THE SPINAL NERVES 



919 



The roots of the lumbar, sacral, and coccygeal nerves run vertically downward 

 their respective exits, and as the medulla spinalis ends near the lower border 





FIG. 798. Distribution of cutaneous nerves. Dorsal aspect. 



of the first lumbar vertebra it follows that the length of the successive roots must 

 rapidly increase. As already mentioned (page 750), the term cauda equina is applied 

 to this collection of nerve roots. 



