THE DISSECTION OF THE BACK 



L.V. 



Conus 

 medullaris 



termed respectively the intumescentia cervicalis and intumescentia 

 lumbalis. The cervical enlargement, which is connected with 

 the nerves of the superior extremities, is the more evident of 

 the two. It begins at the upper end of the medulla spinalis 

 (O.T. spinal cord), attains its greatest breadth (13 or 

 14 mm.) opposite 

 the fifth or sixth 

 cervical vertebra, 

 and subsides op- 

 posite the second 

 thoracic vertebra. 

 The lumbar en- 

 largement is con- 

 nected with the 

 nerves of the in- 

 ferior extremities. 

 It begins at the 

 level of the tenth 

 thoracic vertebra, 

 attains its maxi- 

 mum transverse 

 diameter (n to 

 13 mm.) opposite 

 the last thoracic 

 vertebra, then it 

 rapidly tapers 

 into the conus 

 medullaris. 



Filum Termin- 

 ate. The deli- 

 cate thread - like 

 terminal filament 

 lies amidst the 

 numerous long 

 nerve-roots which 

 occupy the lower part of the vertebral canal, but it can 

 readily be distinguished from them (i) by its silvery glisten- 

 ing appearance, and (2) by its continuity with the extremity 

 of the conus medullaris (Fig. 23). 



It is composed chiefly of pia mater, although the central 

 canal of the medulla spinalis is prolonged down in its interior 

 for nearly half its length, and nervous elements can be traced 



s.v. 



Coccyx 



FIG. 23. Sagittal section through the lower part 

 of the Vertebral Canal. 



