A text-book on diseases of the ear, nose and throat . septum from the modiolus to theopposite wall of the canal, the separation of the two scalse from eachother is not complete until the soft parts are added to the osseous struc-tures (Fig. 50, 6). The lamina spiralis is thicker at its lower end thanat the top of the modiolus. At the former point it may amount to three-tenths of a millimetre, but at the upper part to only fifteen-hundredths ofa millimetre. The width of the lamina spiralis is one and two-tenths milli-metres at the lowest part and five-tenths of a millimetre at the upper part. T
A text-book on diseases of the ear, nose and throat . septum from the modiolus to theopposite wall of the canal, the separation of the two scalse from eachother is not complete until the soft parts are added to the osseous struc-tures (Fig. 50, 6). The lamina spiralis is thicker at its lower end thanat the top of the modiolus. At the former point it may amount to three-tenths of a millimetre, but at the upper part to only fifteen-hundredths ofa millimetre. The width of the lamina spiralis is one and two-tenths milli-metres at the lowest part and five-tenths of a millimetre at the upper part. The Semicircular Canals.—To the posterior part of the vestibule areattached the three semicircular canals. These are named, accoiding totheir positions and planes, the superior, the posterior, and the horizontalsemicircular canal (Fig. 48). Although there are three distinct canals, there are but five openingsfrom them into the vestibule. This is due to the fact that two of thecanals, the superior and the posterior, are joined to a common shaft just. c3 = 3 C >.!3 cS O _ ^ o c ^ ^ = ?5 s ;: i 53 g ^ - lu^ t^ i « - ? O Ilia? -2-* r^ c 2>^ t — 3 o E^ e > 4i ^ c^ & ?p. a) p>- c ^__ 3 > M g u > 3 cc c 1 1 S 11 O1 s od 1 o8i ^ a> O ^.2 Td © c 1 > 43 a> B » be ^g % .* o •c >i a> > r; A m^ 1 ?E CJ A 1 S> .4-3 OJ Si 1 j:: fi.^^ o3 53 0) o o >. 1^ s ?q i a;o 1 C3 g o ^ o ^.5 n: C p. rH r-J o- 3 s S5 i 1 aj „- SbcS ^ t ANATOMY AND PHYSIOLOGY OF THE INTERNAL EAR. 63 before they reach the vestibule (Fig. 48, d^ and Plate I., 17, 21, and 22).The position of these ox^eiiings on the wall of the vestibule has been de-scribed already. At one end, each of the canals has a dilated portion, itsampullar enlargement. These enlargements contain soft parts of similarname and shape, the ampullse of the membranous semicircular canals(Plate I., 15, 18, and 24). Dimensions of the Semicircular Ccuuds.—The length of the posteriorsemicircular canal is the
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