Ann Rehabil Med.  2016 Jun;40(3):496-501. 10.5535/arm.2016.40.3.496.

Anatomic Characteristics of Pronator Quadratus Muscle: A Cadaver Study

• Choung PW
• Kim MY
• Im HS
• Kim KH
• Rhyu IJ
• Park BK
• Kim DH

• KMID: 2327612
• DOI: http://doi.org/10.5535/arm.2016.40.3.496

Abstract

OBJECTIVE
To identify the anatomic characteristics of the pronator quadratus (PQ) muscle and the entry zone (EZ) of the anterior interosseous nerve (AIN) to this muscle by means of cadaver dissection.
METHODS
We examined the PQ muscle and AIN in 20 forearms from 10 fresh cadavers. After identifying the PQ muscle and the EZ of the AIN, we measured the distances from the midpoint (MidP) of the PQ muscle and EZ to the vertical line passing the tip of the ulnar styloid process (MidP_X and EZ_X, respectively) and to the medial border of the ulna (MidP_Y and EZ_Y, respectively). Forearm length (FL) and wrist width (WW) were also measured, and the ratios of MidP and EZ to FL and of MidP and EZ to WW were calculated.
RESULTS
The MidP was found to be 3.0 cm proximal to the ulnar styloid process or distal 13% of the FL and 2.0 cm lateral to the medial border of the ulna or ulnar 40% side of the WW, which was similar to the location of EZ. The results reveal a more distal site than was reported in previous studies.
CONCLUSION
We suggest that the proper site for needle insertion and motor point block of the PQ muscle is 3 cm proximal to the ulnar styloid process or distal 13% of the FL and 2 cm lateral to the medial border of the ulna or ulnar 40% side of the WW.

Keyword

Pronator quadratus; Median nerve; Electromyography; Cadaver

MeSH Terms

Cadaver*
Electromyography
Forearm
Median Nerve
Needles
Ulna
Wrist

Figure

• 

  Fig. 1 The origin and insertion site of the pronator quadratus (PQ) muscle was identified (A). The anterior interosseous nerve (AIN) was identified and branches to the PQ muscle were observed (B). L_UP, the vertical line passing the tip of ulnar styloid process; O1, the proximal origin site of the PQ muscle; O2, the distal origin site of the PQ muscle; I1, the proximal insertion site of the PQ muscle; I2, the distal insertion site of the PQ muscle; MidP, the midpoint of the PQ muscle; MidP_X, the distance from MidP to L_UP; MidP_Y, the distance from MidP to the medial border of the ulna; EZ, the entry zone of AIN to the PQ muscle; EZ_X, the distance from EZ to L_UP; EZ_Y, the distance from EZ to the medial border of the ulna.

• 

  Fig. 2 Plot of the locations of entry zone (EZ) in the pronator quadratus muscle. The x axis is the distance from the vertical line passing the ulnar styloid process to the EZ, and the y axis is the distance from the medial aspect of the ulna to the EZ.

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