EXTERNAL EAR. 



361 



the varied impressions arising from the different varieties 

 of color, and its optic nerve accurately to transmit those 

 impressions to the brain or FIG. 105. 



mind; so in the ear we have an 

 organ having special relation 

 with sound, an auditory nerve, 

 sensible to all the impressions 

 of the varied sonorous vibra- 

 tions, and a capacity for con- 

 ducting those impressions to 

 the brain, or common sensori- 

 um, where perception of their 

 presence occurs, and where the 

 mind forms an estimate of their 

 value. The ear is usually di- 

 vided into three portions, an 

 external, middle, and internal 

 portion. 



The external ear, (called pinna or auricle?) situated, as is 

 well known, at the side of the head, and between the mas- 

 toid and squamous portions of the temporal bone, consists 

 of the pinna and external meatus. 



The pinna presents a number of eminences and depres- 

 sions, forming folds and hollows, constituting a very irregu- 

 lar surface, and all having special names assigned them. 

 The superior folded border is called helix, (f^t, a fold.) The 

 projecting eminence below this is the anti-helix. The de- 

 pression between the two is called the fossa innominata. 

 The pointed projection looking backward and overhanging 

 the nieatus as a valve, is called the tragus (?payo$, a goat,) 

 from having hairs supposed to resemble the goat. Just 

 opposite to this there is another eminence called the anti- 

 tragus. The upper extremity of the anti-helix divides into 

 two crura, leaving a triangular space between them, called 

 scaphoid or navicular fossa. 



FIG. 105 represents the external Ear. a a Helix. 666 Anti-helix, c 

 Scapha or fossa navicularis. d d Fossa innominata. e Tragus. /Antitragus. 

 g Lobulus. h Concha, i Meatus auditorius externus. 



