Pronator Quadratus: Functional Anatomy Guide

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By Alex
Last updated on

The pronator quadratus is (L. pronus, lying face down ; quadrus, square.) is a rectangular muscle on the front of the forearm that connects between the radius and the ulna.


It is the prime mover in forearm pronation, receiving help from the pronator teres during rapid pronation.

It is also noted for its role in preventing the separation of the ulna and radius when force is transferred up the forearm through the heel of the palm (e.g. breaking a fall; palm heel strike to a hard surface).

Classified as part of the deep anterior compartment of the forearm, the pronator quadratus is the deepest of the deep muscles in the front of the forearm, lying deep to the mass of wrist flexor tendons.

Its parallel-oriented muscle fibers run laterally from its origin on the distal anterior ulna.

The fibers cross over the interosseous membrane of the forearm before inserting on the distal anterior ulna, forming a flat quadrate muscle shape.

Also Called

  • Pronator
  • Front of the forearm

Origin, Insertion, Action & Nerve Supply

Muscle Origin Insertion Action Nerve Supply
Pronator Quadratus Distal quarter of anterior surface of ulna Distal quarter of anterior surface of radius
  • Forearm pronation
  • Holds ulna and radius together
Anterior interosseous branch of median nerve (C8-T1)


Note: The chart below only includes direct exercises for the pronator quadratus (and pronator teres). Both pronator muscles are trained indirectly via isometric contraction in exercises involving a pronated grip (e.g. pull up, reverse curl, bench press).

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Stretches & Myofascial Release Techniques:


The following stretches target both the pronator quadratus and pronator teres.

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Self Myofascial Release Techniques

When using these techniques, give special attention to the trigger point shown in the image below.

pronator quadratus trigger point
Note: There were no pre-existing trigger point/referred pain diagrams available, so I made this one from scratch based on this study.
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Common Issues:

  • Overactive/Short Pronator Quadratus: The pronator quadratus may become overactive and short due to overuse from repetitive activities involving the motion of forearm pronation, as well as activities involving excessive isometric contraction of the pronator muscles. That said, a tight pronator quadratus is not likely to lead to injury. What’s more important to worry about is how repetitive pronation can lead to pronator teres injuries: An overactive/short pronator teres can lead to pronator teres syndrome or median nerve compression, which in turn causes pronator quadratus weakness.

Training Notes:

  1. The treatment protocol for overactive/short pronator quadratus is the same as that for overactive/short pronator teres. So if you have tight pronator quadratus, read these guidelines.
  2. If you have no issues with your pronator quadratus (or pronator teres), there’s no significant benefit to direct pronation training. If you insist on doing it anyway, if only to keep the muscles strong and healthy, use the following protocol: Choose one pronator exercise and do it for 2 or 3 sets of 8-15 reps, 1-2 times a week, whenever you train forearms. Use the same training protocol for your supinator to maintain balance between these opposing muscles.
Alex from King of the Gym
Hey! My name is Alex and I'm the founder and author of King of the Gym. I've been lifting weights seriously since 2005 in high school when I started a home gym in my parents' basement. I started writing about fitness in 2009. Then, in 2014, I got into writing home gym equipment reviews and I haven't looked back. My current home gym is in my own house and it's constantly growing and evolving. My goal is to help you build the home gym of your dreams! Read more about me here.

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