Pronator Quadratus

Original Editor - Kakshya Rupakheti

Top Contributors - Kakshya Rupakheti and Amanda Ager

Description

Pronator Quadratus is a deep-seated,short, flat and quadrilateral muscle with fibres running in a parallel direction.[1] The pronator quadratus muscle is compacted in a small closed compartment, covered by the interosseous membrane dorsally and distally and by its own fascia on the volarly.[2] In the anatomical and functional literature, the muscle has been neglected to a high extend.A study shows that the muscle consist of two different heads. The superficial head which is the prime mover in forearm pronation, and the deep head which is dynamic stabilizer of radioulnar joint.[3]

Origin

Muscle arises from the oblique ridge on the anterior surface of the distal fourth of the Ulna.[1]

Insertion

Muscle is inserted in lateral border and anterior surface of the distal fourth of the radius.[1]

Nerve

Anterior interosseous nerve, a branch of the median nerve (C8-T1) with 12.25 cm of average length.[2][4]

Artery

It is vascularized by the anterior interosseous artery with an average length and diameter of 12cm and 2.25 cm respectively.[2][4]

Function

The action of the pronator teres and pronator quadratus muscle result in the pronation of radioulnar joint.Contraction of this muscle pulls the distal end of radius over the ulna, resulting in pronation of the radioulna joint.[5]

Length

The mean length of the muscle is 6 cm.[2]

Width

Mean width of the muscle is 3.5cm.[2]

Assessment

Palpation

It can neither be palpated nor be observed as it is the deepest muscle of the forearm.[1]

Clinical Relevance

Myofascial Trigger point (TrP)

Pronator Quadratus muscle has two main referred pain pattern of the TrP.Most commonly pain spreads into the medial aspect of the forearm both distally and proximally.In many cases, the pain is referred proximally to the medial epicondyle and distally to the fifth digit of the hand.Pain also spread distally to the third and fourth finger, which is the second most common pattern.[6]

Pronator Spasticity

The injection of neurolytic agents such as Botulinum toxin, phenol or alcohol is used into the motor point of the pronator Quadratus for the management of pronator spasticity in stroke patients.[1]

AIN lesions

The electrophysiologic diagnosis of AIN lesions is done by using the Pronator Quadratus muscle which is the key muscle for this diagnosis procedure.[1]

Distal Radius Fracture

Volar plating is the most popular method for the treatment of this fracture and the complication of this method is flexor tendon rupture which can be protected by repairing the pronator quadratus muscle during the surgery.[7]Fixing the distal radius fracture with preserving the pronator quadratus muscle can account for better pronation movement, better stability of radioulnar joint,good grip,reduce pain which all result in better wrist function in early post operative period.[8]

Treatment

Stretching

[9]

Strengthening

[10]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Choung PW, Kim MY, Im HS, Kim KH, Rhyu IJ, Park BK, Kim DH. Anatomic characteristics of pronator quadratus muscle: a cadaver study. Annals of rehabilitation medicine. 2016 Jun;40(3):496.
  2. 2.0 2.1 2.2 2.3 2.4 Créteur V, Madani A, Brasseur JL. Pronator quadratus imaging. Diagnostic and Interventional Imaging. 2012 Jan 1;93(1):22-9.
  3. Stuart PR. Pronator quadratus revisited. Journal of Hand Surgery. 1996 Dec;21(6):714-22.
  4. 4.0 4.1 Carlson TL, Bhandari L, Chang J, Konofaos P. Pronator quadratus muscle flap: a preliminary cadaveric study. European Journal of Orthopaedic Surgery & Traumatology. 2020 Jan 1;30(1):103-7.
  5. Standring S, Ellis H, Healy J, Johnson D, Williams A, Collins P, Wigley C. Gray's anatomy: the anatomical basis of clinical practice. American journal of neuroradiology. 2005 Nov;26(10):2703.
  6. Hwang M, Kang YK, Kim DH. Referred pain pattern of the pronator quadratus muscle. Pain. 2005 Aug 1;116(3):238-42.
  7. Tahririan MA, Javdan M, Motififard M. Results of pronator quadratus repair in distal radius fractures to prevent tendon ruptures. Indian journal of orthopaedics. 2014 Aug;48:399-403.
  8. Jian F, Kai C, Hui Z, Bo J, Feng Y, Xiaozhong Z, Jiong M, Guangrong Y. Effect of fixing distal radius fracture with volar locking palmar plates while preserving pronator quadratus. Chinese Medical Journal. 2014 Aug 20;127(16):2929-33.
  9. Pronator Quadratus stretch
  10. Pronator Quadratus Strengthening