The primary function of the pronator quadratus is to assist in the pronation of the forearm. It plays a crucial role in the corresponding movement where the palm faces downward. This function is vital in many activities such as turning a doorknob, using a screwdriver, or typing on a keyboard. The muscle works in conjunction with other muscles, such as the pronator teres, to achieve efficient forearm rotation. Its placement at the distal end of the forearm allows it to exert a pulling force that drives the radius over the ulna during pronation, highlighting its importance in the mechanics of the wrist and hand. Through this function, the pronator quadratus contributes to the overall versatility and dexterity of the human hand, enabling precise motions essential for grasping and manipulating objects.