SALIVAEY GLANDS. 1137 



inwards through the fat of the cheek, practically at right angles to the first part 

 of its course, to reach the buccinator, which it pierces. Then passing for some 

 distance (5 to 10 mm.) between the buccinator and the mucous membrane, it 

 opens into the vestibule of the mouth by a very small orifice, on a variably 

 1 developed papilla, opposite the crown of the second upper molar tooth. 



The course of the duct, which is fairly constant, can be marked on the side of 

 the face by drawing a line from the inferior edge of the acoustic meatus to a point 

 midway between the ala of the nose and the red of the lip ; the middle third 

 of this line corresponds fairly accurately, on the surface, to the course pursued 

 by the duct. 



The duct measures from 1^ to 2^ inches (38 to 62 mm.) in length, and J inch (3 to 4 mm.) 

 in diameter. The calibre of the duct is very much greater than that of its orifice, which admits 

 only a fine bristle, and for this reason the duct may, to some extent, be looked upon as a 

 reservoir for the saliva, as well as a duct for its conveyance. In the child it pierces the " sucking' 

 pad " on its way to the mouth. 



A number of vessels and nerves are found in intimate relation to the parotid gland. 



These are : (1) The external carotid artery and its two terminal branches. This artery lies 

 at first in a groove in the inferior and deep aspect of the gland. It then enters the gland substance 

 and lies deeply in it, as far up as to the neck of the mandible, when it divides into its two terminal 

 branches. The superficial temporal artery passes onwards and emerges from the superior super- 

 ficial part of the gland, and th internal maxillary artery turns inwards and emerges from the 

 deep part of the anterior surface. 



The transverse facial artery is given off in the substance of the gland, and emerges from 

 it between the zygomatic arch and the duct. 



The posterior facial vein descends in the substance of the gland superficially, and divides in 

 it into the two terminal branches which emerge from the inferior part of the gland. 



The facial nerve enters the posterior surface of the gland, slightly below its middle, and runs 

 forwards and laterally, dividing into its main branches within the gland, and lying superficial 

 to the external carotid artery and posterior facial vein. Communicating branches from the 

 auriculo-temporal and great auricular nerves to the facial also traverse the gland substance. 



Vessels and Nerves. The arteries which supply the gland arise from the external carotid 

 artery, and from the branches of this artery in relation to the gland. 



The veins join the posterior facial vein and its tributaries. The lymph, vessels pass to both 

 the superficial and the deep cervical glands ; there are also a few small parotid lymph glands, 

 which lie on the surface of the superior and inferior part of the parotid beneath the capsule. 

 Some are said to be embedded in the substance of the parotid itself. 



The nerves are derived (a) from the auriculo-temporal, great auricular, and facial, and 

 (6) from the plexus caroticus externus. The fibres of the sympathetic are mainly vaso-constrictor. 



The secretory fibres to the gland, arising in the brain-stem, pass out through the glosso- 

 pharyngeal nerve, and pass from it through the lesser superficial petrosal nerve to the otic ganglion, 

 and from that ganglion to the gland in the auriculo-temporal nerve. 



Glandulse Submaxillares. The submaxillary glands are next in size to the 

 parotid, and resemble them in their lobulation and colour. Each is placed partly 

 in the submaxillary triangle and partly under cover of the mandible (Fig. 897). 



In each gland two portions may be recognised, a somewhat superficial larger 

 part, the body, lying in the submaxillary triangle, and a smaller deep part, the 

 deep process, which springs from the middle of the deep surface of the body. 



The superficial part, like the parotid, presents a superficial convex surface, 

 which projects below the mandible, in the submaxillary triangle, but it frequently 

 extends beyond the limits of that space, and overlaps the digastric muscle. 



This surface looks downwards and laterally ; it is covered by the deep cervical 

 fascia and the platysma and is crossed superficially by the anterior facial vein. 



Deep to this surface the body of the gland is wedged upwards, between the 

 medial surface of the mandible and the mylo-hyoid and hyoglossus muscles. It 

 thus presents two surfaces, a lateral, which is in contact with the submaxillary 

 fossa of the mandible, and a medial, related to the mylo-hyoid, hyoglossus, the 

 posterior belly of digastric, and stylo-hyoid muscles. 



The deep process passes still further medially, around the posterior free margin 

 of the mylo-hyoid muscle, and comes to lie between the mylo-hyoid and hyoglossus 

 muscles. 



Embedded in the substance of the gland are found a few submaxillary lymph 

 glands, which are of importance from the connexion they have with the lymph 

 vessels of the lip and of a portion of the tongue. 



73 



