Which mechanism increases excitability to target muscles and can restore dysfunctional muscle action?

• A. Irradiation
• B. Facilitation
• C. Inhibition
• D. Reciprocal inhibition

Answer: (A)

Irradiation is about the spillover of neural activation. When a strong muscle group is activated, the excitation can spread to nearby muscles through shared neural pathways, increasing the excitability of motor neurons that innervate the target muscles. This overflow helps recruit and help restore function in weak or dysfunctional muscles by priming them to respond more readily. In rehabilitation, this mechanism explains why resisted or patterned movements in one muscle group can facilitate activation in the corresponding target muscles. The others don’t describe this spreading of activation: general facilitation is broader and not specifically about overflow to the target, inhibition reduces activity, and reciprocal inhibition mainly involves stopping antagonists during agonist contraction rather than boosting the target muscles through overflow.