Lateral Wall of the Cavum Nasi in Man. 



663 



-i''n.i,lalfvrr 



Frontal fold 



' /5? I T"'' — * ' Frontal fvrrn\ 



Frontal f I, Iti 

 II ^ ■ Frontal fvrrotr 



Frontal rcreH 

 Frontal fnhl 



Frontal I'll 



- — Concha nasalix 

 media 



Fronldlfolil 



Frontal recfuK 



Frontal farroir 



Frontal fold 

 Conrlta nasalix 

 media 

 -Frontal furrov 



ProcesHUS 

 uncinattts 

 Infvndibnlnm 

 etftmoidale 



Ptision 



Fig. 36 (X 8) Drawings of frontal sections through a portion of the lateral 

 nasal wall of a 7-inonths fetus, in the region of the frontal recess (series C, slide 

 5). Section A is farther ventral than is section B. 



Note the blind ventral extremities of the frontal furrows in section A which. 

 at this plane of section, are in reality early anterior ethmoidal cells. Any one of 

 these cells may develop into a frontal sinus, or two may develop sufficiently far 

 to be called frontal sinuses. The frontal recess may also develop into tlie frontal 

 sinus. 



In section B some of the furrows communicate freely with the frontal recess, 

 and at this plane of section are more truly frontal furrows. 



sionally it is well marked and is more or less isolated from the 

 inferior bullar fold by a relatively deep infrabullar furrow. Rarely 

 it retains its identity in the adult — this is especially so when an 

 anterior ethmoidal cell develops from the infrabullar furrow. 



The -processus uncinatus. The processus uncinatus is a con- 

 stant structure, and is medial and inferior to the infundibulum 

 ethmoidale. As was stated before, it is the first of the accessory 

 or hidden conchae to be differentiated. At its ventral and supe- 

 ]ior end it terminates in various ways. In some cases it is continu- 

 ous with one or more frontal folds and at the same time its base 

 continued on to the agger nasi (fig. 41). In other instances it is 

 fused with the lateral surface of the concha media at its ventral 



