490 GENEKAL ANATOMY. 



unite in theintervertebral foramen, where the posterior presents 

 a swelling or ganglion, with which the anterior is simply in 

 close contact. This last does not concur in forming this gan- 

 glion, as is said in the greater part of the treatises on anatomy, 

 although this peculiarity was pointed out long ago by Haase, 

 Munro, and Scarpa, to whom even the discovery has been at- 

 tributed. Gall only remarks, that at the neck the anterior 

 roots of the spinal nerves are soft, pulpy, and reddish; which 

 has deceived the anatomists who have examined this region. 

 In the cranium the nerves present no such distinct roots. At 

 the place where the nerves detach themselves from the me- 

 dulla oblongata, the neurilema abandons them or becomes soft- 

 ened, and confounded with the pia mater, and the medullary 

 substance alone is continuous with that of the encephalon. 

 The interior filaments of the nerve are sooner abandoned by 

 the neurilema than the exterior filaments: it follows, that where 

 the nerve is torn, it breaks farther outwards than inwards, and 

 there remains a prominence which has been erroneously com- 

 pared to an apophysis upon which the nerve is implanted. 



774. In their course, the nerves branch, preserving near- 

 ly the same size in the interval of their divisions. These last 

 consist only in a separation of the component filaments, and 

 do not resemble those of vessels. The divisions of the nerves 

 are in general accompanied by those of the vessels, although 

 they do not always exactly correspond. The nerves commu- 

 nicate with each other in three different manners: 1st, by anas- 

 tomoses; 2d, by plexus; 3*d, by ganglions. 



775. By anastomosis is understood the uniting of two 

 nerves. This union was thus named by the ancients, because 

 they regarded the nerves as vessels in which the nervous fluid 

 circulated, and compared them, in this respect, to arteries. 

 This expression, which has been criticized, is convenient 

 enough; for there is not, in anastomoses, a simple application 

 of the nervous filaments, but a true communication of these 

 filaments, a junction of their canal, which in truth contains a 

 substance which remains there, and not a circulating fluid, as 

 was supposed formerly. The anastomoses take place some- 

 times between the branches of the same nerve, sometimes be- 



