GENERAL SOMATIC SYSTEMS OF CONDUCTION PATHS 175 



combination of symptoms could not be produced by any injury 

 to the nerve-roots or peripheral branches. 



Proprioceptive Systems. Referring back to p. 137, we are 

 reminded that the ascending proprioceptive fibers of the spinal 

 cord effect three types of connections within the brain: (1) in 



Fig. 82. The sensory loss resulting from an injury to the lower part of 

 the spinal cord. The shaded area represents the parts insensitive to cuta- 

 neous painful stimuli and also to the pain of excessive pressure; yet over this 

 area light touch and the tactile element of pressure were appreciated. 

 (After Head and Thompson.) 



the cerebellum; (2) in the brain stem; (3) in the cerebral cortex. 

 The connections of the second and third types are made through 

 the dorsal funiculus and medial lemniscus; they are shown in 



2. Peripheral neuron of pain or temperature. 



3. Peripheral neuron of touch and pressure. 



4. Peripheral motor neurons of spinal nerve. 



5. Peripheral cutaneous neuron of trigeminal nerve. 



6. Secondary neuron of touch and pressure in spinal lemniscus. 



7. Secondary neuron of pain or temperature in spinal lemniscus. 



8. Secondary neuron from lower part of spinal V nucleus entering the 

 spinal lemniscus. 



9. Secondary neuron from chief sensory V nucleus entering the trigemi- 

 nal lemniscus. 



10. Intrinsic correlation neuron of thalamus for thalamic reflexes. 



11, 12, 13. Thalamo-cortical radiations to the postcentral gyrus. 



