Lateral Wall of the Cavum Nasi in Man, 643 



The nasal meatuses 



The meatus nasi inferior. The meatus nasi inferior is one of the 

 first meatuses to become well established. It is primitively formed 

 between the anlage of the concha inferior and the primitive proces- 

 sus palatinus. Later, with the fusion of the two palatal processes in 

 the median plane to form the definitive palate, the meatus inferior 

 comes to occupy the position between the concha inferior and the 

 floor of the nasal fossa. The ductus nasolacrimalis connects 

 with the meatus inferior approximately at term. A reference to 

 fig. 37 will, however, show a frontal section of the left nasal fossa 

 of a term fetus in which the barrier between the meatus inferior 

 and the ductus nasolacrimahs is still intact, i.e., the duct has not 

 acquired a lumen in the region of the meatus inferior. Finally 

 there are two layers of abutting epithelium, one nasal and the 

 other that of the duct, forming the barrier. The membrane now 

 seems to thin out and to become attenuated, ultimately rupturing; 

 in other words the duct becomes patent at this point. This 

 attenuation of two layers of abutting epithelium, ultimately 

 resulting in rupture, in order that communication between two 

 cavities may be established, reminds one somewhat of the atten- 

 uation and rupture of the membrana bucconasalis. 



The meatus nasi inferior is otherwise simple and offers no con- 

 ditions that warrant a further consideration at this time. 



The meatus nasi 7nedius, superior, suprema I, suprema II, 

 suprema III. The ethmoidal meatuses, including the meatus 

 medius — since they have many things in common- — may for 

 the time be considered together. It must be recalled that 

 in many cases the meatus suprema I, II, and III are extremely 

 rudimentary, and are merely very shallow, short grooves. Again 

 in many instances the meatus nasi suprema II and III are not at 

 all differentiated. The meatus nasi suprema I is the most cbn- 

 stant of the supreme meatuses. While we must follow some gen- 

 eral type for the sake of description, it does not necessarily 

 indicate that all specimens agree in their entirety. 



The ethmoidal meatuses all converge at their inferior and dorsal 

 extremities in the region of the angle formed by the junction 



