THE SUPRAHYOID REGION 



391 



bone. The middle and anterior fibres are inserted into a median fibrous raphe, 

 extending from the symphysis of the mandible to the hyoid bone, where they 

 join at an angle with the fibres of the opposite muscle. The median raphe' is 

 sometimes wanting; the muscle fibres of the two sides are then directly continuous 

 with one another. 



Relations. By its superficial surface, with the Platysma, the anterior belly of the Digastric, 

 the suprahyoid aponeurosis, the submaxillary gland, submental vessels, and mylohyoid vessels 

 and nerve; by its deep surface, with the Geniohyoid, part of the Hyoglossus and Styloglossus 

 muscles, the hypoglossal and lingual nerves, the submaxillary ganglion, the sublingual gland, 

 the deep portion of the submaxillary gland and duct; the sublingual and ranine vessels, and 

 the buccal mucous membrane. 



FIG. 303. Muscles of the tongue. Left side. 



Dissection. The Mylohyoid should now be removed, in order to expose the muscles which 

 lie beneath ; this is effected by reflecting it from its attachments to the hyoid bone and mandible, 

 and separating it by a vertical incision from its fellow of the opposite side. 



The Geniohyoid (m. geniohyoideus) (Fig. 303) is a narrow, slender muscle, 

 situated immediately beneath 1 the inner border of the Mylohyoid. It arises from 

 the inferior genial tubercle on the inner side of the symphysis of the mandible, and 

 passes downward and backward, to be inserted into the anterior surface of the 

 body of the hyoid bone. This muscle lies in close contact with its fellow of the 

 opposite side, and increases slightly in breadth as it descends. 



Relations. It is covered by the Mylohyoid and lies along the lower border of the Genio 

 hyoglossus. 



1 This refers to the depth of the muscles from the skin in the order of dissection. In the erect position of 

 the body the Geniohyoid is above the Mylohyoid. 



