THE NECK, ANTERIOR. 81 



The Mylohyoid Nerve. Figs. 12, 17. 



This is a small branch from the inferior dental just before 

 it enters the dental foramen in the lower jaw. It runs 

 downward and forward, grooving the under surface of the 

 lower jaw, and supplies the mylohyoid and anterior belly 

 of the digastric muscles. In its course across the mylo- 

 hyoid muscle it is accompanied by the submental branch 

 of the facial artery. 



Mylohyoid. Fig. 17. 



Origin. From the mylohyoid ridge on the inner surface 

 of the inferior maxilla. 



Insertion. Into the body of the hyoid bone, and a 

 median raphe extending from the hyoid bone to the lower 

 jaw. 



Nerve Supply. The mylohyoid branch of the inferior 

 dental (of inferior maxillary). 



Action. To raise the hyoid bone, and the parts con- 

 nected to it, especially the tongue. To depress the lower 

 jaw if the hyoid bone is fixed. 



Having dissected out the preceding muscles, replace 

 the sternomastoid and take up the study of the triangles 

 of the neck, their formation or boundaries, the muscles or 

 parts which form their floor, and most especially their va- 

 rious contents and their relations to each other. 



The Triangles of the Neck. Figs. 16, 17. 



The side of the neck forms an irregular parallelogram 

 with the following boundaries. 



Above, by the lower border of the inferior maxilla, the 

 mastoid process of the temporal bone, and a line joining 

 the angle of the jaw with the mastoid process. 



In front, by the median line. 



Below, by the top of the manubrium and the clavicle. 

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