. Animal and vegetable physiology, considered with reference to natural theology. Biology; Physiology; Plant physiology; Natural theology. HEARING. 301 these evils by establishing a passage of communication be- tween the tympanum and the external air, by means of a tube (e,) termed the Eustachian tube, which begins by a small orifice from the inner side of the cavity of the tympa- num, and opens by a wide mouth at the back of the nos- trils.* This tube performs the same office in the ear, as the hole which it is found necessary to make in the side of a drum, for the purpose of opening a commun
. Animal and vegetable physiology, considered with reference to natural theology. Biology; Physiology; Plant physiology; Natural theology. HEARING. 301 these evils by establishing a passage of communication be- tween the tympanum and the external air, by means of a tube (e,) termed the Eustachian tube, which begins by a small orifice from the inner side of the cavity of the tympa- num, and opens by a wide mouth at the back of the nos- trils.* This tube performs the same office in the ear, as the hole which it is found necessary to make in the side of a drum, for the purpose of opening a communication with the external air; a communication which is as necessary for the functions of the ear, as it is for the proper sounding of the drum. We find accordingly that a degree of deafness is induced whenever the Eustachian tube is obstructed, which may happen either from the swelling of the membrane lining it, during a cold, or from the accumulation of secre- tion in the passage. It is also occasionally useful as a chan- nel through which sounds may gain admittance to the inter- nal ear; and it is perhaps for this reason that we instinct- ively open the mouth when we are intent on hearing a very faint or distant sound. On the side of the cavity of the tympanum, which is op- posite to the opening of the Eustachian tube, is situated the beginning of another passage, leading into numerous cells, contained in the mastoid process of the temporal bone, and therefore termed the mastoid cells: these cells are likewise. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Roget, Peter Mark, 1779-1869. Philadelphia, Carey, Lea & Blanchard
Size: 2281px × 1095px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury18, booksubjectnaturaltheology, booksubjectphysiology
