Final answer:
The anatomical association linked to failed spinal anesthesia is typically related to issues with the epidural space.
Step-by-step explanation:
When it comes to spinal anesthesia, the anatomical association linked to its failure is most often related to the epidural space.
Spinal anesthesia involves injection into the epidural space surrounding the dural sac, which encapsulates the spinal cord and cerebrospinal fluid. If the needle is not properly inserted into the epidural space or if the space is compromised for some reason, the delivery of the anesthetic may not be successful, leading to a failed spinal anesthesia. Conditions such as a herniated intervertebral disc, which can compress spinal nerves leading to pain and muscle weakness, may indirectly affect the administration of spinal anesthesia by altering the anatomy of the epidural space. However, the direct cause of failed spinal anesthesia is typically an issue with accessing or injecting into the epidural space, not the intervertebral discs, spinal nerves, or the dural sac itself.