THK NASAL FOSSAE 



1085 



longed, above and in front, into the infundibulum, which leads into the frontal 

 sinus. The anterior extremity of the meatus is continued into a depressed area 

 which lies above the vestibule and is named the atrium (atrium meatus medii iiasi). 

 The nasal duct opens into the anterior part of the inferior meatus, the opening 

 being frequently overlapped by a fold of mucous membrane. 



The Inner Wall (Fig. 792). The inner wall or septum is frequently more or 

 less deflected from the mesal plane (Figs. 104 and 792), thus limiting the size of 

 one fossa and increasing that of the other. Ridges or spurs of bone growing out- 

 ward from the septum are also sometimes present. Immediately over the incisive 

 foramen at the lower edge of the cartilage of the septum a depression, the naso- 

 palatine recess (recessus nasopalatinus), may be seen. In the septum close to this 



Eye-ball 



Groove (hiatus semilunarus) 

 leading to infundibulum 

 Middle turbinatcd bone 



Middle meatus 

 Antrum of Highmore 

 Inferior meatus 



Inferior turbinated bone 



( Buccal cavity 



I Space between cheek and yum 



Molar tooth, upper jaw 



Root of molar tooth 



nferior dental nerve 



Tonfjue I Hard palate 



Septum 

 nasi 



FIG. 792. Transverse vertical section of the nasal fossae. The section is made anterior to the superior 



turbinated processes. (Cryer.) 



recess a minute orifice may be discerned; it leads into a blind pouch, the rudimen- 

 tary organ of Jacobson (oryanon vameronasale), which is well developed in some 

 of the lower animals, but is rudimentary in man. The organ is supported by a 

 plate of cartilage, distinct from the cartilage of the septum, the cartilage of Jacob- 

 son (p. 1082). The cartilage of Jacobson is to the outer side of the lower edge of 

 the cartilage of the septum. Just below the opening of the blind pouch is an 

 elevation, the eminence of Jacobson. 



The Mucous Membrane (membrana mucosa nasi}. The mucous membrane lining 

 the nasal fossae is sometimes called the Schneiderian membrane. 1 It is intimately 

 adherent to the periosteum or perichondrium, upon which it lies. It is continuous 



1 After Conrad Victor Schneider O614-1680\ Professor of Anatomy at Wittemberi?. 



