Final answer:
Elisabeth's doctor would likely prescribe a centrally acting muscle relaxant like cyclobenzaprine to relieve her back muscle spasms by acting on the central nervous system.
Step-by-step explanation:
If Elisabeth is experiencing painful muscle spasms in her back, her doctor might prescribe a centrally acting muscle relaxant. These medications work by acting on the central nervous system to relax muscles. A commonly prescribed medication in this category is cyclobenzaprine, which is known to help relieve muscle spasms without directly affecting muscle function.
Centrally acting muscle relaxants can cause side effects that are similar to those observed in movement disorders of the extrapyramidal system. This is due to their effects on the dopaminergic activity within the basal nuclei, which is an important area of the brain that helps regulate movement and coordination.