Lateral Wall of the Cavum Nasi in Man. 



633 



The early changes in the meatus nasi medius 



Thus far only the superficial aspects of the lateral nasal wall, 

 with especial reference to the development of folds and furrows 

 (conchae and meatuses), have been considered. The general plan 

 of these conchae and meatuses will be considered in detail in 

 subsequent paragraphs. If now we return to a 40- to 50-day 



FoMa cra»ii anterior 



Latenil plnte of 

 cartilatfe 



^eaftts itaMi 



, inferior 



Cleft rnmmiinirating 

 between the nasal and ^^^^ 

 oral earitieg before \ 



completion of the de- \ 

 finitire palate 



Septtnn nasi 



Meatus nasi 

 " rnmmnnis 



Concha nasalis 

 media 



Mfatiis nasi 



ntcditts 



Concha nasalis 

 inferior 



J^roccHstis palalinus 



Fig. 16 (X 26.6) Outline drawing of a frontal section of the nasal cavity of 

 an embryo aged approximately 49 days (Human embryo, No. 28, Cornell Uni- 

 versity series, slide 48). The nasal and oral cavities are in communication with 

 each other at this point, i.e., the palatal processes have not as yet coalesced in 

 the median plane in the formation of the definitive palate. Note also the simple 

 lateral wall of the middle nasal meatus — compare with fig. 18. 



embryo and examine the portion of the middle meatus opercu- 

 lated by the middle nasal concha, we will notice that the lateral 

 wall of this meatus is perfectly even (fig. 16). This study is best 

 made by an examination of serial frontal sections through this 

 region of the nose. This same region in an embryo aged from 58 



JOUBNAl OF MORPHOLOQT, VOL. 21, NO. 4. 



