THE EAR. 



Fig. 440. 



627 



Fig. 440: — Diagrammatic View from before op the Parts composing the Organ 

 OF Hearing op the Left Side (after Arnold). 



The temporal bone of the left side, with the accompanying soft parts, has been detached 

 from the head, and a section has been carried through it transversely so as to remove the 

 front of the meatus externus.half the tympanic membrane, and the upper and anterior wall 

 of the tympanum and Eustachian tube. The meatus internus has also been opened, and 

 the bony labyrinth exposed by the removal of the surrounding parts of the petrous bone. 

 1, the pinna and lobe ; 2 to 2', meatus externus ; 2', membrana tympani ; 3, cavity of the 

 tympaaum ; 3', its opening backwards into the mastoid cells ; between 3 and 3', the chain 

 of small bones ; 4, Eustachian tube ; 5, meatus internus containing the facial (upper- 

 most) and the auditory nerves ; 6, placed on the vestibule of the labyrinth above the 

 fenestra ovalis ; a, apex of the petrous bone ; b, internal carotid artery ; c, styloid pro- 

 cess ; d, facial nerve issuing from the stylo-mastoid foramen ; e, mastoid process ; /", 

 squamous part of the bone covered by integument. 



Fig. 441. — OnTER Surface of the Pinna of the Right Fig. 441. 



Auricle. | 



1, helix ; 2, fossa of the helix ; 3, antihelix ; 4, fossa of 

 the antihelix ; 5, antitragus ; 6, tragus ; 7, concha ; 8, 

 lobule. 



concha, and projecting backwards over the 

 meatus auditorius, is a conical prominence, the 

 tragus (fig. 441, 6), covered usually with hairs. 

 Behind this, and separated from it by a deep 

 notch (incisura intertragica), is another smaller 

 elevation, the antitragus (5). Beneath the 

 antitragus, and forming the lower end of the 

 auricle, is the loiule (8), which is devoid of the 

 firmness and elasticity that characterise the 

 rest of the pinna. The thinner and larger por- 

 tion of the pinna is bounded by a prominent 

 and incurved margin, the hdix (l), which, 

 springing above and rather within the tragus, from the hollow of the 



