MEMBRANES OF THE SPINAL CORD. 



3 2 9 



presents two serous surfaces. Internally, bands of nbro-elastic 

 tissue attach it to the pia mater along the posterior median line 

 of the cord and form the subarachnoid septum (Fig. 97). The 

 external spinal veins and a considerable space separate the arach- 

 noid from the pia mater. That subarachnoid space is filled with 

 fluid. By the ligamenta denticulata it is divided into the anterior 

 and posterior subarachnoid spaces, which, through the foramen 

 magnum, are continuous with the same spaces in the cranial 

 cavity (Figs. 97 and 6). 



Pia Mater. The pia of the cord (pia mater spinalis] is much 

 stronger than that of the brain (Figs. 97 and 98). It has two 



Ligamentum denticulatum 



Interverte- 

 bral foramen 



Body of 



vertebra 



Periosteum 



Dura mater 



Subdural 



space 



Arachnoid 



Subarachnoid 



space 



Pia mater 



Fig. 98.- 



-Diagrammatic section of the spinal meninges and spinal cord. 

 (After Morris's Anatomy.} 



distinct layers, the inner of which is continuous with the brain 

 pia and forms an epineurium for the cord and roots of the spinal 

 nerves. The outer is the more vascular layer. Both layers dip 

 into the anterior median fissure; they form the anterior septum 

 which contains the anterior spinal artery. The inner layer is 

 attached to the septum in the posterior median fissure. The outer 

 layer forms the linea splendens along the front of the cord, and the 



