Henry Gray (18251861). Anatomy of the Human Body. 1918.
branches from the deep surface of the gland, and runs forward between the Mylohyoideus and the Hyoglossus and Genioglossus, then between the sublingual gland and the Genioglossus, and opens by a narrow orifice on the summit of a small papilla, at the side of the frenulum linguæ. On the Hyoglossus it lies between the lingual and hypoglossal nerves, but at the anterior border of the muscle it is crossed laterally by the lingual nerve; the terminal branches of the lingual nerve ascend on its medial side.
Vessels and Nerves.The arteries supplying the submaxillary gland are branches of the external maxillary and lingual. Its veins follow the course of the arteries. The nerves are derived from the submaxillary ganglion, through which it receives filaments from the chorda tympani of the facial nerve and the lingual branch of the mandibular, sometimes from the mylohyoid branch of the inferior alveolar, and from the sympathetic.
Sublingual Gland (glandula sublingualis).The sublingual gland (Fig. 1024) is the smallest of the three glands. It is situated beneath the mucous membrane of the floor of the mouth, at the side of the frenulum linguæ, in contact with the sublingual depression on the inner surface of the mandible, close to the symphysis. It is narrow, flattened, shaped somewhat like an almond, and weighs nearly 2 gm. It is in relation, above, with the mucous membrane; below, with the Mylohyoideus; behind, with the deep part of the submaxillary gland; laterally, with the mandible; and medially, with the Genioglossus, from which it is separated by the lingual nerve and the submaxillary duct. Its excretory ducts are from eight to twenty in number. Of the smaller sublingual ducts (ducts of Rivinus), some join the submaxillary duct; others open separately into the mouth, on the elevated crest of mucous membrane (plica sublingualis), caused by the projection of the gland, on either side of the frenulum linguæ. One or more join to form the larger sublingual duct (duct of Bartholin), which opens into the submaxillary duct.
Vessels and Nerves.The sublingual gland is supplied with blood from the sublingual and submental arteries. Its nerves are derived from the lingual, the chorda tympani, and the sympathetic.
Structure of the Salivary Glands.The salivary glands are compound racemose glands, consisting of numerous lobes, which are made up of smaller lobules, connected together by dense areolar tissue, vessels, and ducts. Each lobule consists of the ramifications of a single duct, the branches ending in dilated ends or alveoli on which the capillaries are distributed. The alveoli are enclosed by a basement membrane, which is continuous with the membrana propria of the duct and consists of a net-work of branched and flattened nucleated cells.
The alveoli of the salivary glands are of two kinds, which differ in the appearance of their secreting cells, in their size, and in the nature of their secretion. (1) The mucous variety secretes a viscid fluid, which contains mucin; (2) the serous variety secretes a thinner and more watery fluid. The sublingual gland consists of mucous, the parotid of serous alveoli. The submaxillary contains both mucous and serous alveoli, the latter, however, preponderating.
The cells in the mucous alveoli are columnar in shape. In the fresh condition they contain large granules of mucinogen. In hardened preparations a delicate protoplasmic net-work is seen, and the cells are clear and transparent. The nucleus is usually situated near the basement membrane, and is flattened.
In some alveoli are seen peculiar crescentic bodies, lying between the cells and the membrana propria. They are termed the crescents of Gianuzzi, or the demilunes of Heidenhain(Fig. 1025), and are composed of polyhedral granular cells, which Heidenhain regards as young epithelial cells destined to supply the place of those salivary cells which have undergone disintegration. This view, however, is not accepted by Klein. Fine canaliculi pass between the mucus-secreting cells to reach the demilunes and even penetrate the cells forming these structures.
In the serous alveoli the cells almost completely fill the cavity, so that there is hardly any lumen perceptible; they contain secretory granules imbedded in a closely reticulated protoplasm (Fig. 1026). The cells are more cubical than those of the mucous type; the nucleus of each is spherical and placed near the center of the cell, and the granules are smaller.
Both mucous and serous cells vary in appearance according to whether the gland is in a resting condition or has been recently active. In the former case the cells are large and contain many secretory granules; in the latter case they are shrunken and contain few granules, chiefly collected at the inner ends of the cells. The granules are best seen in fresh preparations.