INTRODUCTION TO NEUROLOGY 



Olfactory 

 hairs 



.Olfactory 

 hairs 



Peripheral 

 "process 



Body of 



-cell with 



nucleus 



Central 

 process 



C 



Fig. 36. Cells from the olfactory mucous membrane: A from the frog, 

 B and C from man. The supporting cells are non-nervous. The olfactory 

 hairs of the olfactory cells project out "into the mucus of the nose, and are 

 probably the specific receptors. The central process at the base of each 

 olfactory cell is prolonged mto a fiber of the olfactory nerve (not shown 

 in the figure), which extends inward to the brain (cf. Fig. 104, p. 217). 

 (After Schnlte and Brunn.) 



the primitive interoceptive, though the latter has by no means been en- 

 tirely obliterated. 



m. SOMATIC EFFECTORS 



24. End-organs on Striated Skeletal Muscles. This "motor end- 

 plate" is a complex terminal arborization of the motor nerve-fiber, associ- 

 ated with an elevated granular mass of protoplasm and a collection of 

 nuclei of the muscle-fiber (see Fig. 5, tel, p. 40). 



The somatic muscles whose innervation is here under consideration are 

 derived embryologically from the somites, or primary mesodermal segments 

 of the embryo, while the visceral muscles have a different origin. They are 

 under the direct control of the will and are concerned chiefly with loco- 

 motion or other movements which change the relations of the body to its 

 environment. They are typically stimulated to action through the ex- 

 teroceptive sense organs. They make up the bulk of the musculature of 

 the trunk and limbs and are represented in the head only in the external 

 muscles of the eyeball and a part of the muscles of the tongue. 



