A text-book of the diseases of the ear and adjacent organs . o the cupola, and there ends in the pointed hamu-lus. It serves for the insertion of the membranous spiral lamina, which willbe described later. By it the cochlear canal is divided into two divisions, thesuperior of which (scala vestibuli) communicates with the vestibule, while the THE INTERNAL AUDITORY MEATUS. 589 inferior (scala tympani) ends at the fenestra rotunda closed by the secund. The scalar communicate with each other at the apex of thecochlea through the helicotrema of Breschetius. All the spaces of the labyr
A text-book of the diseases of the ear and adjacent organs . o the cupola, and there ends in the pointed hamu-lus. It serves for the insertion of the membranous spiral lamina, which willbe described later. By it the cochlear canal is divided into two divisions, thesuperior of which (scala vestibuli) communicates with the vestibule, while the THE INTERNAL AUDITORY MEATUS. 589 inferior (scala tympani) ends at the fenestra rotunda closed by the secund. The scalar communicate with each other at the apex of thecochlea through the helicotrema of Breschetius. All the spaces of the labyrinth are lined by a layer of connective tissueintermixed with fine elastic fibres. d. The Internal Auditory Meatus varies in regard to its length and course from the oval opening on the posterior surface of the pyramid isdirected outwards and backwards (Fig. 291, e). The inner end is dividedinto a superior and an inferior fossa by a diagonal ledge. In the anterior partof the superior depression is situated the entrance to the Fallopian canal, and. Fig. 298.—The Membranous Internal Ear of a Human Embryo, 5 Months 10 times (from behind and within). (After Retzius.) up, Utric. propr. ; re, Recessus utriculi; S, Sacculi; ss, Sinus utric. superior. ; sp,Sinus utric. post. ; cH, Canalis reuniens Henseni ; a, Ampulla anterior. ; ap, Am-pulla posterior. ; ca, Canalis semicir. ant ; ce, Canalis semicir. externus; de,Ductus endoymphaticus ; ra, Ramulus vestib. ; /, Ntrvus facialis ; np, Ramulusampullae posterioris. in the posterior part the opening of the passage for the vestibular nerves. Inthe inferior fossa (fossa cochleae, Fig. 296) are seen the spirally arrangedorifices (tractus spiralis foraminulentus) at the base of the cochlea for theentrance of the fibres of the cochlear nerve. Besides, there are, on the pos-terior wall of the meatus internus, a small group of openings for the passageof a few branches of the ramus vestibuli. 2. The Membranous Labyrinth.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjecteardiseases, bookyear
