Anatomy and physiology : designed for academies and families . al, and what is theiruse ? Where are the ceruminous follicles ? What does Fig. 194 repre-sent ? Describe the membrana tympani, or drum of the ear. Of howmany layers is the drum of the ear composed ? Describe the tympanum. 284 ANATOMY AND PHYSIOLOGY. It is bounded externally by the membrana tympani; inter-nally by its inner wall; and in its circumference by the pe-trous bone and mastoid cells. The tympanum contains four small bones, ossicula audita,named separately, the malleus, incus, stapes, and orbicular. Fig. 195. 0= Fig. 195. R
Anatomy and physiology : designed for academies and families . al, and what is theiruse ? Where are the ceruminous follicles ? What does Fig. 194 repre-sent ? Describe the membrana tympani, or drum of the ear. Of howmany layers is the drum of the ear composed ? Describe the tympanum. 284 ANATOMY AND PHYSIOLOGY. It is bounded externally by the membrana tympani; inter-nally by its inner wall; and in its circumference by the pe-trous bone and mastoid cells. The tympanum contains four small bones, ossicula audita,named separately, the malleus, incus, stapes, and orbicular. Fig. 195. 0= Fig. 195. Represents the four bones of the ear. The smallest is represented This bone is earlv matured, and in the adult it becomes united with the in-cus. These bones are retained in their places and moved by three ligaments and fourmuscles. There are ten openings into the tympanum or middle ear;five large and five small openings. The larger openings arethe Meatus auditorius, Fenestra ovalis, Fenestra rotunda, Mas-toid cells, and Eustachian tube. Fig. Fig. 196. Represents the pinna, meatus, membrana tympani, ossicula andita, andsemicircular canals, a, The pinna, c, The meatus auditorius. g. The membranatympani. £, The tympanum, e. The ossicula audita. 6, the semicircular canals. /,The cochlea. A, The vestibule, t, The Eustachian tube, d, the auditory nerve,the student describe the external and middle ear from this engraving. lit How many bones are contained in the tympanum ? What is said of theorbicular, or smallest bone of the ear ? fiow many openings into the mid-dle ear ? Name them. Describe Fig. 196. ANATOMY OF THE ORGANS OP HEARING. 285 The Fenestra ovalis is the opening of communication be-tween the tympanum and the vestibule. It is closed by thefoot of the stapes, and by the lining membrane of both cav-ities. The Fenestra rotunda serves to establish a communica-tion between the tympanum and the cochlea. It is closedby a proper membrane, as well as by the lining
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectanatomy, bookyear1847
