Physical Therapy Assistant Practice Exam

What term refers to the overflow or spread from stronger to weaker muscles?

1. Reciprocal inhibition

2. Irradiation

3. Successive induction

4. Rhythmic initiation

The correct answer is: Irradiation

Irradiation is the correct term that describes the spread of neural activity from stronger muscles to weaker muscles. This phenomenon occurs during physical therapy or rehabilitation exercises when the contraction of stronger muscles facilitates the activation of weaker muscles through sensory input and motor pathways. Essentially, when the stronger muscles contract, they generate greater tension and engage the surrounding or synergistic muscles, thereby enhancing their strength and control. This is particularly beneficial in therapeutic settings as it helps improve overall muscle coordination and function. In contrast, the other terms in the options pertain to different concepts in neuromuscular control and therapeutic principles. Reciprocal inhibition involves the relaxation of antagonist muscles when the agonist muscles are activated. Successive induction refers to a sequential form of muscle excitation that occurs after a muscle contracts. Rhythmic initiation is a technique used to improve movement patterns and motor control through rhythmical cues. Each of these concepts plays an important role in physical therapy but describes different mechanisms than irradiating muscle activity.