Final answer:
The herniation has occurred at the L4/L5 or L5/S1 intervertebral discs, causing compression of the spinal nerve. This results in pain and paresthesia in the left leg.
Step-by-step explanation:
The distribution of the pain and paresthesia in the left leg, running down the lateral aspect of the leg and the dorsal surface of the foot, suggests a herniated intervertebral disc. The physician links the distribution of symptoms with nerve L5, which indicates that the herniation has occurred at the L4/L5 or L5/S1 intervertebral discs. This can cause compression of the spinal nerve at the point where it exits through the intervertebral foramen, resulting in pain and/or muscle weakness in the body regions supplied by that nerve.
A herniated intervertebral disc occurs when the nucleus pulposus protrudes through the weakened posterior anulus fibrosus, causing compression of the spinal nerve. In this case, the herniation has occurred at the L4/L5 or L5/S1 intervertebral discs, which are common sites for disc herniation. The resulting symptoms, such as pain and paresthesia running down the lateral aspect of the leg and the dorsal surface of the foot, are consistent with compression of the nerve L5.