THE EXTERNAL EAR 



fluid gathers beneath and flows over the lids, the condition is known as epiphora or stillicidium. 

 This latter condition is set up by some obstruction to the nasal duct frequently occurring in tuber- 

 culous subjects. In consequence of this the tears and mucus accumulate in the lacrimal sac, 

 distending it. Suppuration in the lacrimal sac (dacryocystitift) is sometimes met with; this 

 may be the sequel of a chronic inflammation; or may occur after some of the eruptive fevers 

 in cases where the lacrimal passages were previously quite healthy. It may lead to lacrimal 

 fistula. 



THE EAR (ORGANON AUDITUS). 



The organ of hearing is divisible into three parts the external ear. the middle 

 ear or tympanum, and the internal ear or labyrinth. 



THE EXTERNAL EAR (AURIS EXTERN A). 



The external ear consists of an expanded portion named pinna or auricula, and 

 the auditory canal or meatus. The former serves to collect the vibrations of the air 

 by which sound is produced; the latter conducts those vibrations to the tympanum. 



DARWINIAN 

 TUBERCLE 



FOSSA 

 TRIANGULARIS 



CHURA OF 

 ANTIHELIX 



CRUS OF 

 L/HELIX 



INCISURA 

 ANTERIOR 



TUBERCULUM 

 SUPRATRAGICUM 



EXTERNAL 

 AUDITORY 

 MEATUS 



NlNCISURA 

 , INTERTRAGICA 



POSTERIOR 



AURICULAR 



SULCUS 



CAVUM CCNCHAE 



FIG. 829. The right pinna, viewed from without. (Spalteholz.) 



The Pinna, or Auricula (Fig. 829), is attached to the side of the head midway 

 between the forehead and occiput. It is of an ovoid form, with its larger end 

 directed upward. Its outer surface is irregularly concave, directed slightly for- 

 ward, and presents numerous eminences and depressions which result from the 

 foldings of its fibrocartilaginous element. To each of these, names have been 

 assigned. Thus, the external prominent rim of the auricle is called the helix. 

 Another curved prominence, parallel with and in front of the helix, is called the 



71 



