ORGANS OF DIGESTION 



143 



THE ACCESSORY GLANDS OF DIGESTION 



• The salivary glands are five in number on each side of the 

 head. They secrete the saliva, of which certain elements have 

 the power of changing starch into sugar. 



The parotid gland is the largest of the sahvary group and 

 lies just ventrad to the base of the external ear (Fig. 72) 

 beneath the skin. It is flat and about two centimeters in 

 diameter. Its secretion is poured into the mouth through the 

 parotid duct, (ductus parotideus stenonis), which may be seen 

 extending from the cranial mar- 

 gin of the gland over the masseter 

 muscle, to near the angle of the 

 mouth, where it perforates the 

 buccinator muscle, and opens 

 within the mouth on the cheek, 

 opposite the prominent cusp of 

 the last premolar. The duct 

 and gland may be injected 

 with Berlin blue by inserting 

 the cannula into the orifice of 

 the duct (Fig. 72). 



The submaxillary gland is 

 near the angle of the mandible 

 and ventrad to the parotid. The submaxillary duct extends 

 from its anterior surface, between the digastric and masseter 

 muscles, to its orifice on the floor of the mouth, opposite the 

 last tooth of the mandible. 



The sublingual gland is quite small, elongated, and lies 

 craniad of the submaxillary. Its duct extends parallel with 

 that of the submaxillary and opens within the mouth upon 

 the same papilla beneath the tongue. The molar gland is very 

 small and lies near the angle of the mouth ventrad of the pa- 

 rotid. Its several ducts, which are not easily demonstrated, 

 pass through the cheek to open within the mouth. The zygo- 

 matic or infraorbital gland lies on the lateral part of the orbit 



Fig. 72. — Lateral Aspect of the 

 Head with the Skin Removed. 

 cr. Carotid artery; es, esophagus; 

 Im, lymphatic gland; nr, vagus and 

 sympathetic nerves; 5?w, submaxillary 

 gland; tr, trachea; v, cervical vertebra. 



