The space surrounding the spinal cord within the spinal canal where a local anesthetic may be injected is called the:

• A. Epidural
• B. Subarachnoid
• C. Intrathecal
• D. Subdural

Answer: (A)

In spinal anatomy, the epidural space is the area just outside the dura mater within the vertebral canal. It contains fat and veins and is the space where a local anesthetic can be injected to block the nerve roots as they exit the spinal cord, producing regional anesthesia without entering the CSF. The subarachnoid space, by contrast, lies between the arachnoid and pia mater and contains cerebrospinal fluid; injections there yield spinal (intrathecal) anesthesia. The subdural space is a potential space between the dura and arachnoid and is not the typical site for standard anesthetic injections. Thus, the described space is the epidural space.