160 THE SPINAL NERVES. 



the inferior go underneath it ; both being adherent to the 

 gangUon as they pass it. Having got by the ganghon, the 

 character of the nerves has been changed ; the sentient have 

 become partly motor ; and the motor partly sentient. There 

 is no longer a nerve of a pure character to be found ; bat 

 each travels hereafter as a sentient and a motar nerve, or 

 one of a mixed nature. Therefore, if we want to look for 

 pure sentient or pure motor nerves, we must seek them near 

 to their origin, from the spinal marrow ; and before they 

 have passed the adjacent ganglion. 



The cervical nerves are seven upon each side ; and are 

 chiefly distributed to the muscles of the neck. 



The phrenic nerve is formed of filaments from the fourth, 

 fifth, sixth, and seventh cervicals ; and from general gan- 

 glionic twigs of communication from the sympathetic : it 

 passes into the chest near the axillary artery ; when, having 

 gained the tendinous portion of the diaphragm, it is spread 

 over the whole substance of that organ. 



The eighteen dorsal pairs are given off by the notches at 

 the extremities of each dorsal vertebra ; in the same manner 

 as the cervical pairs, but these last are less considerable. 

 They furnish the intercostal and dorsal muscles with con- 

 tractility, and with sensation. Besides this the first four 

 are larger than the others, and unite with the last few cer- 

 vical, to supply the fore extremity with nervous energy. 



The lumhar nerves are given ofiT from the loins, in the 

 same manner as the former ; they, however, are larger ; 

 having more to do. They give feeling and motion to the 

 sides of the abdomen ; and it is some of these, together 

 with several of the last dorsal, which are seen dividing the 

 transversalis abdominis into sections ; after having done 

 which, and having pierced the other abdominal muscles, they 

 enter the panniculus and expend themselves upon the skin. 

 They also give strength and sensation to the lumbar mus- 

 cles. They also supply the psoas muscles ; the iliacus 

 muscle ; send off the spermatic nerve ; as well as the crural, 

 which sends twigs to the psoas and iliacus ; to the vasti and 

 rectus ; and a large quantity of filaments to the gracilis ; 

 beside twigs to all the muscles inside of the thigh beyond all 

 this. 



