A manual of diseases of the ear, for the use of students and practitioners of medicine / by Albert H. Buck.

  • Buck, Albert H. (Albert Henry), 1842-1922.
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: A manual of diseases of the ear, for the use of students and practitioners of medicine / by Albert H. Buck. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    tein at least, if not during life) the small six-sided crystals of car- bonate of lime known as otoliths.1 There still remains to be considered the cochlea, the most com- plicated and evidently the most essential part of the labyrinth. The auditory nerve, it will be remembered, gains entrance into the cochlea by way of the modiolus—the cone-shaped standard of bone around which the cochleal channels are coiled spirally. The base of this standard corresponds with the cribriform bot- tom, or cul de sac, of the porus acusticus internus; its summit, with the cupola or highest point of the scala vestibuli. The modiolus is traversed lengthwise by countless channels through Fig. 114.--Transverse Section of the Human Cochlea in the Plane of the Axis of the Modiolus. (After Breschet.) x circa 12 diameters, a. a, a. Trunk of the cochlear portion of the auditory nerve: b. b, filaments of this nerve branching off from the trunk and passing into the substance of the lamina spiralis ossea: c, c, anastomosing nerve filaments; d, d, lamina spiralis membranacea; e, e. ligamentum spirale of Henle; 1,1,1, osseous modiolus; 2, columella; 3, 3, outer bony shell of the cochlea; 4. 4, partition of bone separating the individual cochleal whorls: 5.5, tympanic ?>ortion of the lamina spiralis ossea: 6, 6, vestibular portion of the same; 7. hamu- us; 8, helicotrema. A black bristle is represented as passing from the scala tympani below, through the helicotrema, into the scala vestibuli above. which run the filaments of the auditory nerve. From the base to the vicinity of the summit of this conical core of the cochlea, nerve filaments are constantly being given off laterally to the spiral diaphragm which separates the two scalre from each other. Just as the filaments arc about to leave the modiolus and enter the substance of the lamina spiralis—the technical name of the diaphragm just mentioned,—they pass through an aggregation of ganglion nerve cells (ganglion spirale, Fig. 115). Up to this point, and even beyond it, as far as to the line of junction between the lamina Bpiralis ossea and the lamina spiralis membrancea, the nerve filaments retain their sheathing (white substance of ■ These anatomical relations have been t lmnmghly investigated by Urban Pritch- ard (Quarterly Journal for Medical Science, 1876.)