1258 



A MANUAL OF ANATOMY 



of which it is composed are of three kinds, (i) Long columnar 

 nucleated cells, called the sustentacular cells, the deep ends of 

 which are prolonged each into a branched process. (2) Between 

 these sustentacular cells there are the olfactory cells, which are 

 elongated and spindle-shaped. Each contains an almost spherical 

 nucleus, and has a superficial and a deep process or pole. The 

 superficial pole extends through the limiting membrane to the free 

 surface, and projects slightly in the form of a tuft of delicate hair- 

 like filaments called the olfactory hairs. The deep pole, which is a 

 delicate varicose filament, extends towards the mucosa, where it 

 becomes continuous with one of the nerve-fibrils of the olfactory 



Olfactory Filaments 



Olfactory Bulb / 



Olfactory Tract 



Fig. 516A. — The Nerves of the Nasal 

 Septum (Hirschfeld and Leveille). 



Fig. 5 1 6b. — Cells of Olfactor- 



Mucous Membrane (Schultzi 

 FROM Quain's 'Anatomy ')• 



plexus. (3) In the deep part of the epithelium there are in some 

 places conical cells, the broad ends of which rest upon the basement 

 membrane. • 



Olfactory Nerves. — ^These are from fifteen to twenty in number 

 on each side. After leaving the inferior surface of the olfactory 

 bulb, they pass through the foramina in the corresponding half of 

 the cribriform plate of the ethmoid bone, and so reach the upper 

 part of the nasal fossa, invested by prolongations of the membranes 

 of the brain. Within the nasal fossa they are arranged in two groups, 

 inner and outer. The nerves of the inner group are distributed' 

 to the mucous membrane of the septum nasi over about its upper 

 third. The nerves of the outer group are distributed to the mucous 

 membrane in the region of the superior concha and olfactory sulcus. 

 The nerves form a copionr. plexus in the mucous membrane, and 

 the filaments which issue from this plexus become continuous, as 



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