VASOMOTOR SUPPLY OF THE ORGANS. 581 



This fact, therefore, fits exactly the view that is being considered. 

 The peripheral constriction, by raising general blood-pressure, dilates 

 the brain more or less, and, what is more important, drives more 

 blood through it. It is difficult to understand why psychical 

 activity is always associated in this way with a peripheral con- 

 striction unless the object of the reflex is to increase the blood- 

 supply to the brain. Even if vasomotor fibers are subsequently 

 shown to be present in the brain, the importance of this reflex in 

 providing a greater flow to the central organ at the time that it is 

 in activity must still be admitted. A general irrigation, so to speak, 

 is provided for by this means. Local vasomotors may be used to 

 divert this flow mainly through one or another cerebral area. 



Vasomotor Nerves of the Head Region. The vasomotor 

 supply of the various parts of the head, including the mouth cavity, 

 has been investigated by many observers. It would appear from 

 the results of most of these investigations that the vasoconstrictor 

 supply for the skin, including the ears, the eye, the mouth, and 

 buccal glands, is derived mainly, if not entirely, from the sympa- 

 thetic nervous system. These fibers arise from the spinal cord in the 

 upper thoracic nerves, first to the fifth or sixth, emerge by the rami 

 communicantes to the sympathetic chain, in which they pass upward 

 and end, for the most part, in the superior cervical ganglion. From 

 this ganglion they are distributed, by various routes, as postgan- 

 glionic fibers, in one interesting instance the constrictor fibers 

 for the head were supposed to take a somewhat different course. 

 It was shown by Schiff, long ago, that in the rabbit the ear receives 

 vasomotor fibers from the auricularis magnus nerve, a branch of the 

 third cervical nerve. Later investigations indicate (Meltzer) that 

 the ear, in fact, receives most of its vasoconstrictor fibers by this 

 route. Fletcher, however, has shown that these fibers do not emerge 

 from the brain in the roots of the third cervical, but rather in the 

 general outflow from the thoracic region. After reaching the sym- 

 pathetic chain these particular fibers pass to the third cervical by 

 the gray rami from the first thoracic ganglion, which communicate 

 with a number of the cervical nerves. On the other hand, the 

 vasodilator fibers for the head are supplied in part by way of the 

 cervical sympathetic, following the same general path as the con- 

 strictors, and in part by way of the cranial nerves (seventh, ninth) 

 and the sympathetic ganglia with which they connect. According 

 to Langley, the outflow of the seventh nerve passes to the spheno- 

 palatine ganglion, whence as postganglionic fibers they accompany 

 the branches of the superior maxillary nerve and cause vasodila- 

 fation in the membrane of the nose, soft palate, tonsils, uvula, roof 

 of mouth, upper lips, gums, and pharynx. The well-known dilators 

 of the submaxillary and sublingual glands are contained in the 



