An introduction to the diseases of infancy / by J.W. Ballantyne.

  • Ballantyne, J. W. (John William), 1861-1923.
Date:
1891
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to the diseases of infancy / by J.W. Ballantyne. Source: Wellcome Collection.

    67/292 (page 39)
    involving the membranes of the brain. Clinical evidence shows that this complication of ear di.seasc is very common m the nifant, and that tbereforo the prognosis in otitis media occurring in ear y life is graver; but at the same time it must be remembered that the thinness of the mastoid portion of the bone will render the opera- tion of trephining comparatively easy at this age^ and at this spot. If pus form here, and if the diagnosis be made with any degree of certainty, trephining the mastoid is indicated. The Mastoid Antrum.—The mastoid cells are not developed till after puberty; but, as Symington has shown, there exists in that part of the periotic hone which is named the pars mastoidca a large space, the antrum, which communicates with the tympanic cavity. In all the infants that were examined I found this mastoid antrum, and noted that it had, like the tympanic cavity, a very thin roof. which formed the only separation between it and the cerebral mem- branes. As the infant grows older, the walls, and especially the roof of the antrum, get thicker, and about the time of puberty become hollowed out into air-cells which communicate with each other and with the cavity of the antrum. No reference is made to the presence of the mastoid antrum in the ear of infants in the ordinary anatomical text-books. The Eustachian Tube.—The Imstachian tube is short in the infant. In one of my cases it measured 18 mms. in length, and Symington in two nine months’ foetu.ses found that its length was 17 and 18 mms. respectively. In the adult it measures from 35 to 36 mms., or twice its infantile length. Its direction is different in the infant from what it is in adult life, for in the former it runs almost horizontally. In one case it was traced throughout its whole course, and was found to run backwards with a .slight inclination outwards and downwards, forming an angle of about 10° with the horizon. The osseous part of the Eustachian tube can scarcely be said to be present at all in the infant, although in the adult it forms one-third of the tube. The cartilage of the tube is peculiar in form, being deficient inferiorly and externally. The pharyngeal end of the tube is small in infants, and lies in the same plane as the inferior meatus of the nose. Its aperture is peculiar, there being a prominent margin above and internally, which is wanting below and externally; and this peculiarity makes the passage of the Eustachian catheter less difficult than it would otherwise be. At its tympanic end it is difficult to .say where