xii CONTENTS. 



CHAPTER IV. 

 HEARING. 



SECTION I. 



ON THE GENERAL STRUCTURE OF THE EAR AND ON THE STRUCTURE 

 AND FUNCTIONS OF THE SUBSIDIARY AUDITORY APPARATUS. 



PAGE 



808. The Embryonic History of the Ear. The Otic Vesicle .... 176 

 809. The General Relations of the Parts of the Ear; Vestibule and 

 Cochlea, Membranous and Bony Labyrinth, Tympanum, Audi- 

 tory Ossicles, Membrana Tympani, and External Meatus . . 177 

 810. The General Use of the Several Parts ......... 180 



The Conducting Apparatus of the Tympanum. 



811. The Auditory Ossicles ..... ..... ..... 181 



812. The Tympanum ; its Structure and Relations ....... 182 



813. The Membrana Tympani .............. 185 



814. The Joints, Ligaments, and Positions of the Auditory Ossicles . 187 



815. The Chain of Ossicles as a Lever ........... 189 



The Conduction of Sound through the Tympanum. 



816, Longitudinal and Transversal Sonorous Vibrations. The Vibra- 



tions of the Tympanic Membrane .......... 190 



817. The Conduction of Vibrations through the Chain of Ossicles . . 192 



818. The Conduction of Vibrations through the Bones of the Skull . . 193 



819. The Action of the Tensor Tympani and Stapedius Muscles ... 194 



820. The Eustachian Tube ............... 196 



SECTION II. 

 THE STRUCTURE OF THE LABYRINTH. 



821 . The Parts of the Vestibule ; Utricle, Saccule, and Semicircular Canals 198 



822. The Perilymph Cavity of the Vestibule ......... 200 



823. The Auditory Nerve ; the Maculae and Cristse Acusticse .... 201 



824. The General' Structure of the Cochlea ......... 202 



The refttibular Labyrinth. 



825. The Minute Structure of the Parts free from Nerve Endings . , 206 



826. The Structure of the Crista Acusticse ... ... 206 



