While doing spinal anesthesia, the drug get deposited between:

In spinal anaesthesia, local anaesthetic solution injected into the subarachnoid space, between pia and arachnoid, blocks conduction of impulses along all nerves with which it comes in contact. Regardless of the anaesthetic agent used, the desired effect is to block the transmission of afferent nerve signals from peripheral nociceptors. Sensory signals from the site are blocked, thereby eliminating pain. The spinal cord usually ends at the level of L2 in adults and L3 in children. Dural puncture above these levels is associated with a slight risk of damaging the spinal cord and is best avoided.