4f PROCEEDINGS OF THE ANATOMICAL ANP ANTHROPOLOGICAL 



SOME POINTS IN THE ANATOMY OF 

 LUMBAR PUNCTURE. 



The operation of puncture of the lumbar subarachnoid space with with- 

 drawal of more or less of the cerebro-spinal fluid for curative and diagnostic 

 purposes was suggested by Quincke in 1891, and has within the last ten years 

 assumed greater importance by reason of its relation to Spinal Analgesia or 

 Anaesthesia, as introduced by Corning and Bier. Though this paper deals 

 primarily with lumbar puncture, its bearing on Spinal analgesia is kept in 

 mind throughout, since the anatomical considerations are practically the same. 

 It is generally admitted that the percentage of failures in this apparently 

 simple operation diminishes markedly with improvement in the technique 

 and in the acquaintance of the operator with the anatomy of the parts. 

 Let me first shortly recall a few anatomical facts before giving the results 

 of investigations made on the subjects in the dissecting-room and on a few 

 skeletons. 



The spinal cord and its membranes are carefully protected posteriorly 

 by the bony laminae of the vertebrae, which overlap each other like slates 

 on a roof except in the upper cervical and lumbar regions where intervals 

 are left through which an instrument can penetrate to the cord. The cord 

 itself ends pretty constantly at the lower border of the 1st lumbar vertebra 

 in the adult, so that puncture of the subarachnoid sac in the interval between 

 the 1st and 2nd lumbar vertebrae entails little risk and in the lower spaces 

 no risk of injury to the cord itself. In the infant at birth, the cord may 

 extend as low as the 3rd lumbar vertebrae The nerve roots forming the 

 cauda equina, lying in their water-bath of cerebro-spinal fluid, make way 

 to a certain extent for the entering cannula. In dissecting-room subjects 

 these roots lie in two sets, one against each lateral wall of the sac, and in 

 all probability this arrangement holds good, to a certain degree at least, in 

 the living state. This would explain certain clinical experiences, such as 

 cases of unilateral anaesthesia, or imperfect diffusion of the injected fluid in 

 spinal analgesia, from its being entangled among the nerve roots of one side. 



The cerebro-spinal fluid, in which are suspended the cord and the cauda 

 equina, is contained within the double wall formed by the two wide sheaths, 



