THE ANTERIOR REGION OF THE SKULL. 



117 



into a recess, the spheno-ethmoidal recess, which is situated above and behind the 

 superior turbinated bone. The middle meatus is situated between the middle and 

 inferior turbinated bones, and extends from the anterior end of the inferior 

 turbinated bone to the spheno-palatirie foramen of the outer wall of the nasal 

 fossa. It presents in front the orifice of the infundibulum , by which the middle 

 meatus communicates with the anterior ethmoidal cells, and through these with 

 the frontal sinuses. The middle ethmoidal cells also open into this meatus, while 



Crest of nasal bone 



Nasal spine of 

 frontal bone. 



Space, for triangular^ 

 cartilage of septum 



Crest of palate bone. 

 /il Crest of superior maxillary 

 bone. 



FIG. 77. Inner wall ot nasal fossse, or septum of nose. 



at the centre of the outer wall is the orifice of the antrum, which varies somewhat 

 as to its exact position in different skulls. The inferior meatus, the largest of 

 the three, is the space between the inferior turbinated bone and the floor of the 

 nasal fossa. It extends along the entire length of the outer wall of the nose, is 

 broader in front than behind, and presents anteriorly the lower orifice of the 

 canal for the nasal duct. 



The anterior nares present a heart-shaped or pyriform opening whose long 

 axis is vertical and narrow extremity upward. This opening in the recent state 

 is much contracted by the cartilages of the nose. It is bounded above by the 

 inferior border of the nasal bone; laterally by the thin, sharp margin which 

 separates the facial from the nasal surface of the superior maxillary bone ; and 

 below by the same border, where it slopes inward to join its fellow of the opposite 

 side at the anterior nasal spine. 



The posterior nares, or choanae, are the two posterior oval openings of the nasal 

 fossse, by which they communicate with the upper part of the pharynx. They are 

 situated immediately in front of the basilar process, and are bounded above by the 

 under surface of the body of the sphenoid and alse of the vomer ; below, by the 

 posterior border of the horizontal plate of the palate bone ; externally, by the inner 

 surface of the internal pterygoid plate ; and internally, in the middle line, they 

 are separated from each other by the posterior border of the vomer. 



