ORGAN OF HEARING. 



551 



like a valve. The posterior margin of the 

 tragus, and anterior margin of the antitragus, 

 meet inferiorly ; but superiorly they are sepa- 

 rated by a considerable notch. Bounded by 

 the anthelix, tragus, and antitragus, and tra- 

 versed horizontally by the commencement of the 

 helix, is a deep cavity, called concha, at the an- 

 terior part of which is the auditory passage 

 leading from it, as the pipe from the mouth of a 

 funnel. The lower pendulous part of the ear is 

 called lobule. 



Fig. 253. 



a. b. c. d. e. the helix ; 

 f. g. the upper and lower 

 crura of the anthelix ; h. 

 the point of junction of 

 the two crura ; '. k. the 

 anthelix ; I. tragus ; m. 

 antitragus ; n. lobule ; o. 

 navicular fossa ; p. fossa 

 innominata ; q. cavity of 

 the concha ; r. entrance 

 of the auditory passage. 



The auricle of the left side (reduced in size}. ( From 

 Soemmerring.) 



Stripped of the skin which invests it, the 

 auricle is found to be composed of a cartila- 

 ginous skeleton, on which its elasticity depends. 

 The skeleton presents, with some modifications, 

 all the eminences and depressions we have de- 

 scribed, except the lobule, which consists merely 

 of a prolonged fold of skin, between the layers 

 of which is cellular and adipose tissue. 



In the skeleton of the auricle, the helix com- 

 mences by an acute point in the excavation 

 of the concha. Gradually becoming broader 

 and more elevated, it proceeds obliquely up- 

 wards and forwards, then turning round the 

 upper margin of the ear, contracts in breadth ; 

 and about the middle of the posterior margin, 

 its hemlike fold having ceased, its simple edge 

 is continued into a free tail-like process of car- 

 tilage, which is separated by a fissure from the 

 antitragus. On the anterior part of the helix 

 above the tragus, there is a mammillary process 

 of cartilage which gives attachment to a liga- 

 ment. Behind and below the root of this 

 mammillary process, there is a small vertical 

 fissure in the helix, incisura helicis. 



Regarding the anthelix there is little more to 

 be said, except that the lower branch of its 

 upper extremity forms a very prominent crest ; 

 and that inferiorly the anthelix is continued into 

 the same tail-like process that the helix runs 

 into, and is also partly continued into the anti- 

 tragus. 



The antitragus is a small plate of cartilage, 

 forming an angle, directed upwards and forwards. 

 It is continuous by its base with the cartilage 

 of the concha. The lobule hangs from the 

 antitragus, and the tail-like process of cartilage 

 common to the helix and anthelix. 



Tragus. Between the helix and tragus there 

 is no connexion by cartilage. The space is 

 merely filled by a continuation of the fibrous 

 cellular tissue which constitutes the upper and 

 posterior part of the cartilaginous and mem- 

 braneous portion of the auditory passage. 



The cartilage of the ear is covered by peri- 

 chondrium, which imparts considerable strength 

 to it. When the perichondrium is removed by 

 dissection, the cartilage is found to be very 

 brittle. 



Fig. 254. 



a. a. a. a. helix ; b. ant- 

 helix ; c. two crura of 

 anthelix d. cavity of the 

 concha ; e. antitragus ; 

 f. tragus ; g. fissure be- 

 tween the tragus and 

 commencement of carti- 

 laginous portion of the 

 auditory passage, the 

 larger fissure of Santo- 



Skeleton of the cartilage of the external ear (dimi- 

 nished). (From Soemmerring.) 



The skin covering the cartilage of the ear 

 adheres intimately to its unequal surface, less 

 so to its back and circumference. The lower 

 part of the hem-like fold of the helix is formed 

 entirely by it; also the lobule, as has been 

 already said. The skin of the auricle contains 

 a number of sebaceous follicles, particularly in 

 the concha, and around the entrance of the au- 

 ditory passage. 



On the tragus is observed, especially in old 

 people, a small tuft of hair, which has been 

 compared to a goat's beard ; whence the name 

 lragus,(rgayo$,hircus,) which the Germans trans- 

 late Bock. The antitragus they call Gegenbock. 



Ligaments of the ear. Anterior ligament, 

 (ligamentum auricula anterius). This proceeds 

 from the root of the zygomatic process to the 

 lower and anterior part of the helix, and to the 

 tragus. 



Posterior ligament, (ligamentum auricula 

 posterius). Extends from the outer surface of 

 the mastoid process to the posterior surface of 

 the cartilage of the ear, where the concha runs 

 into the auditory passage. Besides the above 

 ligaments binding the ear to the head, there are 

 others which extend from one point of the car- 

 tilage of the ear to another. 



Muscles of the ear. The muscles of the ear 

 fall into two classes : viz. those which, arising 

 from the head, are inserted into the ear, and 

 move it as a whole ; and those which, extend- 

 ing from one part of the cartilage to another, 

 are calculated, were they strong enough, to pro- 

 duce a change in the general form of the auricle. 



Muscles which move the ear as a whole, or the 

 extrinsic muscles. The elevator, or superior 

 muscle of the ear, (M. attollens auriculam s. 

 superior auricula), is a broad thin muscle, 

 composed of fibres spread out on the upper part 

 of the side of the head. It arises from the 

 middle part of the epicranial aponeuroses, and 

 also from the temporal aponeuroses ; thence, to 

 its insertion into that elevation of the ear-carti- 

 lage on the surface next the head, which cor- 

 responds to the fossa innominata, the fibres be- 

 come more aggregated, so that the muscle is 

 much narrower, but thicker inferiorly than su- 

 periorly. By elevating the upper part of the 



