. Quain's elements of anatomy . Fig. 891. Fig. 391.—Membranous labyrinth and NERVOUS TWIGS DETACHED, MAGNIFIED (Breschet). 7i, facial nerve in the meatus auditoriusiuLernus ; I, anterior division of the audi-tory nerve giving branches, o, m, n, to theutricle and the ampuUse of the superiorand external canals ; I, vestibular divisionof the auditory nerve, giving a branch, q, tothe saccule, another to the posterior am-pulla, q, and a third (?•) to the cochlea, r ;a, b, c, ampulla of the superior, external,and posterior semicircular canals respec-tively ; d, the united part of the superiorand pos
. Quain's elements of anatomy . Fig. 891. Fig. 391.—Membranous labyrinth and NERVOUS TWIGS DETACHED, MAGNIFIED (Breschet). 7i, facial nerve in the meatus auditoriusiuLernus ; I, anterior division of the audi-tory nerve giving branches, o, m, n, to theutricle and the ampuUse of the superiorand external canals ; I, vestibular divisionof the auditory nerve, giving a branch, q, tothe saccule, another to the posterior am-pulla, q, and a third (?•) to the cochlea, r ;a, b, c, ampulla of the superior, external,and posterior semicircular canals respec-tively ; d, the united part of the superiorand posterior canals ; e, the macula of theutricle ; /, the saccule. vestibule, close to the opening fromthe scala vestibuli of the cochlea, andis received into the hollow of thefovea hemispherica, from the bottomof which many branches of nerve enter it, and here there is a similarmacula in its wall. It also contains a small mass of THE MEMBEANOUS LABYRINTH. 451 The saccule is connected with the membranous canal of the cochleaby means of a short narrow canal, the canalis reuniens of Hensen {c. r.).There is also a minute canal, lined with epithelium, which passes fromthe utricle along the aqueductus vestibuli to end iDlindly in a dilatedextremity (saccus endo-lymphaticus {)) on the posterior surface of thepetrous bone just below the orifice of the aqueduct and lying in thetissue of the dura mater. This canal is joined near its origin by a smalltube from the saccule, so that in this way the cavity of the saccule isbrought into communication with that of the utricle (Boettcher). Semicircular Canals.—The membranous semicircular canalsare from one-third to one-fifth the diameter of the osseous tubes in whichthey are lodged, and are dilated into ampuUse within the ampullary en-largements of those tubes. In section they are oval or somewhat elliptical(fig. 392). At the ampuUse they are thicker and less translucent
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