NEUKO-MUSCULAE MECHANISM 



145 



mechanism (JV. vi.), the other passing down the spinal cord 

 to send collaterals to the cells in the grey matter. (2) The 



FIG. 72. Connections of Cochlea with Central Nervous System. Coch.R., 

 cochlear root of eighth nerve ; N.Acc., tuberculum acusticum and nucleus 

 accessorius sending fihres to the cerebrum (CB.) and to the oculo-motor 

 mechanism (N. vi.) ; CBL., cerebellum. 



descending branch forms connections with the medullary 

 nuclei as it passes down. 



6. The Auditory Centre and the Physiology of Hearing 



The qualities of sound which can be distinguished by the 

 sense of hearing are loudness amplitude of vibration ; pitch 

 rate of vibration; and quality the character of the sound 

 given by the over-tones. The perception of this last is 

 essentially a perception of pitch. 



Loudness. It is easy to understand how the peripheral 

 neurons in the internal ear are more powerfully stimulated 



10 



