32 PRACTICAL ANATOMY. 



The levator labii superioris covers the infraorbital nerve and artery. This 

 muscle arises from the margin of bone below the orbit. (Fig. 10.) It is inserted 

 into the orbicularis oris. 



The levator anguli oris arises from the canine fossa below the infraorbital 

 foramen. It is inserted into the angle of the mouth. It may be seen by pulling 

 the leash of nerves to one side. The leash of nerves lies between the above two 

 muscles. (Fig. 10.) 



The Depressor Labii Inferioris. Remove the skin a little further in the 

 region of the mental nerves, and find the depressor of the lower lip. This 

 muscle is quadrangular in form. Fully one-half of its outer surface lies under 



\ 



\ 



FIG. 12. PRIMARY INCISIONS IN DISSKCTION 01 THE KACK. 



the depressor anguli oris (Fig. 13). The muscle arises from the upper part of the 

 external oblique line of the mandible, and is inserted into the lower lip. 



The depressor anguli oris (Fig. 13) will be found arising from the lower part 

 of the external oblique line of the mandible. It is triangular in form. It over- 

 laps the outer one-half of the depressor labii inferioris. Now cut the origin of 

 this muscle, and pull the same aside and expose the whole of the muscle that 

 it overlaps. (Fig. 17.) 



CAUTION. In all dissections about the face care must be taken to cut close 

 to the skin. The branches of the seventh nerve lie beneath the muscles and 

 can not be injured if you take the precaution just given. 



