Intermediate Subarachnoid Space Quiz

Q1. Why is the lumbar subarachnoid space a useful site for lumbar puncture?

• It ends at L1
• It lies outside the dura
• It contains no neural structures
• It provides CSF access below the usual termination of the spinal cord

Q2. At which interspaces is lumbar puncture commonly performed in adults?

• C1-C2
• T1-T2
• L3-L4 or L4-L5
• T6-T7

Q3. How does the subarachnoid space differ from the potential subdural space?

• It is a real CSF-filled space, unlike the normally potential subdural space
• Both lie outside dura
• Both are normally filled with epidural fat
• The subarachnoid space is normally collapsed

Q4. Which pial structures cross the spinal subarachnoid space laterally toward the dura?

• Ligamenta flava
• Denticulate ligaments
• Posterior longitudinal ligaments
• Intervertebral discs

Q5. What is the relationship of spinal nerve roots to the subarachnoid space?

• Proximal spinal nerve roots traverse the subarachnoid space
• Roots remain inside spinal cord gray matter
• All spinal nerve roots lie only in epidural fat
• Roots never contact CSF

Q6. Through which opening is the spinal subarachnoid space continuous with the cranial subarachnoid space?

• Optic canal
• Foramen magnum
• Jugular foramen only
• Foramen ovale

Q7. Why can cauda equina roots move relative to a lumbar puncture needle?

• They are embedded in vertebral bone
• They lie outside the meningeal sac
• They are mobile within CSF in the lumbar cistern
• They are fused to the arachnoid

Q8. What distinguishes an intrathecal injection from an epidural injection?

• Intrathecal injection enters the subarachnoid space
• Both enter the epidural space
• Epidural injection enters the spinal cord
• Intrathecal injection remains outside dura

Q9. How does the subarachnoid space relate to the conus medullaris?

• It becomes the epidural space at L1
• It enters the central canal
• It terminates exactly at the conus
• It continues below the conus as the lumbar cistern

Q10. Which structures are found together in the lumbar subarachnoid space?

• CSF, cauda equina roots, and filum terminale internum
• Spinal cord only
• Lumbar vertebral bodies
• Epidural fat and vertebral venous plexuses only