. The physiology of the domestic animals; a text-book for veterinary and medical students and practitioners. Physiology, Comparative; Domestic animals. SENSE OF HEARING. 877 internal ear is formed of the vestibule, semicircular canals, and cochlea; the latter, being but little developed, is not convoluted in a spiral form, but, resembling that of lizards and serpents, consists of an almost straight osseous tube canal terminating in a cul-de-sac. In mammals the ear, for the convenience of study, may be divided into three parts—the external, the middle, and the internal ear. Of these three the i
. The physiology of the domestic animals; a text-book for veterinary and medical students and practitioners. Physiology, Comparative; Domestic animals. SENSE OF HEARING. 877 internal ear is formed of the vestibule, semicircular canals, and cochlea; the latter, being but little developed, is not convoluted in a spiral form, but, resembling that of lizards and serpents, consists of an almost straight osseous tube canal terminating in a cul-de-sac. In mammals the ear, for the convenience of study, may be divided into three parts—the external, the middle, and the internal ear. Of these three the internal ear is the essential, and the others are simply for the purpose of receiving or modifying impressions from the sounding bod}'. In the external ear we include the auricle, or pinna, and the external auditory meatus, bounded internally by the membrane of the tympanum ; in the middle ear, the tympanum, or drum of the ear, -with its contained ossicles; and in the internal ear, that portion situated in the petrous por- tion of the temporal bone, consisting of the semicircular canals, the vestibule, and the cochlea (Fig. 398).. Fig. 398.—Scheme of the Organ of Hearing. (Landois.) AG, external auditory meatus; T, tympanic membrane; K, malleus with its head (h), short process (Kf), and handle (m) : a, incus with its short process (x) and long process: the latter is united to the stapes (s) by means of the Sylvian ossicle (z); P. middle ear; o, fenestra ovalis; r, fenestra rotunda; x, beginning of the lamina spiralis of the cochlea; pt, its scala tympani; vt, its scala vestibuli; V, vestibule; S, saccule; U, utricle; H, semicircular canals; TE. Eustachian tube. The long arrow indicates the line of traction of the tensor tympani; the short, curved one, that of the stapedius. In different groups of mammals a marked difference is found in the form and size of the auricle, or pinna. This, in the majority of cases, is a trumpet-shaped dilatation of the external auditory canal for
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectphysiol, bookyear1890
