TRIPLE L GROUP ---- LESSON 4 2DAY - AGONISTS AND ANTAGONISTS - Agonist muscles and antagonist muscles refer to muscles that cause or inhibit a movement. - Agonist muscles causes a movement to occur through its own contraction. - For example, the triceps brachii does during the up phase of a push-up (elbow extension). During the down phase of a push-up, the same triceps brachii actively controls elbow flexion while relaxing. - It is still the agonist. While resisting gravity during relaxing, the triceps brachii is still the prime mover, or controller, of the joint action. For both of those movements the elbow flexor muscles are the antagonists. - 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. This term typically describes muscles which are skeletal muscles. Antagonist muscles oppose a specific movement. - This controls a motion, slows it down, and returns a limb to its initial position. Antagonism is not an intrinsic property. It is a role, played depending on the motion. If the motion is reversed, agonist and antagonist swich roles. A flexor muscle is always flexor. But in flexion, it is always agonist and in extension, it is always antagonist. An extensor muscle is agonist in extension and antagonist in flexion. - Agonist-antagonist pairs - Antagonist and agonist muscles often occur in pairs, called antagonistic pairs. As one muscle contracts, the other relaxes. - An example of antagonisic pairs is the Bicep and Tricep as to contract your tricep relaxes while the Bicep contracts to lift your arm. Reverse motions need antagonistic pairs located in opposite sides of a joint or bone, including abductor-adductor pairs and flexor-extensor pairs. - These consist of an extensor muscle, which opens the joint (i.e., increasing the angle between the two bones) and a flexor muscle, which does the opposite to an extensor muscle. - Not all muscles are paired in this way. An example of exception is Sphincter ani externus muscle.
Posted on: Wed, 08 Oct 2014 10:56:03 +0000
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