HEAD AND NECK IN SECTION ii 



two turbinated bones near their posterior extremity is necessary, and it 

 will thus be gathered that any surgical attempt to communicate with 

 the sinuses through the nostrils by way of this natural opening would 

 be attended with considerable difficulty. 



The Schneiderian Membrane (frequently called the pituitary 

 membrane) is the mucous lining of the nasal chamber. In the posterior 

 fourth of the cavity this membrane is of a slightly yellowish colour- 

 This is the portion to which the olfactory nerve is distributed, and it is 

 therefore the area of the sense of smell. The remainder of the mem- 

 brane is much more vascular in appearance, and is lined by columnar 

 ciliated epithelium, which is found throughout the air passages generally. 

 In the olfactory portion of the membrane we also find columnar 

 epithelium ; but the cells are not ciliated, and between them are placed 

 the peculiar spindle-shaped cells which contain the end organs of the 

 sense of smell. 



The filaments of the olfactory nerve enter the nasal chamber through 

 the perforations in the cribriform plate of the ethmoid bone. These 

 perforations thus form in the mascerated and dry skull a communication 

 between the cranial and nasal cavities. 



Below the palate is the cavity of the mouth. The examination of 

 the roof of this chamber will reveal the presence of a number of curved 

 parallel ridges. The concavity of the curves is directed backwards, and 

 as we proceed in the posterior direction the ridges approximate more 

 closely to one another. Two sets of ridges will be noticed, one on 

 either side a median raphe, from which the ridges curve outwards. 

 In the plate, therefore, only the sections of the extremities of the 

 series of ridges covering the right half of the palate are represented. 



Running along the palate, one on either side and placed under- 

 neath the ridges which have just been described, and near their outer 

 extremities, we have the palatine arteries. Each of these vessels is the 

 continuation of the internal maxillary artery of the same side. It 

 commences where the latter splits up in the maxillary hiatus, and the 



