1202 



THE RESPIRATORY SYSTEM 



fellow of the opposite side, but it is separated inferiorly from the septal cartilage 

 by a narrow cleft. The curved supero-lateral margin is firmly attached by strong 

 fibrous tissue to the nasal bone and frontal process of the maxilla, and underlies 

 these bones for a considerable distance, especially near the septum. The inferior 

 margin is connected by fibrous tissue to the greater alar cartilage. The greater 

 alar cartilages [cartilagines alares ma j ores], variable in form, are situated one on 

 each side of the apex of the nose (figs. 961, 963). Each is thin, pliant, curved, 

 and so folded that it forms a medial and a lateral crus, which bound and tend to 

 hold open each naris. The medial crus [crus mediale] is loosely attached to its 

 fellow of the opposite side, the two being situated inferior to the septal cartilage 

 and forming the tip of the nose and the inferior part of the mobile septum. The 

 lateral crus [crus laterale] joins the medial crus at the apex of the nose; it is 

 somewhat oval in shape, and curves dorsally in the superior and anterior portion 

 of the ala. It is connected posteriorly to the nasal margin of the maxilla by a 

 broad mass of dense fibrous and fatty tissue, and helps to maintain the contour 

 of this part of the nose. 



Fig. 964. — Medial Wall of the Nasal Cavity, the Mucous Membrane Being Removed. 

 The dotted line indicates the course of the incisive canal. 



Nasal bone 



Frontal sinus 



Sphenoidal sinus 



Lateral nasal 



Groove between 

 and lateral 

 cartilage 



Greater alar cartilage 



Thickened border of cartilage 

 resting upon anterior nasal spine Incisive 



Orifice of tuba auditiva 



papilla Septal cartilage 



Soft palate 



The angle formed by the crura (angulis pinnalis) varies with the shape of the nose; it aver- 

 ages 30°. The greater and lesser alar cartilages together form an incomplete ring around the 

 naris. 



A variable number of small cartilages, lesser alar cartilages [cartilagines alares minores] 

 are found in the fibrous tissue of the ala, and in the interval between each greater alar and 

 lateral cartilage occur one or more small plates, sesamoid cartilages [cartilagines sesamoideae] 

 (fig. 961). 



The septal cartilage [cartilago septi nasi] (fig. 964) forms the anterior part of the 

 septum. It is quadrilateral in shape and fits into the triangular interval of the 

 bony septum. Its antero-superior margin in its upper part meets the inter- 

 nasal suture. Inferior to the nasal bone it presents a shallow groove which gradu- 

 ally narrows toward the tip of the nose, and whose ])ordcrs are continuous supe- 

 riorly with the lateral nasal cartilages, but are separated from their inferior two- 

 thirds by a narrow slit. The most inferior part of this margin of the septal car- 

 tilage is placed between the greater alar cartilages. The antero-inferior margin 

 extends backward from the rounded anterior angle to the anterior nasal spine. 

 Inferiorly it is attached to the medial crus of the greater alar cartilage and to the 



