- 



Fig. 155. 



