Anatomy of spinal anesthesia: some old and new findings.


Anatomy is the oldest of medical sciences, and it might be assumed that the structures relevant to spinal anesthesia were well described prior to the inception of drug administration into the cerebrospinal fluid (CSF). Meticulous descriptions of spinal anatomy from the 19th and early 20th centuries set the stage for clinical techniques. (Reading these old papers demonstrates that important original observations may fail to become incorporated into modern texts.) But the spinal canal and subarachnoid space present special challenges to the anatomist. The contents of the canal are frail or fluid, and formidable bony and ligamentous barriers preclude easy exposure. Also, preservation by desiccation or embalming alters the consistency of tissues, and death disrupts the balance of pressures in the CSF and vessels that hold the spinal contents in position. Inevitably, what is revealed by dissection, even in a living subject, does not represent a natural state. Mthough in vivo investigation using modern imaging methods has filled many of the gaps such that a fairly complete schema can be assembled from old and new sources, some limitations do persist. Our ability to accurately identify the vertebral level of needle insertion by examination of the back is fairly modest, despite reassuring instruction that the line between the iliac crests provides a reliable landmark. This reference line may cross the vertebral column as high as the L3-L4 disc or as low as the LS-S1 disc (1-3). Unaided by radiologic imaging, the accuracy of predicting the level of needle insertion is about 50% at best (4-6). Anomalous patterns of vertebral segmentation (7) further limit our clinical ability to determine the level of punc-

Cite this paper

@article{Hogan1998AnatomyOS, title={Anatomy of spinal anesthesia: some old and new findings.}, author={Quinn H. Hogan}, journal={Regional anesthesia and pain medicine}, year={1998}, volume={23 4}, pages={340-3; discussion 384-7} }