The relationship between the pronator quadratus and supinator

All of your forearm muscles are involved in moving your fingers, including the muscles in your palm. But there is one muscle that helps to move a finger more than any other: the pronator quadratus. As its name suggests, this muscle is located near the front of your forearm and can be used to rotate (or pronate) your hand from a palm-down position to a palm-up position.

This post will explain what is required to move your hand from flexion (palm down) to extension (palm upturned), how this movement is achieved by combining two movements into one, and how all of these movements relate and work together. What term best describes the relationship between the pronator quadratus and supinator? The pronator quadratus muscle is a long, thin, sling-shaped muscle that can be found in the front of your forearm. It begins at the acromion process (also known as the shoulder blade), curls beneath the radius bone, and moves down to just below the elbow joint. 

You can identify this muscle by feeling for its long tendons (tendinous origins) that extend from the acromion process. The pronator quadratus forms a sling across your upper arm and helps to move this upper arm from flexion to extension.

The relationship between the pronator quadratus and supinator :

1. Pronator quadratus muscle :

The pronator quadratus is found in the front of your forearm. It originates on the acromion process of the scapula (shoulder blade) and crosses beneath the radius to insert on the medial epicondyle of your elbow joint. When activated, it helps to rotate your forearm from a palm-down position to a palm-up position.

This movement is called pronation and it can be performed as an isolated movement by flexing and extending your forearm at the elbow and wrist joints. The pronator quadratus is usually active during this movement, although it may be co-activated by other forearm muscles. Since the pronator quadratus crosses two joints, it can be described as a multi-joint muscle.

2. Supinator muscle :

The supinator muscle is located on the outside of your forearm and located inferior to the biceps brachii (long head). It originates on the lateral epicondyle of your humerus (upper arm) and inserts onto your radius bone at its lateral side. When activated, it helps to rotate your forearm from a palm-up position to a palm-down position. 

This movement is called supination and it can be performed as an isolated movement by flexing and extending your forearm at the elbow joint. The supinator is usually active during this movement, although it may be co-activated by other forearm muscles. Since the supinator crosses two joints, it can be described as a multi-joint muscle.

3. Rotation of the wrist :

The main function of the wrist joint is to allow you to make finger movements while maintaining a palm-up or palm-down hand position. The wrist joint is an important source of rotation, allowing your forearm and hand to rotate from a palm-down position to a palm-up position.

To perform this movement, you flex and extend your forearm at the elbow joint and move your wrist from flexion (palm down) to extension (palm upturned). This movement is called pronation. You also make a simultaneous movement of the supinator muscle, which helps to raise your forearm from supination (palm up) to pronation (palm down). Since the supinator crosses two joints, it can be described as a multi-joint muscle.

4. Muscles involved in moving your hand :

The pronator quadratus and the supinator are two of the five muscles that move your hand from a palm-up position to a palm-down position. These muscles include: (1) pronator quadratus, (2) flexor digitorum superficialis, (3) flexor digitorum profundus, (4) palmaris longus, and (5) flexor pollicis longus. During this movement, all five of these muscles are activated to raise your forearm from supination (palm up) to pronation (palm down). Since all of these muscles cross two joints, they can be described as multi-joint muscles.

The terms “pronator quadratus” and “supinator” are often used interchangeably, i.e. one may refer to the pronator quadratus as the supinator. However, although the muscles have similar names, they do not exert the same function. The main difference between these two muscles is that the pronator quadratus also helps to rotate your wrist from a palm-down position to a palm-up position. In other words, it is important to remember that these two muscles operate differently and have different roles in hand movements.

5. Movement of the hands :

The pronator quadratus and the supinator are wrist extensors. This means they are responsible for raising your forearm from a palm-up position to a palm-down position. The movement is made by moving your wrist from flexion (palm down) to extension (palm up). 

This movement is called pronation and it can be performed as an isolated movement by flexing and extending your forearm at the elbow joint, or it can be performed simultaneously with supination (palm up) to pronation (palm down). Since pronation and the supinator both cross two joints, they can be described as multi-joint muscles.