THE MOUTH AND THROAT. 



109 



is usually restricted to those of the submaxillary and sublingual glands. The 

 mylohyoicl muscle forms the floor of the mouth and these cysts lie on it beneath 

 the tongue and between the tongue and the gums (Fig. 136). If the cyst is large it 

 causes a protrusion or swelling beneath the jaw. The bulk of the submaxillary gland 

 lies on the side of the mylohyoid muscle nearest the skin; only a small portion of it 



Fraenum 



Sublingual ridge 



Orifice of 

 sublingual and 

 submaxillary ducts 



FIG. 135. Under surface of tongue and floor of mouth. 



winds around the posterior edge of the muscle. Therefore, cysts involving the sub- 

 stance of the gland would show in the submaxillary region of one side. If, however, 

 the duct were obstructed (as by a calculus) it would form a cyst, which would bulge 

 into the mouth beneath the tongue and be called a ranula. The sublingual gland is 

 usually the starting point of these cysts, and it will be seen that as they enlarge they 



FIG. 136. Sublingual cyst (ranula). (From a photograph by Dr. Ashhurst.) 



push the ranine artery with the tongue backward and are only covered by the mucous 

 membrane. On this account there is little or no danger in operating on them. 

 They are either dissected out or the front wall of the cyst cut away and the interior 

 cauterized or packed with gauze to promote the formation of granulations. The 

 jaw-bone is in front of them and the mylohyoid muscle beneath. Posteriorly lies the 

 duct of the submaxillary gland and the ranine artery. 



