HANDBOOK OF ACOUSTICS - online book

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23
CHAPTER III.
On the Ear.
The Human Ear is separable into three distinct parts—the External, the Middle, and the Internal.
The External ear consists of the cartilaginous lobe or Auricle, and the External Meatus (E. M. fig. 16). The latter is a tube about an inch and a quarter long, directed inwards and slightly forwards, and closed at its inner extremity by the Tympanum (Ty., fig. 16) or drum of the ear, which is stretched obliquely across it.
Fig 16. Diagrammatic Section of the Human Ear.
The Middle ear, which is separated from the External by the Tympanum, is a cavity in the bony wall of the skull, called the Tympanic Cavity (Ty. C, fig. 16). From this, a tube, about an inch and a half long, termed the Eustachian Tube (Eu., fig. 16) leads to the upper part of the throat, and thus places the air in the Tympanic Cavity in communication with the external air. On the side opposite to the tympanum, there are two small apertures in the bony wall of the cavity, both of which, however, are closed with