i go THE NERVOUS SYSTEM 



between it and the inferior cervical ganglion, produce precisely 

 the same symptoms as in (a), but, in addition, the blood- 

 vessels and sweat glands of a part or parts of the upper limb 

 are affected. 



(c) Lesions occurring at the inferior cervical ganglion^ or 

 between it and the first thoracic ganglion (or the second, as 

 the case may be), cut off the sympathetic supply of the whole 

 of the upper limb and of the head and neck, on the same side. 



(d) Lesions affecting the sympathetic trunk in the thoracic 

 region only involve the particular segment or segments in 

 which they are situated, as each ganglion possesses its own 

 white ramus communicans. They therefore produce no char- 

 acteristic or widespread symptoms. 



(e) In the same way, lesions occurring in the lumbar or 

 sacral part of the sympathetic trunk are definitely limited in 

 their effects to the regions supplied by the ganglia involved. 



In the abdomen, however, the cceliac ganglia and plexus 

 (p. 1 88) may not only be affected by tumours in connexion 

 with the viscera in their neighbourhood, but they themselves 

 may be the site of tuberculous disease. Certain cases of 

 Addison's disease have been recorded in which, at the subse- 

 quent post-mortem examination, such a condition was found 

 to be present, while the supra-renal glands were perfectly 

 normal (p. 408). 



REFERRED PAIN 



The Viscero- sensory Reflex. It has been recognised for 

 many years that painful sensations may be experienced in some 

 area or areas remote from the exciting cause, but it is only 

 recently that the importance of such referred pains has been 

 realised. 



The simplest instances of referred pain are found when 

 stimulation of one sensory branch of a spinal nerve produces 

 painful sensations in the area supplied by another sensory 

 branch of the same nerve. The classical example occurs in 

 tuberculous disease of the hip-joint. In this case the patho- 



