Chap. 28.] Sympathetic Nerve, &c. 287 



plex manner in which the nerves are united to each 

 other, and to evince the careful provifion which is 

 made to fupply the moil important vifcera from a 

 variety of fources. 



The ninth pair or- lingual, rifes from the inferior 

 part of the corpora pyramidalia, and pafies out through 

 the occipital bone. After they have arrived on the 

 outfide of the cranium, they adhere firmly for fbmc 

 way to the eighth and the intercoftal ; then after fend- 

 ing a branch to communicate with the cervical nerves, 

 they enter the tongue and are loft in its fubftance. 



The tenth pair of the head is by fome anatomifts 

 confidered as the firft of the vertebral. It rifes by 

 ieparate threads from the fide of the fpinal marrow, 

 paiTes out between the os occipitis and firft vertebra 

 of the neck, and after having given branches to the 

 great ganglion of the intercoftal, and fome of the cer- 

 vical nerves, is loft in the adjoining mufcles. 



It has been already mentioned that a branch of the 

 fixth pair of nerves, joined by a twig from the fifth, 

 accompanies the internal carotid artery through its bony 

 channel, and paffing out of the cranium, both united 

 conftitnte the beginning of the great intercoftal or fym- 

 pathetic nerve. As foon as the nerve has got without 

 the cranium, it is connected a little way with the 

 eighth and ninth pairs ; feparating from thefe it forms 

 a large ganglion, into which enter branches -from the 

 tenth of the head and from the firft and fecond pairs 

 of the cervical nerves. Thence running down the 

 neck with the carotid artery, and diftrijbuting nerves 

 to the adjoining mufcles, it forms another ganglion 

 as it is about to enfier the thorax, whence nerv.e? are 

 lent to the trachea and heart ; thofe which go to the 

 heart being united with nerves from the eighth pair. 

 Below the ful?clavian artery the fibres of the intercoftal 



unite 



