484 NERVES OF THE BRAIN. 



from that in which they were arranged before the nerve entered 

 the ganglion. 



It ousht to be observed, that the combination of nervous 

 fibrillae, so as to bring together those fibrils which originally 

 belonged to different cords, seems to have been kept in view 

 throughout the whole arrangement of the nervous system. It 

 is not only in the plexus and the ganglion that this appears, 

 but, also, in some of the larger nerves ; for in them the fibres 

 which form the cords that compose the nerve, instead of run- 

 ning parallel to each other, along the whole extent of the 

 nerve, form a species of plexus in their course, separating 

 from the fibres with which they were originally combined, 

 and uniting with the fibres of other cords ; as in other cases of 

 plexus.* 



There have been doubts respecting the possibility of a repro- 

 duction of the substance of the nerves when it has been de- 

 stroyed ; but it appears to have been clearly proved by the 

 experiments of Mr. Haighton and others, that a reproduction 

 does really take place so as to continue on the transmission of 

 the nervous fluid .f 



Nine pair of nerves proceed from the brain through the fora- 

 mina of the cranium. They are called Nerves of the Brain, 

 or Cerebral Nerves. One pair passes off between the cranium 

 and the spine, which is called Sub- Occipital. Twenty-nine 

 or thirty pair pass through the foramina of the spine : they are 

 denominated Cervical, Dorsal, Lumbar, and Sacral, from the 

 bones with which they are respectively connected. There are 

 seven pair of cervical nerves, twelve dorsal, five lumbar, and 

 five or six sacral — amounting, with the nerves of the brain, to 

 thirty-nine or forty pair. 



Nerves of the Brain. 



The nerves which go off from the brain and medulla oblon- 

 gata are named numerically, according to the order in which 

 they occur, beginning with the anterior. They also have other 



* See Monro's Observations on the Structure and Functions of the Nervous 

 System. Plate xviii. 

 t See London Philosophical Transactions, for 1795, Part I. 



