. Kirkes' handbook of physiology . ternal pterygoids acl together, the lower jaw is pulleddirectly forward, so that the lower incisor teeth are brought in front of the levelof the upper. The act of mastication is voluntary. It will suffice here to state that theafferent nerves chiefly concerned are the sensory branches of the fifth andtenth or glossopharyngeal, and the efferent are the motor branches of thefifth and the twelfth, or hypoglossal, cerebral nerves. The act of mastication is much assisted by the saliva, which is secreted bythe salivary glands in largely increased amount during the
. Kirkes' handbook of physiology . ternal pterygoids acl together, the lower jaw is pulleddirectly forward, so that the lower incisor teeth are brought in front of the levelof the upper. The act of mastication is voluntary. It will suffice here to state that theafferent nerves chiefly concerned are the sensory branches of the fifth andtenth or glossopharyngeal, and the efferent are the motor branches of thefifth and the twelfth, or hypoglossal, cerebral nerves. The act of mastication is much assisted by the saliva, which is secreted bythe salivary glands in largely increased amount during the process. Theintimate incorporation of the saliva with the food is termed insalivation. The Salivary Glands. The glands which secrete the saliva inthe human subject are the salivary glands proper, the parotid, the submaxil-lary, and the sublingual, and numerous smaller bodies of similar structure,and with separate ducts, which are scattered thickly beneath the mucousmembrane of the lips, cheeks, soft palate, and root of the Fig. 248. Fig. 249. Fig. 248.—Section of the Submaxillary Gland of a Dog, Resting Stage. Most of the Alveolarcells are large and clear, being filled with the material for secretion (in this case, mucigen), whichobscures their protoplasm; some of the cells, however, are small and protoplasmic, forming thecrescents seen in most of the alveoli. (Ranvier.) Fig. 249.—Section of a Similar Gland after a Period of Activity. The mucigen has been dis-charged from the mucin-secreting cells, which consequently appear shrunken and less clear. Boththe cells and the alveoli are much smaller, and the protoplasm of the cells is more apparent. Thecrescents of Gianuzzi are enlarged, c. Crescent cells; g, mucus-secreting cells; /, lumen of alveolus.(Ranvier.) Histological Structure. The salivary glands are compound tubularor tubulo-racemose glands. They are made up of lobules. Each lobule con-sists of the branchings of a division of the main duct of the gland, which
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