A text-book of the diseases of the ear and adjacent organs (1894) (14758740436)

Identifier: adjacendis00poli (find matches)
Title: A text-book of the diseases of the ear and adjacent organs
Year: 1894 (1890s)
Authors: Politzer, Adam, 1835-1920 Dodd, Oscar Dalby, William B. (William Bartlett), Sir, 1840-1918
Subjects: Ear Diseases
Publisher: Philadelphia : Lea Brothers & Co.
Contributing Library: Yale University, Cushing/Whitney Medical Library
Digitizing Sponsor: Open Knowledge Commons and Yale University, Cushing/Whitney Medical Library



Text Appearing Before Image:
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 rnembr.tynip. 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 width.Its 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
Text Appearing After Image:
Fig. 298.—The Membranous Internal Ear of a Human Embryo, 5 Months old.Enlarged 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. The membranous labyrinth, lying in the osseous capsule just d