Agonist (muscle)
Encyclopedia
Agonist is a classification used to describe a muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

 that causes specific movement or possibly several movements to occur through the process of its own contraction. This is typically a term designated for skeletal muscles. Agonists are also referred to, interchangeably, as "prime movers" since they are the muscles being considered that are primarily responsible for generating a specific movement.

For an agonist to be effective as a mover in the skeletal system it must actually cross one or more structure(s) that can move. This is typically where the muscle crosses a joint by way of a connecting tendon. As the myofibril
Myofibril
A myofibril is a basic unit of a muscle. Muscles are composed of tubular cells called myocytes or myofibers. Myofibers are composed of tubular myofibrils. Myofibrils are composed of long proteins such as actin, myosin, and titin, and other proteins that hold them together...

s of a muscle are excited into action and then contract, they will create tension and pull through the tendon and pulling the lever arm of bone on the opposite side of the joint closer to the muscles origin.

See also

  • Antagonist
    Antagonist (muscle)
    Most muscles work in pairs, and when a muscle works it needs to have an agonist and an antagonist, unless the muscle's natural state is opposite to that which is produced by the muscle, example Sphincter ani externus muscle....

  • Synergist
    Synergist
    A Synergist is a kind of muscle that performs, or helps perform, the same set of joint motion as the agonists. Synergists muscles act on movable joints. Synergists are sometimes called as "neutralizers" because they help cancel out, or neutralize, extra motion from the agonists to make sure that...

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