THE AUTONOMIC NERVOUS SYSTEM 



749 



is apparently self-governing and independent of cerebral control. 

 The system comprises the sympathetic nerves and their associated 

 ganglia, the sympathetic nervous system, and certain cranial and sacral 

 nerves and ganglia, the cranial and sacral autonomic systems. The 

 fibres are both efferent and afferent. 



The Sympathetic Nervous System. The ganglia connected with 

 this system form a well-marked chain, the lateral chain, lying on either 

 side of the vertebral column, and extending from the neck to the 

 coccygeal region. In addition there are accessory ganglia (collateral 



FIG. 458. DIAGRAM OF THE ARRANGEMENT OF FIBRES IN A MIXED SPINAL NEBVE. 

 (From Purves Stewart's "Diagnosis of Nervous Diseases.") 



ganglia), lying in the abdomen in close connection with the aorta and 

 the large branches arising from it the semilimar or solar, the 

 superior mesenteric and inferior mesenteric ganglia. 



These ganglia are connected with the spinal cord by means of small 

 efferent medullated fibres (the white rami) which pass out by the 

 anterior roots. Each fibre ends by arborizing round the cells of a 

 ganglion. These are the preganglionic fibres. From the cells of the 

 ganglia arise the terminal fibres which go to the various effector organs, 

 smooth muscle, cardiac muscle, or glands. These are known as the 



