- 1 Description
- 2 Length
- 3 Width
- 4 Assessment
- 5 Clinical Relevance
- 6 Treatment
- 7 References
Pronator Quadratus is a deep-seated, short, flat, and quadrilateral muscle with fibres running in a parallel direction. The pronator quadratus muscle is compacted in a small closed compartment, covered by the interosseous membrane dorsally and distally and by its own fascia volarly. In the anatomical and functional literature, the muscle has been neglected to a high extend. A study shows that the muscle consists of two different heads. The superficial head was the prime mover in forearm pronation and the deep head which is a dynamic stabilizer of the radioulnar joint.
The action of the pronator teres and pronator quadratus muscle result in the pronation of the radioulnar joint. Contraction of this muscle pulls the distal end of the radius over the ulna, resulting in the Pronation of the radioulnar joint.
The mean length of the muscle is 6 cm.
The mean width of the muscle is 3.5cm.
It can neither be palpated nor be observed as it is the deepest muscle of the forearm.
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.P ain also spread distally to the third and fourth finger, which is the second most common pattern.
Anterior Interosseous Nerve (AIN) lesions
The electrophysiologic diagnosis of AIN lesions is done by using the Pronator Quadratus muscle which is the key muscle for this diagnostic procedure.
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.Fixing the distal radius fracture with preserving the pronator quadratus muscle can account for better pronation movement, better stability of the radioulnar joint, good grip, reduce pain which all result in better wrist function in the early postoperative period.
StretchingWhen the pronator Quadratus muscle is tight, it sometimes mimics Carpal Tunnel Syndrome. Many musicians put the forearm in pronation for the maximum time which also results in the tightness of this muscle. For right-hand Pronator Quadratus stretch, take the right hand (little finger) towards the sternum i.e., supination. With the other hand(left) push the right hand towards the belly which increases the wrist flexion and for excessive supination push the right elbow forward. For the stretch, there should be wrist flexion and supination movement.
StrengtheningMuscle can be strengthen using theraband, flex-bars, weight cuffs, dumbells. First, place the hand in supination and grab the end pf flex-bar and then pronate the forearm. Resistance is used depending upon the condition of patients/clients.
- 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.
- Créteur V, Madani A, Brasseur JL. Pronator quadratus imaging. Diagnostic and Interventional Imaging. 2012 Jan 1;93(1):22-9.
- Stuart PR. Pronator quadratus revisited. Journal of Hand Surgery. 1996 Dec;21(6):714-22.
- 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.
- 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.
- Hwang M, Kang YK, Kim DH. Referred pain pattern of the pronator quadratus muscle. Pain. 2005 Aug 1;116(3):238-42.
- 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.
- 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.
- Dan Hellman. Pronator Quadratus stretch. Available from:https://www.youtube.com/watch?v=oeaANiijjY4 [last accessed 7/10/2020]
- Jamie Dreyer. Pronator Strengthening. Available from:https://www.youtube.com/watch?v=g_Mx7p2lbrY[last accessed 7/10/2020]