306 



PRACTICAL ANATOMY. 



three fissures, the antero-lateral, postero-lateral, and 

 posterior. 



The antero-lateral fissure is the line of emergence of 

 the filaments of the anterior roots of spinal nerves. It is 

 just external to the anterior cornu of the gray matter of the 

 cord. The postero-lateral fissure, a slight groove, gives 

 origin to the posterior roots of spinal nerves. The ex- 

 tremity of the posterior cornu of gray matter extends 

 quite up to the postero-lateral groove. The posterior 



L 



^4 L 



P t P P 



FIG. 137. TRANSVERSE SECTION OF THE SPINAL CORD. 



p, posterior horns ; a, anterior horns ; PR, posterior roots : AR, anterior roots ; A, the 

 white anterior, LL, the lateral, PP, the posterior columns. 



fissure separates the posterior median and the posterior 

 columns of the cord. It is a faintly marked groove, 

 deeper in the cervical than in any other region. The 

 anterior column is a tract of white fibres continuous with 

 the anterior pyramid of the medulla. The lateral col- 

 umn, between the two lateral fissures, is the largest 

 column of the cord. It is a tract of white fibres con- 

 tinuous with the lateral tract of the medulla. The 

 posterior column is a tract of white fibres between the 



