THE SPINAL MEDULLA 



535 



Note. In arachnoidal meningoceles, whether simple or 

 complicated by myelo-cystoceles, fine strands are frequently 



FIG. 164. Diagram illustrating some of the Congenital Anomalies of the 

 Vertebral Column and Spinal Medulla. 



a. Meningocele. | d. Myelo-cysto-meningocele. 



b. Myelo-meningocele. e. Myelocele, transverse section. 



c. Myelo-cystocele. | f. Myelocele, longitudinal section. 



The dotted line represents the pia mater, the red line the arachnoid, and the heavy 

 black line the dura mater. 



, l>, c and d show the un-united vertebral arches on transverse section. 



In e and f the vertically shaded areas represent the skin. 



In f the central canal of the spinal medulla is seen opening on the surface at the 

 upper and lower limits of the myelocele. 



found in the subarachnoid space, connecting the arachnoid to 



the pia mater. These strands may be not unlike spinal nerves. 



5. A Myelocele is due to an arrest of development at the 



34 & 



