Lumbar cistern

The lumbar cistern refers to the subarachnoid space in the lower lumbar spinal canal.

The cistern is an enlargement of the subarachnoid space in the dural sac, distal to the conus medullaris. It contains cerebrospinal fluid and the nerve roots of the cauda equina. As the conus (usually) terminates at the level of the L2 vertebra, the cistern extends from L2 down to S2.

It is the cerebrospinal fluid within the lumbar cistern that is the target of lumbar puncture.