V 



THE RESPIRATORY SYSTEM 



THE NOSE 



THE Nasal Septum, which subdivides the nasal cavity into 

 a right and a left half, is partly osseous and partly cartila- 

 ginous. The vomer, which articulates with the sphenoid 

 above and the hard palate below, forms the posterior part of 

 the septum, and its posterior border can be seen on posterior 

 rhinoscopy. Its anterior border articulates above with the 

 perpendicular lamina of the ethmoid, which forms the upper 

 part of the septum, and below with the septal cartilage, which 

 forms the lower part of the septum (Fig. 114). 



When the growth of the individual components of the 

 septum is more rapid than the growth of the septum as a 

 whole, the lines of force meet one another along the articulations 

 and deviation of the septum results. Osseous deviation occurs 

 at the articulation between the vomer and the ethmoid, but 

 cartilaginous deviation may affect any part of the septal 

 cartilage. The former condition does not arise before the 

 seventh year, as, at an earlier date, ossification has not pro- 

 ceeded far enough to bring the two bones into contact. 



On the Lateral Wall of the Nasal Cavity, the three concha 

 (turbinated bones] project downwards and medially and sub- 

 divide the cavity into an inferior, a middle and a superior 

 meatus. The inferior concha forms the roof of the inferior 

 meatus, and, under cover of its anterior extremity, the naso- 



lacrimal duct (p. 208) opens into the nasal cavity. The 



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