Comprehensive Osteopathic Medical Licensing Examination (COMLEX USA) Practice

Which muscle strength grade is absent of any muscle contraction?

1. Muscle strength grade 0

2. Muscle strength grade 1

3. Muscle strength grade 2

4. Muscle strength grade 3

The correct answer is: Muscle strength grade 0

Muscle strength grade 0 signifies that there is no detectable muscle contraction. This level of strength is characterized by the complete inability of the muscle to exert any force, even when assessed manually or observed for any involuntary contractions. It indicates a total absence of muscle activity in the specific muscle or muscle group being evaluated. In contrast, muscle strength grade 1 indicates that there is a flicker of muscle contraction, but it is not strong enough to produce any movement against gravity. Grade 2 denotes that the muscle can move through a full range of motion, but only when gravity is eliminated (like in a horizontal plane). Grade 3 refers to muscle strength that allows movement against gravity but requires that the motion be performed with minimal resistance. Thus, the definition of muscle strength grade 0 as absent of any muscle contraction clearly distinguishes it from other grades where some degree of muscle activity or movement is present.