Define the term synergist in muscle actions.

The term synergist refers to a muscle that assists the prime mover, also known as the agonist, in performing a particular action during movement. Synergists help enhance the effectiveness of the prime mover by providing additional force or by stabilizing joints involved in the motion, which can lead to more efficient and coordinated movements. For instance, when performing a bicep curl, the biceps brachii is the prime mover, while muscles such as the brachialis and brachioradialis act as synergists to assist in the flexion of the elbow. This cooperation among muscles ensures that the movement is smooth and controlled, showcasing the important role synergist muscles play in functional anatomy and overall movement dynamics.