THE EXTERNAL EAR. 



1487 



a branch, the anterior artery of the lobule, from the artery of the tragus. The pos- 

 terior auricular artery supplies a variable number of branches to the auricle. Usually 

 two of these are given off below and one above the posterior auricular muscle. These 

 branches are larger and longer than those from the superficial temporal. After rami- 

 fying over the cranial surface of the auricle, they reach its outer surface by piercing 

 the auricle or by passing over its free margin. They supply the posterior part of 

 the outer surface and anastomose with the branches of the superficial temporal. 



The veins of the auricle accompany the arteries and include : (a) the anterior 

 auricular, which empties into the superficial temporal ; (b) the posterior auricular, 

 three or four in number, which join a plexus behind the ear which empties principally 

 into the external jugular vein, but also unites with the posterior facial vein. Com- 

 munications with the mastoid emissary vein of the lateral sinus also frequently exist. 



The Lymphatics. The lymphatics of the auricle form a close net- work within the 

 deeper layers of the integument, from which lymphatic stems pass in three general 

 groups. Those from the outer surface are afferents chiefly of the anterior auricular 

 nodes, which are placed immediately in front of the tragus and beneath the parotid 

 fascia ; a few, however, bend backward over the helix to end in the posterior auricu- 



FIG. 1246. 



( A. perforans 

 fossae triangularis 



A. helicis 



A. temporal is 



A. perforans 

 cymbse 



A. caudae helici 



A, tragi 



A. auricularis 

 post. sup. 



Posterior 

 auricular muscle 



A. auricularis 

 post. inf. 



A. auricularis 

 posterior 



Parotid branch 

 Arteries of right auricle, A, lateral surface; B, postero-mesial surface. (Schwalbe.) 



lar nodes that overlie the insertion of the sterno-mastoid muscle. Those from the 

 upper part of the cranial surface pass mainly to the posterior auricular nodes, some 

 being tributary to the external jugular nodes. A number of stems from the lower 

 part of the auricle and from the lobule terminate in the parotid nodes. 



Nerves of the Auricle. The motor nerves supplying the intrinsic muscles 

 of the auricle are from the temporal and posterior auricular branches of the facial 

 nerve, the former being distributed to the muscles of the helix, tragus and antitragus, 

 whilst the posterior auricular supplies the tranverse and oblique muscles. The sen- 

 sory nerves include branches from : (a) the great auricular nerve, which supplies the 

 integument of the lower three-quarters of the inner surface of the auricle, with the 

 exception of a small portion near the meatus, and sends filaments to the outer surface 

 of the lobule and adjacent area ; (3) the small occipital nerve, which supplies the 

 upper one-quarter of the inner surface ; (<r) the auricular branch of the vagus, which 

 supplies the small muscles on the back of the concha and a limited cutaneous area 

 near the meatus ; and (d^ the auriculo-temporal nerve, which divides at the level of 

 the tragus, and sends filaments from its auricular branches to the outer surface of the 

 auricle. 



THE EXTERNAL AUDITORY CANAL. 



The external auditory canal (meatus acusticus) leads from the cavity of the 

 concha to the tympanic membrane, which closes its inner extremity. Although the 

 adult meatus varies considerably in size and direction, it is usually tortuous. 



In a general way, in its external portion the canal extends somewhat forward 

 and inward, perhaps slightly upward ; then, in its middle portion, almost directly 



