The pronator teres muscle is a large, two-headed muscle located in the forearm. It originates at the medial epicondyle of the humerus (upper arm bone) and the coronoid process of the ulna (forearm bone), and inserts into the middle of the radius (forearm bone). The pronator teres muscle is located superficial to the pronator quadratus muscle, and is one of several muscles that make up the posterior compartment of the forearm.

The main function of the pronator teres muscle is to pronate (rotate downwards) the hand and wrist. This movement allows the palm of the hand to face downwards, and is essential for activities such as turning a doorknob or holding a pencil. The pronator teres muscle also helps to flex the elbow joint, bringing the hand closer to the body.

In everyday life, the pronator teres muscle is used in many activities that involve gripping or holding objects, such as opening a jar, turning a doorknob, or writing with a pen or pencil. It is also used in activities that require flexion of the elbow, such as carrying a bag or lifting a heavy object.