CH. XXI.] 



VASO-MOTOR NERVES' 



299 



The vaso-constrictoi' nerves for the whole body leave the spinal 

 cord by the anterior roots of the spinal nerves from the second 

 thoracic to the second lumbar both inclusive. They leave the 

 roots by the white rami communicantes and pass into the ganglia 

 of the sympathetic chain which lies on each side along the front 

 of the vertebral column. The ganglia on this chain (the lateral 



Fig. 284. Transverse section through half the spinal cord, showing the ganglia. A, ante- 

 rior cornual cells ; B, axis-cylinder process of one of these going to posterior root ; 

 C, anterior (motor) root : 1), posterior (sensory) root; E, spinal ganglion on posterior 

 root; F, sympathetic ganglion; O. minus communicans ; II. posterior branch of spinal 

 nerve : I, anterior branch of spinal nerve ; a. long collaterals from posterior root fibres 

 reaching to anterior horn ; fc, short collaterals passing to Clarke's column ; <, cell in 

 Clarke's column sending an axis-cylinder (rf) process to the direct cerebellar tract ; 

 f, fibre of the anterior root ; /, axis-cylinder from sympathetic ganglion cell, dividing 

 into two branches, one to the periphery, the other towards the cord : a, fibre of the 

 anterior root terminating by an arborisation in the sympathetic ganglion ; h, sympa- 

 thetic fibre passing to periphery. (Ramon y Cajal.) 



ganglia of Gaskell) may also be called the chain of vaso-motor 

 ganglia, because here are situated cell stations on the course of 

 the vaso-constrictor nerves for the head, trunk and limbs. That is 

 to say, the small medullated nerve-fibres terminate by arborising 

 around the cells of these ganglia, and a fresh relay of axis-cylinder 

 processes from these cells carry on the impulses. 



The preceding figure represents diagrammatically how this 

 occurs. The sheaths of the fibres are not represented. 



