SUB MAXILLARY REGION. 47 



branches throughout its substance ; its duct, called Wh.ar- 

 torfs duct, may be seen issuing from its posterior part, and 

 curving around the posterior border of the mylo-hyoid 

 muscle, passes between the hyo-glossus and genio-hyo- 

 glossus muscles and beneath the sublingual gland, to open 

 at the side of the frenum of the tongue. 



The MYLO-HYOID MUSCLE arises from the mylo-hyoid ridge 

 of the inferior maxillary bone, and its posterior fibres pass 

 forward to be inserted into the body of the os hyoides; 

 the anterior fibres join with those of the muscle of the 

 other side, forming a sort of raphe along the median line ; 

 it is triangular in shape, and with its fellow makes the 

 floor of the mouth, the two muscles stretching across the 

 interval between the two sides of the lower jaw. The 

 mylo-hyoid branch of the inferior dental nerve ramifies 

 upon its cutaneous surface, as well as a twig from the in- 

 ternal maxillary artery, which accompanies that nerve. 

 The submental branch of the facial artery also ramifies 

 upon this muscle. 



The mylo-hyoid muscle is to be carefully removed or turned down 

 toward the hyoid bone. 



The GTENIO-HYOID MUSCLE lies close to the median line, 

 and arises from the inside of the symphysis of the lower 

 jaw ; it is inserted into the centre of the body of the hyoid 

 bone, in close apposition with the muscle of the other side, 

 with which it is often united. 



The hyo-glossus and genio-hyo-glossus will be found described in 

 connection with the tongue. 



If the snbmaxillary gland has been preserved, Wharton's 

 duct may be seen resting upon the hyo-glossus muscle. 

 The hypoglossal nerve crosses that muscle, and in this 

 part of its course gives off the descendens noni branch 

 to the sheath of the carotid vessels (p. 41). By drawing 

 the os hyoides downward the gustatory branch of the in- 

 ferior maxillary nerve will also be found resting upon the 

 hyo-glossus muscle. The submaxillary ganglion, a small 

 reddish body, is in close connection with the gustatory 

 nerve, and lies just above the upper border of the sub- 

 maxillary gland; it is extremely difficult to find. The 

 chorda, tympani, a branch of the facial nerve which joins 

 the gustatory nerve near the submaxillary ganglion, may 

 also be seen at this point of the dissection. 



