278 PHYSIOLOGY FOR DENTAL STUDENTS. 



In the thorax, the uppermost ganglion is very large and is 

 called the stellate ganglion. Its postganglionic fibers constitute 

 the vasomotor nerves of the blood vessels of the anterior ex- 

 tremity, and the sympathetic fibers to the heart. Some pregan- 

 glionic fibers run through the stellate ganglion to pass up the 

 neck as the c< rrical xi/)>i/><ifh<tic, their cell station being in the 

 superior cervical ganglion. They act on the pupil (dilating it), 

 on the salivary glands (causing vasconstriction and stimulating 

 glandular changes), and on the blood vessels of the head, face 

 and mucosa of the inside of the mouth. 



From about the fifth dorsal vertebra downwards, ln-anelies run 

 from the sympathetic chain on each side to become collected 

 into a large nerve called the great splanchnic, which passes down 

 by the pillars of the diaphragm into the abdomen and runs to 

 the ganglia of the coeliac plexus. This nerve supplies all of 

 the blood vessels of the intestines and other abdominal viscera. 

 Its action on these vessels has already been described (see p. 

 191). It also carries nerve impulses for the control of the move- 

 ments of the stomach and intestines and for some of the digestive 

 glands. In the abdomen the sympathetic chain gives off branches, 

 which form the pelvic nerves and supply the blood vessels <n' 

 the lower extremity. It is important to note that the connections 

 between the sympathetic system and the cerebrospinal axis are 

 limited to the spinal nerve roots between the second thoracic and 

 the second lumbar. The results which follow stimulation of 

 the sympathetic system are exactly like those which are pro- 

 duced by injections of adrenalin (see p. 130). 



