THE CARTILAGES OF THE NOSE. 1405 



supplemental pieces (cartilagines minores). The conventional division of the first 

 three, however, is unwarranted, since embryologically and morphologically they 

 constitute one piece (cartilage niediana nasi), which even in the adult is represented 

 by the connected septal and upper lateral plates. 



The cartilage of the septum (cartilago septi nasi) (Fig. 1171) completes the 

 median partition that divides the right and left nasal fossae from each other and 

 represents the anterior extremity of the primordial cartilaginous cranium. It is 

 irregularly rhomboidal in form and so placed that its superior angle lies above, 

 received between the nasal bones and the median plate of the ethmoid, and its 

 inferior angle below, resting upon the incisor crest of the maxillae. The anterior 

 angle is directed forward and the posterior, much the more pointed, is prolonged 

 as the sphcnoidal process (processus sphenoidalis septi cartilaginei) for a variable 

 distance between the mesethmoid and the vomer towards the body of the sphenoid, 

 which exceptionally it may reach. The antero-superior margin of the septal carti- 

 lage, thickest above, is attached to the under surface of the internasal suture for a 



FIG. 1171. 



^Perpendicular plate of ethmoid 



Frontal sinus - 



Septal cartilage 



) 



^~ - Sphenoidal sinus 



Mesial crus of left 



lower lateral cartilage 



Vomerine cartilage" / f HR^IB \ A^' Posterior naris 



; \ 



Sphenoidal process Vomer 



Nasal septum viewed from left side ; mucous membrane has been partially removed. 



distance of from 12-15 mm - Below the nasal bones, the margin of the septal 

 cartilage is continuous with the upper lateral cartilages which form ring-like expan- 

 sions (alae) of the median plate. Still lower, the free-margin of the latter extends 

 between the lower lateral cartilages to within about a half inch from the tip of the 

 nose which, however, it does not reach, the medial crura of the lower lateral plates 

 intervening. The postero-superior margin, the thickest part of the cartilage, is 

 attached to the free margin of the perpendicular plate of the ethmoid bone. The 

 postero-inferior margin rests upon the anterior part of the upper margin of the 

 vomer and the incisive crest as far as the anterior nasal spine, where the border 

 passes into the rounded antero-inferior margin that joins the nasal spine with the 

 anterior angle. This border is always convex and does not reach the lowest part of 

 the partition between the nostrils, which being devoid of septal cartilage, is freely 

 movable and constitutes the septum mobile. 



The upper lateral cartilages (cartilagines nasi laterales) (Fig. 1172) are two 

 triangular plates, one on either side, that by their median and longest border are 

 attached to the septal cartilage, with which in their upper part they are directly 

 continuous. The upper margin of each is joined to the free border of the nasal bone, 

 which it slightly underlies, and, exceptionally, the adjacent edge of the maxilla. The 

 lower margin is embedded in fibrous tissue which connects it with the adjoining plates. 

 The median parts of the cartilages are markedly convex and separated by a slight 

 groove that is, for the most part, obliterated by fibrous tissue. 



