280 THE NERVOUS SYSTEM 



There remain certain functions which the cord alone 

 cannot perform— willed movements and the psychical 

 appreciation of sensory impressions. It is the f miction 

 of the cord to convey these impulses between the higher 

 centres and the periphery. 



Lesions of the Spinal Cord in Man 



After complete transverse lesions of the dorsal region, when the 

 effects of shock have passed away a flexion reflex gradually develops. 

 This becomes more and more easily elicitablc, until a stage"^ is reached 

 when stimiilation of any point causes strong flexion of both legs 

 and contraction of the abdominal muscles. This is known as the 

 mass -reflex. 



Reflex micturition and defecation are performed, the stimuli 

 being distension of the bladder and rectum respectivelj'. 



Lesions of the dorsal region involving one-half of the cord lead 

 to a condition known as Brown-Sequard Paralysis. It is char- 

 acterised by — 



1. Motor paralysis of the same side. 



2. Slight vaso-motor paralysis of the same side. 



3. Loss of sense of position and of passive movement on the 



same side. 



4. Loss of touch, pain and temperature sensation on the opposite 



side. 



