1136 SPLANCHNOLOGY 



branches from the deep surface of the gland, and runs forward between the Mylo- 

 hyoideus 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 linguse. 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 t 

 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 linguse, 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 Rimnus}, some join the sub- 

 maxillary 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 linguse. One or more join to form the larger sublingual 

 duct (duct of Bartholiri), 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 mem- 

 brana 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. 





