208 ANATOMY AND PHYSIOLOGY FOR NURSES 



4. Mixed Nerves. These contain both motor and sen- 

 sory fibers. They are the inferior maxillary division of the 

 fifth, the tenth pair of cranial nerves, and all of the spinal 

 nerves. 



5. The Sympathetic Nerve. The sympathetic nerve, 

 also called the trisplanchnic nerve, is in reality a system 

 of nervous arrangement adapted particularly for the 

 performance of the functions of organic life. It consists 

 of a series of ganglia united by intermediate branches, 

 and distributes its regular branches in the three great 

 splanchnic cavities those of the head, chest, and abdo- 

 men. In the trunk it lies mainly on the side of the spine 

 (the student should carefully study the illustration, Fig. 

 1 14, in order to become familiar with this important nerve) 

 and communicates with all the spinal and several of the 

 cranial nerves. 



The sympathetic nerve serves to maintain vitality in 

 all the important portions of the system. It exerts a 

 controlling influence over the involuntary functions of 

 digestion, absorption, secretion, circulation, and nutrition. 

 Every portion of the body is, to a certain extent, under its 

 influence, as filaments from this system of nerves accom- 

 pany the blood-vessels throughout their course. 



An important function of the sympathetic system is to 

 form a communication of one part of the system with 

 another, so that when one organ is affected, every other 

 organ will act accordingly. If, for example, disease 

 seizes the brain, the stomach, by its sympathetic connec- 

 tion, becomes aware of it; and since nourishment would 

 augment the disease, the stomach refuses to receive food, 

 and perhaps throws off what has already been taken. The 

 loss of appetite in certain diseases is thus a kind provision 

 of nature that prevents our taking food when it would be 

 injurious; following this intimation, we, as a general rule, 

 should abstain from food until the appetite returns. 



