Rudiments of animal physiology : for use in schools, and for private instruction / by G. Hamilton.

  • Hamilton, George, 1808-1885
Date:
1839
Catalogue details

Licence: Public Domain Mark

Credit: Rudiments of animal physiology : for use in schools, and for private instruction / by G. Hamilton. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    a shut cavit}^, bounded by the closed lips anteriorly, the cheeks laterally, and the root of the tongue and the curtain of the palate brought together posteriorly. In Fig. 11, which represents the throat or pha- rynx cut open behind, d is the curtain {velum palati), Avith its central dependent part called the uvula, and c, the tongue. When the food has been properly moistened, and broken down, it is rolled into the form of a ball, and is passed backwards by the tongue and other muscles into the pharynx, which may be conceived of as a kind of bag, having the nostrils {aa) open- ing into it from above; the mouth (6) opening below these ; the glottis (e), and the gullet, ot oesophagus (i), still lower ; besides two other openings, called Eustachian tubes, which open on its sides, Fie:. ]L Back of the Pharynx cut open.* and lead to the internal ear. 28. Before the food can get into the pharynx, the curtain (c?), which we have said is, during mastication, applied closely to the root of the tongue, must be lifted up. But if nothing more were done, the food or drink might pass from the pharynx into any or all of the openings mentioned, the inconvenience attend- ing which, every one has experienced when a morsel of food or a little fluid gets into the nostrils or the windpipe. This, however, is effectually prevented, for the curtain is not only lifted up, but is also instantly applied closely to the back of the pharynx, so as to cut off the communication with the nostrils, and close the Eustachian openings ; while, at the same instant, the sides of the glottis, or opening into the windpipe (e), are drawn toge- ther, and a gristly substance, the epiglottis {g), is folded back over it. The food, being still forced backwards, passes rapidly over the epiglottis into the gullet (i), the only opening it can * a a., the nostrils, h, the mouth, c, the tongue, d, the curtain of the soft palate, e, the glottis, opening into the windpipe, g, the epiglottis, i, the gullet, k, the windpipe.
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