582 CIRCULATION OF BLOOD AND LYMPH. 



chorda tympani branch of the seventh nerve; the preganglionic 

 fibers terminate probably in the small peripheral ganglia connected 

 with these glands. The fibers that emerge in the ninth pass in 

 part directly to the tongue and in part terminate first in the otic 

 ganglion, whence they are distributed with the branches of the 

 inferior maxillary to the lower lips, cheeks, gums, and parotid and 

 orbital glands. Dastre and Morat describe the vasodilators in the 

 cervical sympathetic as reaching the fifth cranial nerve by com- 

 municating branches from the superior cervical ganglion and state 

 that they cause dilatation of the bucco-facial region, that is, 

 the lips, the gums, cheeks, palate, nasal mucous membrane, and 

 the corresponding skin areas. 



The Trunk and the Limbs. The vasoconstrictor fibers for 

 these regions are distributed, so far as is known, chiefly to the skin. 

 They are all derived immediately from the sympathetic chain and 

 ultimately from the outflow in the anterior roots of the thoracic 

 and lumbar spinal nerves. Those for the upper limbs arise from 

 the midthoracic region chiefly (fourth to ninth thoracic nerves), 

 those for the lower limbs arise in the nerves of the lower thoracic 

 and upper lumbar region (eleventh, twelfth, thirteenth thoracic 

 [dog] and first and second lumbar). The vasodilator fibers in the 

 nerves of the limbs have been demonstrated frequently, as already 

 explained. Whether or not these fibers also pass through the 

 sympathetic system, following the same general course as the 

 vaso constrictors, has not been shown conclusively. The most 

 definite work at present (Bayliss) indicates that the vasodilator 

 effect is directly caused in some unknown way by fibers found 

 in the posterior roots of the nerves forming the brachial and the 

 sciatic plexus. The unsatisfactory explanations offered for this 

 result have been referred to (p. 568). 



The Abdominal Organs. The stomach and intestines receive 

 their most important supply of vasoconstrictor fibers by way of the 

 splanchnic nerves and celiac ganglion. These fibers emerge from 

 the cord in the lower thoracic spinal nerves, from the fifth down, 

 and the upper lumbar nerves, and they supply the whole mesenteric 

 circulation as far as the descending colon. According to some 

 observers (Frangois-Franck and Hallion), the mesenteric vessels 

 receive a supply of vasodilator fibers by the same general route, and 

 it is also stated that similar fibers reach this region through the vagus 

 nerve. Concerning this latter statement at least further con- 

 firmation is necessary. The pancreas has been shown to receive 

 vasoconstrictor fibers by way of the splanchnics, and the kidney, 

 according to Bradford, receives vasodilator as well as vasocor^ 

 stricter fibers from the same nerve. Most of the vasomotor fibers to 

 the kidney of the dog emerge from the cord in the roots of the 



