Reciprocal inhibition serves to?

• A. Decrease Antagonist Opposition to the Action of the Agonist
• B. Increase Antagonist Opposition
• C. Halt Movement
• D. Cause Co-Contraction of Muscles

Answer: (A)

Reciprocal inhibition is the nervous system mechanism that lets a movement happen smoothly by decreasing the activity of the opposing muscle. When an agonist muscle is activated to produce a action, sensory input from that muscle (via spinal pathways) triggers inhibitory signals to the motor neurons of the antagonist. This reduces the antagonist’s force, so there’s less opposition to the movement. For example, when you flex your elbow by contracting the biceps, the triceps are inhibited so they don’t resist the bend.

This isn’t about increasing opposition, halting movement, or keeping both muscles contracting at once. In fact, co-contraction can occur when stabilization is needed, but reciprocal inhibition specifically reduces antagonist activity to enable the intended action.