The rheobasic current for denervated muscle is

• A. Galvanic
• B. Faradic
• C. Sine
• D. Static

Answer: (A)

Denervated muscle can no longer rely on nerve impulses to contract, so it responds best to direct, unidirectional current that depolarizes the muscle membrane directly rather than via the nerve. The rheobase is defined as the smallest current that will produce a contraction given an unlimited pulse duration, and for denervated muscle that requires a direct current. This galvanic (direct) current delivers charge steadily to the muscle fibers, enabling electrotonic depolarization and contraction even without an intact nerve.

Faradic and sine currents rely on nerve conduction to elicit a response, which won’t occur when the nerve is severed. Static electricity is not the appropriate modality for this purpose. Hence, the rheobasic current for denervated muscle is galvanic.