Question

An antagonist is a muscle that _____.a. sablizes a joint,b. directly performs a specific movement, c.contracts at the time as other muscles. contracts in direct opposition to another muscle

Answer 1

Antagonist muscles contracts in direct opposition to another muscle(agonist). Antagonistic muscles are the muscles that create an opposing joint force to the agonist muscles by providing resistance to prevent overrun. The muscles of antagonists and agonists often occur in pairs, called antagonistic pairs. Agonists and antagonists are located on opposite sides of joint. When one muscle contracts, the other relaxes. For example the tricep muscle is the antagonist during the elbow flexion where the bicep is the agonist. While the agonist contracts to cause the movement, the antagonist usually relaxes to prevent the agonist.

  However, the antagonist does not always relax, another function of the antagonist muscles may be to slow down or stop movement. We can see this if the weight in the bicep curl was very heavy, while the weight is lowered from the top position, the antagonist tricep muscle would produce enough tension to help control the movement as weight decreases.

The tricep becomes the agonist and the bicep becomes the antagonist when the elbow extends against gravity while doing a push up, a bench press or a tricep pushdown.