670 



Meatuses. 



Upper 

 meatus. 



DISSECTION OF THE NOSE. 



Between each turbinate bone and the wall of the nose is a 

 longitudinal hollow or meatus; and into these hollows the nasal 

 duct and the sinuses of the surrounding bones open. 



The meatuses are the spaces arched over by the spongy bones ; and 

 as the bones are limited to a certain part of the outer wall, so are 

 the spaces beneath them. 



The upper meatus (fig. 236, 6 ) is the smallest and straightest of the 

 three, and is limited to the posterior half of the space above the 

 hard palate. Into its fore part the posterior etlnnoidal cells open 

 (figs. 235 and 237), and at its posterior end, in the dried skull, is 



j'rontai surma 



irvftmdib. 



mid . etkm. cells 



post, etlim. ccllg 



Am. rcc. 



gphen. sinus 



vestit. 



at. rec. 

 East. tul>e 



antrrun 



nasal J.uct | Hiahw semilun. 

 ant. ethtn. cells. 



FIG. 237. OUTER WALL OF RIGHT NASAL FOSSA. 



The whole of the middle, and the fore part of the lower turbinate bones 

 have been cut away, to show the openings in the middle and inferior 

 meatuses. 



the spheno-palatine foramen by which nerves and vessels enter the 

 nose. 



The middle meatus f (fiv. 236, 7 ) is longer than the upper, and reaches 

 from the posterior opening of the nasal fossa, nearly as far forwards 

 as the hard palate. The free border of the middle turbinate bone 

 being curved upwards anteriorly, this meatus is open in front as well 

 as below. On raising, or cutting away, the overhanging turbinate 

 bone (fig. 237), a deep groove, hiatus semilunaris, will be seen in the 

 fore part of the lateral wall of the meatus, bounded below by the 

 uncinate process of the ethmoid, arid leading upwards through the 

 infundibulum of the latter bone to the frontal sinus. Into the 

 groove lower down the anterior ethmoidal cells open, and at its 

 hindmost part is a small aperture leading into the antrum of the 

 superior maxilla. Above the hiatus is a crescentic enlargement (the 

 Ethmoidal ethmoidal bulla)j above which is an opening leading into the middle 



bulla. 



Middle 

 meatus. 



Hiatus 

 semilunaris. 



