It's an auxiliary muscle. For example, if you are doing squats, your hamstrings are an auxiliary muscle group; they work together with your quads and buttocks, which are the primary muscles being worked.
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Synergists muscles in a bench press are triceps and anterior deltoids. When performing a bench press if an athlete wants to make sure that most of the load will be distributed on his/hers pectoralis major (chest muscles) make sure to contract those muscles before the actual push...otherwise synergists will do big part of the work.
The synergist muscle is a kind of muscle that performs or helps perform the same set of joint motion as the agonists. Synergist muscle acts on movable joints.
Risorius muscle
A synergist muscle is a muscle that aids another by promoting the same movement.
The muscle that aids the jaw in closing is the temporalis muscle. The masseter is the muscle that primarily moves the jaw.
peroneus tertius
Piriformis
infraspinatus muscle
quads- rectus femoris
Gastrocnemius
agonist, antagonist, synergist
Latissimus dorsi is the synergist of the teres major.Specifically, a synergist is a muscle which acts with another. The latissimus dorsi helps adduct and rotate the shoulder to elbow bone called the humerus. The teres major is a shoulder-related muscle.
synergist