There are several: to name the main ones it would be: quadratus femoris, gemellus superior, gemellus inferior, obturator internus, obturator extenus.
Piriformis
intercostals
synergist
A synergist muscle is a muscle that aids another by promoting the same movement.
The gastrocnemius is a synergist of the soleus.
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Some of the synergist muscles in the human body are the masseter, temporalis, supraspinatus, and the extensor digitorum. Examples if the antagonist muscles are the flexor digitorum superficial is, triceps brachii, extensor carpi radials longus, and the internal intercostals.
They are :bicsps, brachii,thoracis, dorsi, andmajor
iliacus,psoas major adductor longus ,piriformis
infraspinatus and teres minor
Synergists as well as fixator muscles.
The agonist being the biceps brachii group. The two synergist muscles that assist the biceps brachiiare the brachialis and to a lesser extent the brachioradialis.