<prompt> The subarachnoid space ends atL1L2L5S2  <response>: Arachnoid dural sheath end at the lower end of the S-2 veebra. Subarachnoid space terminates at the caudal lower border S-2 veebra. This is also the ending of the sub-dural space. Ref - BDC 6thedition vol 2 