THE NOSE OK ORGAN OP SMELL. 381 



dary. At the point of the nose, these cartilages are thick 

 and constitute the tip, or lobe ; each passes round the ori- 

 fice of the nostril, in a semicircular form, having its in- 

 ternal surface deeply concave, hy which the nostrils are 

 enlarged. As they make their curve, they become widened 

 at their posterior part, by having, as appendages, three or 

 four small cartilaginous plates connected by fibrous tissue. 

 The two alar cartilages meet, in front, beneath the septum, 

 and are attached, by fibro-cellular tissue, to the nasal spine 

 of the superior maxillary bones, forming a projection called 

 the columna. All these cartilages are connected, by fibrous 

 tissue, to one another and to the bones, and are readily 

 movable, by the muscles attached to them, so as to enlarge 

 or contract the anterior nares at pleasure. 



Each nostril has its entrance protected by some stiff 

 hairs, called vibrissce, which prevent the introduction of 

 foreign bodies, along with the air, in breathing. 



The integument of the nose is thick and dense, and so 

 closely attached to the cartilages, as with difficulty to be 

 separated from them. It is supplied with numerous seba- 

 ceous follicles, whose ducts open upon the surface and fre- 

 quently present the appearance of numerous black dots, 

 from the presence of carbon. This sebaceous secretion be- 

 comes solidified, and, by pressing the follicles, can be forced 

 out in fine, long threads, which have been compared to 

 "small, white maggots with black heads." These follicles 

 are liable to hypertrophy, and occasionally become so large 

 as to present a very tuberculated and unsightly appear- 

 ance. 



The use of this secretion, which is of an oily nature, is 

 to preserve the skin of the nose in a soft and pliable con- 

 dition, as well as to guard against excessive changes in 

 temperature. 



Nasal Fossa, (Fig. 111.) The nasal fossce constitute the 

 internal or posterior part of the nose, forming its second di- 

 vision. They consist of two very irregular cavities extend- 

 ing back to the pharynx, and bounded above by the nasal 

 cartilages, nasal, frontal, cetTimoidal, and sphenoidal bones, 



