A text-book of the diseases of the ear / by Josef Gruber.

  • Gruber, Josef, 1827-1900.
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of the diseases of the ear / by Josef Gruber. Source: Wellcome Collection.

    48/618 (page 14)
    Fig. 9. Temporal bone of an infant seen from the outer side. fg s, Squama ; fins, fins', fissura mastoideo- squamosa ; fg, fissura Glaseri; fsm, foramen stylo-mastoideum. I. Connection of the sqitamo-zygomatic with the petro-mastoid portion (Figs. 9 and 10).—Both lamellae of the horizontal part of the squamous portion join the petro-mastoid. The internal lamella abuts with its free edge against the outer margin of the tegmen tympani, a small amount of soft connective tissue completing the union. This loose connection has the appearance of a fissure, which is called the fissura petro-squamosa s. sulcus pctro-squamosa (Fig. io, sp). While the anterior part of the internal lamella touches the cor- responding part of the tegmen tympani, which forms the roof of the tympanic cavity, its poste- rior part articulates with the free margin of the posterior part of the tegmen, and assists in the for- mation of the sulcus mastoideus. The outer lamella of the horizontal portion of the squama articulates only by its posterior part with the petro-mastoid, and thus the angular space between its two lamellae comes into con- sideration, since its anterior part, bounded, as we have already seen, by smooth walls, serves for the enlargement of the roof of the tympanum; while its pos- terior part, limited by rougher walls, serves for the completion of the sulcus mastoideus. The posterior part of this outer lamella projects downwards to the mastoid portion near to the foramen stylo-mastoideum. The connection between the hori- zontal part of the squama and the mastoid portion is indicated by the fissura mastoideo-squaniosa, which is of extreme importance in practice (Fig. 9, finis). That part, slightly undulating below, between the two processes of the outer lamella of the Temporal bone of an infant side. s, Inner surface of the squama; sp, fissura petro- squamosa; z, processus zygomaticus; lief, hiatus canal. Fallopii; sp, apex of petrous portion; in, entrance to internal auditory canal ; a, termination of aquasd. vestib. ; b, depression below the superior semicircular canal; fsm, foramen stylo-mastoideum ; ss, sulcus sig- moideus, on the inner surface of the mastoid portion.