76 



THE EAR. 



Vessels of the pinna (fig. 84). The auricular branch of the posterior auricular 

 artery, a branch from the external carotid, is distributed chiefly on the mesial surface, 

 but some of its branches turn over the folded margin to reach the external surface 

 of the helix : others pierce the cartilage and ramify on the external surface of the 

 anthelix, concha and lobule. Besides this artery, the auricle receives the anterior 

 auricular branches from the superficial temporal. These chiefly supply the anterior 

 part of the lobule, the tragus, and the anterior part of the helix. 



The veins for the most part accompany the arteries. They join the posterior 

 auricular and temporal veins, but some enter the mastoid emissary vein of the 

 lateral sinus (see Vol. II., p. 526). The lymphatics of the pinna pass partly 

 forwards from the concha to join a gland in front of the tragus ; partly downwards 

 and backwards from the upper and posterior part of the pinna towards the mastoid 

 glands ; and partly downwards from the lobule towards the parotid lymphatic 

 glands. 



Nerves. The great auricular nerve, from the cervical plexus, supplies the 

 integument of the greater part of the inner surface of the auricle, and sends small 

 filaments with the posterior auricular artery to the outer surface of the lobule and 



attrahens 

 aurem 8 7 



rctrahens 

 6 aurem 



\ \ 



3 10 1 2 



Fig. 84. ARTERIES SUPPLYING THE AURICLE. (Testut.) 



10 



1, external carotid ; 2, internal maxillary ; 3, superficial temporal ; 4, transverse facial ; 5, middle 

 temporal ; 6, orbital branch of temporal ; 7, anterior terminal branch ; 8, posterior terminal branch ; 

 9, anterior auricular branches ; 10, posterior auricular artery ; 11, its mastoid branch ; 12, perforating 

 branches. 



the part of the ear above it. The auricular branch of the posterior auricular nerve, 

 derived from the facial, after communicating with the auricular "branch of the 

 pneumogastric, ramifies on the back of the ear, supplying the small muscles. The 

 auricula-temporal branch of the third division of the fifth nerve gives filaments 

 chiefly to the outer surface of the pinna. A branch of the small occipital supplies 

 the upper part of the inner surface. Filaments from the temporal branches of the 

 facial supply the external muscles. 



THE EXTEBNAL AUDITORY CANAL. 



The external auditory canal, meatus auditorius externus (85, 2, 2), extends 

 from the bottom of the concha to the membrane of the tympanum and serves to 

 convey the vibrations of sound to the middle chamber of the ear. The canal is 



