How do muscles work in antagonistic pairs?

1 Answer
Jun 22, 2016

Skeletal muscle movement takes place by  contraction.
 Muscles shorten during contraction,  Muscles can only pull,
 they never push.
 Muscles work in opposition, one set of muscles contract and pull while another set of muscles relax.

Explanation:

Skeletal muscle movement takes place by  contraction.
 Muscles shorten during contraction,  Muscles can only pull,
 they never push.
 Muscles work in opposition, one set of muscles contract and pull while another set of muscles relax.

The muscle set that creates the movement is referred to was the  agonist. While the muscle that relaxes during movement is called the  antagonist.

When the elbow is flexed the bicep shortens and pulls up on the ulna to reduce the angle between the ulna and the humerus.
When this happens the triceps relax to release the tension on the ulna. The biceps are the agonist and the triceps are the antagonist.

In order to extend the elbow the triceps shorten and pull on the ulna increasing the angle of the humerus and the ulna. The biceps relax during this movement. The triceps are now the agonist and biceps are now the antagonist.

enter image source here

Image from SMARTNotebook lecture by @smarterteacher

For every muscle set there is an agonist working in opposition with an antagonist, flexors to extensors, supinators to pronators, adductors to abductors.

enter image source here

Image from SMARTNotebook lecture by @smarterteacher