886 



THE ORGANS OF DIGESTION. 



detached portion of the gland, soda par otidis, which occasionally exists as a separate 

 lobe, just beneath the zygomatic arch. In this position it has the transverse facial 

 artery above it and some branches of the facial nerve below it. 



Structure. The parotid duct is dense, of considerable thickness, and its canal 

 about the size of a crowquill, but at its orifice on the inner aspect of the cheek its 

 lumen is greatly reduced in size ; it consists of an external or fibrous coat, of 

 considerable density, containing contractile fibres, and of an internal or mucous 

 coat lined with short columnar epithelium. 



Surface Form. The direction of the duct corresponds to a line drawn across the face 

 about a finger's breadth below the zygoma ; that is, from the lower margin of the concha to 

 midway between the free margin of the upper lip and the ala of the nose. 



Vessels and Nerves. The arteries supplying the parotid gland are derived from 

 the external carotid, and from the branches given off by that vessel in or near its 

 substance. The veins empty themselves into the external jugular through some 

 of its tributaries. The lymphatics terminate in the superficial and deep cervical 



Crescent of Gianuzsi. 



Salivary duct. 



FIG. 484. A highly magnified section of the snbmaxillary gland of the dog, stained with carmine. (Kolliker.) 



glands, passing in their course through two or three lymphatic glands placed on 

 the surface and in the substance of the parotid. The nerves are derived from the 

 plexus of the sympathetic on the external carotid artery, the facial, the auriculo- 

 temporal, and great auricular nerves. 



It is probable that the branch from the auriculo-temporal nerve is derived 

 from the glosso-pharyngeal through the otic ganglion (which see). At all events, 

 in some of the lower animals this has been proved experimentally to be the 

 case. 



The submaxillary gland is situated below the jaw, in the anterior part of the 

 submaxillary triangle of the neck. It is irregular in form and weighs about two 

 drachms (8-10 grammes). It is covered by the integument, Platysma, deep cer- 

 vical fascia, and the body of the lower jaw, corresponding to a depression on the 

 inner surface of the bone, and lies upon the Mylo-hyoid, Hyo-glossus, and Stylo- 

 glossus muscles, a portion of the gland passing beneath the posterior border of 

 the Mylo-hyoid. In front of it is the anterior belly of the Digastric ; behind, it 

 is separated from the parotid gland by the stylo-maxillary ligament, and from the 

 sublingual gland in front by the Mylo-hyoid" muscle. The facial artery lies im- 

 bedded in a groove in its posterior and upper border. 



The duct of the submaxillary gland ( Whartoris) is about two inches in length, 

 and its walls are much thinner than those of the parotid duct. It commences by 

 numerous branches from the deep portion of the gland which lies on the upper 

 surface of the Mylo-hyoid muscle, and passes forward and inward between the 

 Mylo-hyoid and the Hyo-glossus and Genio-hyo-glossus muscles, then between the 

 sublingual gland and the Genio-hyo-glossus, and opens by a narrow orifice on the 



