THE LATERAL WALL OF THE CAVUM NASI IN MAN, 



WITH ESPECIAL REFERENCE TO THE VARIOUS 



DEVELOPMENTAL STAGES 



JACOB PARSONS SCHAEFFER 



Cornell University Medical College, Ithaca, N. Y. 



Fifty Figures 



CONTENTS 



I. Introduction 614 



II. The formation of the nasal fossae 616 



The nasal anlage 616 



The nasal pits 616 



The primitive nasal fossae 621 



The primitive choanae 622 



The nares (epithelial plugs) 623 



The primitive palate 623 



The definitive palate 624 



The permanent choanae and the permanent nasal fossae 628 



III. The development of the lateral wall of the cavum nasi 629 



The formation of conchal anlages 629 



Views as to the genesis of primitive nasal folds and furrows 630 



The early changes in the meatus nasi medius 633 



The early changes in the meatus nasi superior 635 



The early changes in the superior and dorsal portion of the nasal fossae. 636 

 Thenumberofethmoidalconchae and meatuses that are differentiated 



before birth 636 



Ethmoidal nomenclature 641 



The nasal meatuses and conchaein late fetal stages 642 



The accessory folds (conchae) and furrows 655 



IV. The anlages of the sinus paranasales 669 



The sinus maxillaris 674 



The sinus frontalis 676 



The cellulae ethmoidales 679 



The sinus sphenoidalis 680 



V. Later developmental changes on the lateral nasal wall 681 



The number of ethmoidal conchae in the adult 681 



The ethmoid cells and their ostia 684 



The conchal cells • 686 



The ostia maxillaria 688 



The communication of the frontal sinus with the middle meatus. . . . 694 



VI. Summary 699 



Bibliography 705 



JODBNAL OF MoRPHOI-OGT, VoL. 21, NO. 4. 



