A 19-year-old presents at the emergency department with high fever, severe headache, nausea, and stiff neck for 3 days. The attending physician suspects meningitis and obtains a sample of CSF using a lumbar puncture. From which of the following spaces was the CSF collected?

The subarachnoid space, containing the CSF, is located between the pia and the arachnoid mater. Neither the epidural space, the subdural space, nor the pretracheal space contains CSF. Although the central canal, contained within the substance of the spinal cord, does contain CSF, extraction of CSF from this region would result in spinal cord injury. CSF circulates in the area of the subarachnoid space and can be aspirated only from that location. The subdural space is only a potential space between the dura and arachnoid mater. The epidural space contains the epidural fat and Batson's venous plexus and is the preferred site for aspirating CSF for diagnostic purposes (and epidural anesthesia). CSF is not located in the pretracheal space.