106 PHYSIOLOGY FOR NURSES 



of vision and hearing, but the use of all muscles in- 

 volved in uttering articulate sounds, moving the eye- 

 balls in unison or the hand in Avriting, and the centers 

 for each must not only be associated with each other, 

 but each in turn must be closely connected with those cen- 

 ters which originate the thought to be expressed, select 

 words with the proper shade of meaning, or comprehend 

 the full meaning of a writer or speaker; while the sen- 

 sory nerves of lips and tongue must also be in harmony. 

 The area involved, therefore, would be large segments 

 of the frontal, parietal, occipital and temporosphenoidal 

 lobes. Probably, too, special sections are devoted to 

 musical sense, associated with language, at least in vo- 

 cal music, since we find some children devoid of all ideas 

 of music while others, at an equally early age, have what 

 wo call a "good ear" for musical sounds. 



THE CRURA, PONS, CEREBELLUM, MEDULLA 



Our knowledge of the remaining segments of the 

 brain is neither so extensive nor so definite as that which 

 we possess of the cerebrum. 



The crura cerebri are in the main composed of white 

 fibers which convey nerve impulses to and from the cor- 

 tex through the pons to the medulla, and thence to the 

 spinal cord; though they contain gray matter supposed 

 to be concerned in coordinating the movements of the 

 eyeball and iris. 



The pons consists, superficially, of transverse fibers 

 which connect the hemispheres of the cerebellum with 

 each other and deeply of longitudinal fibers, derived 

 from the crura, running to the medulla. It may assist 

 in regulating automatic voluntary movements (Flint). 



The corpora striata and optic thalami are masses of 



