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Pronator Quadratus Muscle Anatomy

The pronator quadratus (PQ), as its name indicates, is quadrangular and pronates the forearm. It cannot be palpated or observed, except in dissections, because it is the deepest muscle in the anterior aspect of the forearm.

Pronator Quadratus Muscle Anatomy

Sometimes it is considered to constitute a fourth muscle layer.

The pronator quadratus muscle arises from the oblique ridge on the anterior surface of the distal fourth of the ulna and inserts on the lateral border and anterior surface of the distal fourth of the radius. The pronator quadratus is the only muscle that attaches only to the ulna at one end and only to the radius at the other end.

The pronator quadratus muscle receives the final branch of the anterior interosseous nerve (AIN) a branch of the median nerve.

See Also: Forearm Muscles Anatomy & Function
Pronator Quadratus

The PQ muscle is the prime mover for pronation. The muscle initiates pronation and is assisted by the PT when more speed and power are needed. The pronator quadratus muscle also helps the interosseous membrane hold the radius and ulna together, particularly when upward thrusts are transmitted through the wrist (e.g., during a fall on the hand).

OriginDistal 1/4 of anterior surface of ulna
InsertionDistal 1/4 of anterior surface of radius
InnervationAnterior interosseous nerve from median nerve (C8 and T1) (C8, T1)
Blood SupplyAnterior interosseous artery
ActionPronates forearm; deep fibers bind radius and ulna together

References & More

  1. Clinically Oriented Anatomy – 8th Edition
  2. Clinical Anatomy by Regions, Richard S. Snell.
  3. Choung PW, Kim MY, Im HS, Kim KH, Rhyu IJ, Park BK, Kim DH. Anatomic Characteristics of Pronator Quadratus Muscle: A Cadaver Study. Ann Rehabil Med. 2016 Jun;40(3):496-501. doi: 10.5535/arm.2016.40.3.496. Epub 2016 Jun 29. PMID: 27446787; PMCID: PMC4951369. Pubmed
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