66 INNERVATION. [CHAP. xvin. 



In examining the anatomy of the human ear, we shall first de- 

 scribe the external ear, next the middle ear, or tympanum, and 

 lastly, the labyrinth. 



Fig. 131. 



General view of the external, middle, and internal ear, as seen in a prepared section through 

 a, the auditory canal. 6. The tympanum or middle ear. c. Eustachian tube, leading to the 

 pharynx, d. Cochlea; and e. Semicircular canals and vestibule, seen on their exterior, as 

 brought into view by dissecting away the surrounding petrous bone. The styloid process pro- 

 jects below ; and the inner surface of the carotid canal is seen above the Eustachian tube. 

 From Scarpa. 



The External Ear comprises the free, expanded part, auricle or 

 pinna, and the auditory canal or external meatus. 



The auricle presents an outer surface, which is on the whole con- 

 cave, and slightly inclined forwards. On this surface are several 

 eminences and depressions, resulting from the folded, or rather 

 crumpled, form of its cartilaginous basis, and which are seen re- 

 versed on the free portion of the opposite surface. These are ; 

 a prominent rim or helix, and within it another curved prominence, 

 the anthelix, which bifurcates above, so as to enclose a space, the 

 scaphoid fossa, and describes a circuit round a deep, capacious 

 central cup, the concha. At the end of the helix, in front of the 

 concha, is a small detached eminence, the tragus, so named from its 

 bearing a tuft of hair resembling a goat's beard. Opposite this, be- 

 hind and below the concha, is the antitragus. Below is the pen- 

 dulous lobe, composed of dense areolar and adipose tissues. The 

 concha is imperfectly divided into an upper and a lower part by the 



