DISSECTION OF THE HEAD AND NECK 



223 



extensive than the roof. It is formed by the palatine, superior maxillary, 

 and premaxillary bones, but in much greater proportion by the second 

 of these. 



The Outer Wall is formed by the nasal and superior maxillary bones, 

 and is occupied by the anterior and posterior turbinated bones, which 

 project into the cavity and separate the meatuses of the nose from one 

 another. Thus, the anterior meatus is the narrow interval between the 



Fig. 27. 



Longitudinal Section of the Head, showing the Cavities of the Mouth, 

 Nose, and Pharynx (Leyh). 



1. Frontal sinus; 2. Lateral mass of ethmoid bone; 3. Anterior meatus of nasal chamber; 4. 

 Anterior turbinated bone; 5. Middle meatus ; 6. Posterior turbinated bone ; 7. Posterior meatus ; 

 S. Circumvallate papilla; of the tongue ; 9. Section of soft palate ; 10. Opening of right Eustachian 

 tube on side of pharynx ; 11* Isthmus of the fauces ; 12. Upper aperture of the larynx ; 13. Com- 

 munication between pharynx and oesophagus ; 14. Thyroid gland ; 15. Trachea. 



anterior (ethmoidal) turbinated bone and the roof of the cavity (the 

 nasal bone) ; the middle meatus is another and larger interval between 

 the two turbinated bones ; while the posterior meatus, the largest of these 

 intervals, is included between the posterior (maxillary) turbinated bone 

 and the floor of the cavity. 



The Inner Wall (the septum nasi) is partly bony, and partly cartila- 

 ginous. In its upper part it is formed by the bony perpendicular plate 

 of the ethmoid, and at its posterior edge it is formed by the vomer bone ; 



