102 PHYSIOLOGY FOE NURSES 



A broad view of the entire nervous system reveals 

 that the brain is the highest development of the system, 

 presiding over the work of the rest, thinking, ordering, 

 and governing through its subsidiaries. Some of its 

 impressions are received directly, and some of its orders 

 given, through the medium of the cranial nerves; but 

 from the larger portion of the body its various ssnsa- 

 tions and actions must be transmitted to the brain 

 through the spinal cord. In this transmission the cord, 

 like a good subordinate officer, finds many things of 

 such simple and routine nature that the conscious brain 

 need not be troubled with them and itself interprets the 

 information and gives the necessary instructions. Thus 

 it appears that while much of the tissue of the cord is 

 solely employed in conducting impulses to or from the 

 periphery of the body, it is capable of action, not ab- 

 solutely independent, but under general orders of the 

 brain. 



The sympathetic, or more properly autonomic system 

 is much more independent. While connected with the 

 brain and spinal cord, its functions are, in large meas- 

 ure, performed without the conscious will of either. 



The Cerebral Hemispheres. In these subdivisions of 

 the fore brain we find the higher centers. Here reside 

 those intellectual functions which we are thinking of 

 when we say "we 'think." In that part of the cortical 

 matter like bark, surrounding other matter whicli is 

 found over the anterior part of the frontal lobe probably 

 originate the highest philosophic conceptions; in front 

 of the central sulcus (fissure of Rolando) lies the long 

 area stretching from the top to near the bottom of the 

 brain which presides over all motor activity, with the 

 special centers for the lower extremity at the top, those 

 for the upper extremity in the middle and for the face 



