526 



PHYSIOLOGY 



Motor and inhibitory fibres to uterus and vagina. 



(5) The fore limb receives nerves from the white rami of the 

 fourth to the tenth thoracic nerves. All these fibres are connected 

 with cells in the stellate ganglion. They convey : 



Vaso-constrictor impulses to the blood-vessels. 

 Secretory nerves to the sweat glands. 



(6) The hind limb is supplied by the nerve-roots from the eleventh 

 thoracic to the third lumbar inclusive. The cell stations of these 



to 



r IT 



j ----- Spinal cord 



6-/1) Sympathetic chain 



X/Kj- Solar ganglion 



A. B. 



FIG. 238. Figure (after LANGLEY) to show the probable mode of con- 

 nection of the fibres of the splanchnic nerve with nerve-cells. 



A, usual type, all the fibres passing through the lateral chain 

 to end in the collateral ganglia of the solar plexus ; B, alternative 

 condition, in which a small minority of the fibres have their cell- 

 stations in the sympathetic chain. The pre-ganglionic fibres are 

 black, the post-ganglionic red. 



fibres are situated in the sixth and seventh lumbar and first sacral 

 ganglia. They convey : 



Vaso-constrictor impulses. 



Secretory nerves to the sweat glands. 



Every fibre of the sympathetic system is thus in some point of 

 its course interrupted by a nerve-cell, and Langley has shown that 

 this is the only cell-break in the fibre, i.e. every fibre is connected 

 with one cell and one cell only. This law applies not only to the 

 sympathetic fibres but also to the fibres of the other visceral nerves. 

 Each fibre therefore can be regarded as made up of two sections 

 a pre-ganglionic fibre arising in the central nervous system and passing 

 down to a ganglion as a fine medullated nerve fibre, and a post- 



