96 



MOUTH. 



first joint of the fourth and fifth toes. Insertion, into the external 

 sesamoid bone. Use ; it approximates the heads of the metatarsal 

 bones. 



Interosseous Muscles. — These are seven in number, four of which 

 are upon the dorsal, and three upon the plantar surface of the foot. 

 The dorsal interossei arise by double heads, and are inserted into the 

 base of the first phalanx. The plantar interossei arise from the 

 bases of the three outer metatarsal bones, and are inserted into the 

 inner side of the base of the first phalanx of the same toes. 



Fig. 77. Fig. 78. 



SECTION IV. 

 VISCERA. 



ORGANS OF DIGESTION. 



MOUTH. 



The Mouth is separated from the nose by the hard and soft palate, 

 communicating behind with the fauces ; it is bounded in front by the 

 lips, while its floor is formed by the mylo-hyoid muscles ; and its 

 sides by the cheeks ; the space between the lips and the teeth is 

 called the vestibule ; it is lined by a mucous membrane, which has 

 a variable degree of thickness. This membrane is thrown into 

 folds, which are called frena ; there is one beneath the tongue, one 

 beneath the epiglottis cartilage at the root of the tongue, and one 



