Subarachnoid space 蛛网膜下隙 Position: lies between pia and arachnoid maters containing cerebrospinal fluid Termina| cistern终池:the largest part of subarachnoid space extending from termination of spinal cord to level of s2. where it is occupied by nerves of cauda equina, so it is the best site for a lumbar punctureSubarachnoid space 蛛网膜下隙 ◼ Position: lies between pia and arachnoid maters containing cerebrospinal fluid ◼ Terminal cistern 终池: the largest part of subarachnoid space extending from termination of spinal cord to level of S2, where it is occupied by nerves of cauda equina, so it is the best site for a lumbar puncture