83 SURGICAL APPLIED ANATOMY. [Chap. vi. 



This mode of examination is very difficult to carry 

 out, and is known as posterior rhinoscopy. The parts 

 just named can all be felt \>y the finger introduced 

 behind the soft palate through the mouth. The 

 posterior nares are often plugged to arrest severe 

 bleeding from the nose, and in order to cut a proper 

 sized plug it is desirable to bear in mind the dimen- 

 sions of the apertures. Each aperture is of regular 

 shape, and measures about half an inch transversely 

 by one and a quarter inches in the vertical direction 

 in a well-developed adult skull. 



As regards the nasal cavities generally, it is 

 well to note that the floor is wider at the centre 

 than at either end, that the vertical diameter is 

 greater than the transverse, and is greatest also about 

 the centre of the fossae. Forceps introduced into the 

 nose, therefore, are most conveniently opened if 

 opened vertically. The width of the fossae increases 

 somewhat from above downwards, thus the superior 

 turbinated bone is only 2 mm. from the septum, 

 while a space of from 4 to 5 mm. intervenes between 

 the inferior turbinated bone and the septum. The 

 nasal cavity is so very narrow above the middle 

 turbinated bone that that bone really forms the 

 surgical roof of the nasal fossae. 



From a reference to the relations of the nasal 

 fossae, it will be understood that inflammation of the 

 lining membrane (coryza) may extend to the pharynx 

 via the posterior nares ; may extend up the Eusta- 

 chian tube and cause some deafness ; may reach the 

 lachrymal sac and conjunctiva through the nasal 

 duct ; and may extend to the frontal sinuses and the 

 antrum, producing frontal headache and cheek-ache. 

 These relationships are often demonstrated in a severe 

 " cold in the head." From the nearness of the nasal 

 fossa? to the cranial cavity it happens that meningitis 

 has followed upon purulent inflammations of the nose. 



