Dictionary > Agonist muscle

Agonist muscle

Definition
noun
A muscle that contracts while another muscle relaxes
Supplement
Muscles may be classified according to the action of a set of muscles. Muscles that work together may be agonist muscles, antagonist muscles, or fixator muscles. Agonist muscles are sets of muscles in which some of them contract while others relax. They produce movements through their own contraction and are responsible for generating specific movements. In contrast, antagonist muscles are those that interfere with the physiological action of another. They eccentrically contract, i.e. slacken to lengthen the muscle so that the action of the agonist at the joint would occur.1 Fixator muscles are those that serve as stabilizers of a part of the body during the movement of another part. It allows the agonist muscle to work effectively by stabilizing the origin of the agonist muscle.
The agonist is typically the muscle that is the largest, most superficial muscle crossing the joint in motion, and is concentrically contracting or shortening the length of the muscle.1
An example of agonist muscle is the triceps brachii contracting during an elbow extension.
See also:

Reference(s):

1 Goodwin, J. (2012). Touch & Movement: Palpation and Kinesiology for Massage Therapists. NY, US: Cengage Learning, Inc. p.38.


You will also like...

Young plant growing from the soil.
Soils

Nutrients in the soil are essential to the proper growth of a land plant. This tutorial deals with the properties of soi..

Sensory systems
Sensory Systems

A sensory system is a part of the nervous system consisting of sensory receptors that receive stimuli from the internal ..

Cell structure
Cell Structure

A typical eukaryotic cell is comprised of cytoplasm with different organelles, such as nucleus, endoplasmic reticulum, G..

Evolution of Life - Ancient Earth
Evolution of Life – Ancient Earth

Autotrophs flourished, absorbing carbon and light. Soon after, primitive life forms that could assimilate oxygen thrived..

Ecosystem Succession
Ecosystem Succession

If the balance of nature is left untouched, landscapes can change dramatically over time. A previous ecosystem is supers..

Pink Lotus plant on a pond
Freshwater Lentic Communities & Animals

This tutorial looks at some of the communities in freshwater lentic habitats. For instance, symbiosis occurs in a commun..