CHAPTER XXIV 

 SYMPATHETIC SYSTEM SLEEP 



Cranial ganglia Cervical ganglia Thoracic ganglia Ganglia in the abdominal and the 

 pelvic cavities General properties of the sympathetic ganglia and nerves Direct 

 experiments on the sympathetic Vasomotor centres and nerves Reflex vasomotor 

 phenomena Vaso-inhibitory nerves Trophic centres and nerves Sleep Dreams 

 Condition of the brain and nervous system during sleep. 



LIKE the cerebro-spinal system, the sympathetic is composed of 

 centres, or ganglia, and nerves. The ganglia contain nerve-cells, most 

 of which differ but little from the cells of the encephalon and spinal 

 cord. The nerves are composed of fibres, some of which are nearly 

 identical in structure with the ordinary motor and sensory fibres, while 

 many are the so-called gelatinous fibres. The nerve-fibres are con- 

 nected with the cells in the ganglia, and the ganglia are connected with 

 each other by commissural fibres. 



The sympathetic ganglia constitute a continuous chain on either 

 side of the body, beginning above with the ophthalmic ganglia and ter- 

 minating below in the ganglion impar. It is important to note, how- 

 ever, that the chain of ganglia is not independent, but that each ganglion 

 receives motor and sensory filaments from the cerebro-spinal nerves, and 

 that filaments pass from the sympathetic to the cerebro-spinal system. 

 The general distribution of the sympathetic filaments is to mucous mem- 

 branes and possibly to integument, to the heart, to non-striated 

 muscular fibres, and particularly to the muscular coat of the arteries. 

 So far as has been shown by anatomical investigations, there are no 

 fibres derived exclusively from the sympathetic that are distributed to 

 striated muscles except those which pass to the muscular tissue of the 

 heart. Near the terminal filaments of the sympathetic, in most of the 

 parts to which these fibres are distributed, there exist large numbers of 

 ganglionic cells. 



The general arrangement of the sympathetic ganglia and the distri- 

 bution of the nerves may be stated very briefly ; but a knowledge of 

 certain anatomical points is indispensable as an introduction to an intel- 

 ligent study of the physiology of this system. 



In the cranium, are the four cranial ganglia the ophthalmic, the 

 spheno-palatine, the otic and the submaxillary. In the neck, are the 



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