NASAL CAVITY. 



801 



suture ; immediately below the level 

 of the nasal bones it is continued, on 

 each side, into the lateral cartilages, 

 which may be looked upon as its 

 wing-like expansions. The inferior 

 part of this border is separated by 

 a fissure from the , lateral cartilage, 

 and extends downwards between the 

 greater alar cartilages, to which it is 

 attached by fibrous tissue; in this 

 fibrous tissue a small accessory car- 

 tilage is usually seen on either side 

 of the median plane. Its antero- 

 inferior border is short, and is at- 

 tached by fibrous tissue to the medial 

 crura of the greater alar cartilages, 

 while its anterior angle is rounded 

 and does not reach as far as the 

 apex of the nose. The lowest part 

 of the nasal septum is not formed 

 by the septal cartilage, but by the 

 medial crura of the greater alar 

 cartilages and by the integument, 

 and, being freely movable, is termed 

 the septum mobile nasi. The cartilage 

 of the septum may be prolonged 

 backwards (especially in children) 

 as a narrow process, the processus 

 sphenoidalis, into the angle between 

 the vomer and ethmoid ; this process 

 varies from 4 to 6 mm. in width, and sometimes reaches as far as the body of the 

 sphenoid. 



On either side of the inferior 

 edge of the cartilage of the septum, 

 and seen best in a frontal section 

 of the nose, is a narrow band of 

 cartilage, the vomero-nasal cartil- 

 age ; it measures from 6 to 12 mm. 

 bone in length, and is attached to the 

 vomer. 



FIG. 669. PROFILE VIEW OF THE BONY AND CARTI- 

 LAGINOUS SKELETON OF THE EXTERNAL NOSE. 



Frontal pr 

 of maxilla 



CAVUM NASI. 



septum 



Accessory 

 cartilage 

 Greater alar 

 cartilage 

 Lateral crus 

 ~ Medial crus 



FIG. 670. 



FRONT VIEW OF THE BONY AND CARTILAGINOUS 

 SKELETON OF THE EXTERNAL NOSE. 



Lateral cartilage The nasal cavity (Fig. 672) is 

 cartilage of divided by the nasal septum into 

 a right and a left nasal cavity, 

 which extend from the nostrils in 

 front to the choanse behind, and 

 open, through the choanse, into the 

 nasal part of the pharnyx. Their 

 bony boundaries are described in 

 the section on Osteology (p. 183). 

 On the lateral wall of each are 

 found the orifices of the frontal, 

 ethmoidal, sphenoidal, and maxil- 

 lary sinuses, together with that of 

 the naso-lacrimal duct. 



Immediately above the aper- 

 ture of the nostril is a slightly 

 52 



