PART III. 



CHAPTEK XXII. 



THE NASAL FOSSJE, PHARYNX, AND TONSILS. 



BY D. BRYSON DELAVAN, M.D. 



Curator of the New York Hospital, New York City ; Member of the American Laryn- 



gological Association. 



The vestibulum nasi is that part of the nasal canal which 

 is surrounded by the anterior cartilages of the nose. It is cov- 

 ered by a continuation of the exterior skin, which gradually 

 assumes the characteristics of a mucous membrane and pos- 

 sesses several layers of pavement-epithelium, the uppermost 

 of which is composed of horny cells. This epithelium extends 

 backward to the anterior margin of the inferior turbinated 

 bone and the commencement of the inferior nasal duct, where 

 it becomes ciliated. The integument has also vascular papillae, 

 with both simple and compound loops, and in the lower part 

 of the nose long, stiff hairs (vibrissae), as well as large sebaceous 

 follicles. It is sparingly supplied with blood-vessels. The 

 nerves are derived from the trigeminus, and consist of fila- 

 ments, which probably end in terminal bulbs. 



The respiratory region. The nasal fossae proper, with the 

 exception of a limited part known as the olfactory region, may 

 be regarded as a continuation of the respiratory tract. Each 

 fossa communicates with four sinuses : the frontal, the sphe- 

 noidal, the maxillary or antrum Highmorianum, and the pos- 

 terior ethmoidal. The mucous membrane covering the respira- 

 tory region and its accessory sinuses is called the Schneiderian 

 or pituitary membrane. It is devoid of papillae, and is covered 

 with a cylindrical ciliated epithelium, like that of the trachea, 



