188 



HEALTH AND DISEASE 



Pterygoid Bones. These are two small slender bones placed imme- 

 diately above the palate bones. 



On the outer side of each is a groove or pulley, through which a small 

 tendon plays, belonging to the muscle (tensor palati) that tightens up 

 the palate in the act of swallowing. 



The Vomer. A single bone running along the whole length of the 

 floor of the nasal cavities, where it occupies a central position. Its anterior 

 border is deeply grooved, and gives lodgment to a flat piece of cartilage 



Fig. 290. Lower Jaw 



1 Coronoid Process. 2 Condyle. 3 Molar Teeth. 4 Mental Foramen. 6 Incisor Teeth. " Surface for 



attachment of Masseter Muscle. 



(septum nasi) by which the nasal passages are divided one from the 

 other. 



Turbinated Bones. These are four in number, two situated in each 

 nasal passage, where they are attached to the outer walls one above the 

 other. They are long, thin, fragile plates of bone, folded upon themselves 

 into rolls, which extend nearly from one extremity of the nose to the 

 other. They are covered with mucous membrane, and afford a large 

 surface for the distribution of the nerves of smell (olfactory nerves), and 

 for the secretion of mucus. 



Inferior Maxillary Bone or Lower Jaw. This is a single bone 



composed of two flattened branches, which converge from above down- 

 ward, and unite in front to form the body. It is the largest bone of 



