DISSECTION OF THE SUBMAXILLARY KEGION. 



comes to 

 side of 

 tongue ; 



use of both 



of one. 



Genio- 

 hyoid : 



relations ; 



Genio- 

 glossus : 



origin : 



insertion ; 



contiguous 

 parts ; 



the styloid process near the apex, and from the stylo-maxillarv 

 ligament, and is directed downwards and forwards to the hinder part 

 of the lateral margin of the tongue. Here it gives some fibres to the 

 dorsum, but the greater part of the muscle turns to the under surface. 

 and is continued forwards to the tip of the tongue. Beneath the jaw 

 this muscle is crossed by the lingual nerve. 



Action. Both muscles will raise the back of the tongue against the 

 roof of the mouth ; and if the tongue be protruded they will restore 

 it to the cavity. 



One muscle can direct the point of the tongue towards its own 

 side of the mouth. 



The GENIO-HYOID MUSCLE (fig. 223, 4 ) arises from the lower of the 



mental spines on the inner 

 aspect of the symphysis o: 

 the jaw, and is inserted into 

 the front of the body of the 

 hyoid bone. 



The lower surface of this 

 muscle is covered by the 

 my lo- hyoid, and the upper 

 is in contact with the genio- 

 glossus ( 3 ). The inner border 

 touches the muscle of the 

 opposite side, and the two are 

 often united. 



Action. The genio-hyoic 

 either depresses the lower jaw 

 or raises the hyoid bone, ac- 

 cording to which end is fixec 

 by other muscles. 



The GENIO-GLOSSUS (genio 

 hyo - glossus, fig. 223, 3 , am 

 fig. 224, A) is a thick, fan- 

 shaped mnscle, having its 

 apex at the jaw, and its base 

 at the tongue. It takes origin 

 from the upper of the mental 



spines behind the symphysis of the jaw. From this spot the fibres 

 radiate, the posterior passing backwards to their insertion into 

 the body of the hyoid bone, the anterior forwards to the tip of 

 the tongue, and the intermediate ones to the tongue from the 

 base to the tip. 



Lying close to the median plane, the inner surface of the muscle 

 is in contact with its fellow. Its lower border corresponds to the 

 genio-hyoid, and the upper to the freenum lingua?. On its outer 

 side are the ranine vessels, and the hyo-glossus muscle ; and the 

 hypoglossal nerve perforates the hinder fibres. 



Action. By the simultaneous action of the whole muscle the 

 tongue is depressed, and hollowed along the middle. The hinder 



FIG. 223. MUSCLES OF THE TONGUE. 



1. Hyo-glossus. 



2. Stylo-glossus. 



3. Genio-glossus. 



4. Genio-hyoid. 



5. Stylo-pharyngeus. 



