CH. LVL] 



ANATOMY OF THE EAR 



789 



FIG. 486. Diagrammatic view from before of the parts composing the organ of hearing of the left side. 

 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, 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, meatus 

 externus ; 2', membrana tympani ; 3, cavity of the tympanum ; 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 (uppermost) and the auditory nerves ; 6, placed on the vestibule of the laby- 

 rinth above the fenestra ovalis ; a, apex of the petrous bone ; b, internal carotid artery : c, styloid 

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

 part of the bone covered by integument, etc. (Arnold.) 



Fio. 487. The hammer- 

 bone or malleus, seen 

 from the front. 1, The 

 head ; 2, neck ; 3, 

 short process ; 4, 

 handle. (Schwalbe.) 



Fio. 488. The incus, or anvil-bone. 

 1, Body; 2, ridged articulation 

 for the malleus; 4, processus 

 brevis, with 5, rough articular 

 surface for ligament of incus ; 

 6, processus magnus, with articu- 

 lating surface for stapes; 7, nu- 

 trient foramen. (Schwalbe.) 



Fio. 489. The stapes, or 

 stirrup - bone. 1, Base; 

 2 and 3, arch; 4, head 

 of bone, which articu- 

 lates with orbicular 

 process of the incus ; 

 5, constricted part of 

 neck; 6, one of the 

 crura. (Schwalbe.) 



