374 



ANATOMY FOR NURSES [Chap. XIX 



of communication between : (1) the different parts of the nervous 

 system, (2) the nerve centres and the viscera, (3) the nerve centres 



and the periphery, and (4) 

 the viscera and the surface 

 of the body. 



Between the nerve- 

 fibres is a small amount 

 of connective tissue which 

 serves not only to bind 

 the fibres together into 

 bundles, or funiculi, but 

 also to carry to or from 

 the fibres the blood-vessels 

 and the lymphatics nec- 

 essary for their imtrition. 

 Connective tissue also 

 surrounds these bundles 

 in the form of a sheath. 



Although the nerves 

 branch frequently through- 

 out their course, and these 

 branches often meet and 

 fuse with one another, or 

 with the branches of other 

 nerves, yet each nerve- 

 fibre always remains quite 

 distinct, never branching 

 until it reaches its ter- 

 mination, and never unit- 

 ing with other nerve-fibres. 

 The nerve-trunk is thus merely an association of individual 

 fibres which have very difTerent activities and which may func- 

 tion entirely independent of one another. Perhaps the best idea 

 of the arrangement of ner\'e-fibres in a trunk can be obtained from 

 a cross-section of a nerve such as is seen in Figure 179. 



Nerve centres. — Groups of nerve-cells exercising control over 

 some definite function are called centres. Each of these centres 

 is influenced by impulses from various parts of the body which 

 travel along special nerves to these centres. Many of these cen- 



FiG. 178. — Diagram 

 General Arrangement of 

 SPINAL System. 



ILLUSTRATING THE 

 THE CeREBRO- 



