Ann Rehabil Med.  2015 Feb;39(1):39-46. 10.5535/arm.2015.39.1.39.

Anatomical Basis of Pronator Teres for Electromyography Needle Placement Using Ultrasonography

• Park MK
• Cheong IY
• Kim KH
• Park BK
• Kim DH

• KMID: 2273017
• DOI: http://doi.org/10.5535/arm.2015.39.1.39

Abstract

OBJECTIVE
To find the optimal needle insertion site for needle electromyography of the pronator teres (PT) muscle among commonly used sites.
METHODS
Fifty forearms of 25 healthy subjects were evaluated. Four expected needle insertion points were designated as follows. Point 0 was positioned at the midpoint between the medial epicondyle and medial border of biceps tendon in the elbow crease. Points 1, 2, and 3 were located 2 cm, 3.5 cm and 5 cm distal to point 0, respectively. We assumed that the thickness of PT and the distances between a vertical line from each point to the medial margin of the PT were significant parameters for finding the optimal site. Thus, we measured these parameters through ultrasonographic examination.
RESULTS
In men, the PT was thickest at point 2, and in women, at point 1. The distance between the expected needle insertion line and medial margin of PT was longest at point 1 in both men and women, and was statistically significant compared to points 2 and 3. Both men and women had neurovascular bundles located lateral to the expected needle insertion line.
CONCLUSION
The most appropriate and safe needle electromyographic insertional site for the PT is 2-3.5 cm distal to the mid-point between the biceps tendon and medial epicondyle in the elbow crease and the needle should be inserted upward and medial.

Keyword

Forearm; Electromyography; Ultrasonography

MeSH Terms

Elbow
Electromyography*
Female
Forearm
Humans
Male
Needles*
Tendons
Ultrasonography*

Figure

• 

  Fig. 1 Ultrasonography of the forearm with the transducer located at the four sites of the forearm in transverse plane. Point 0, the mid-point between the biceps tendon and medial epicondyle in the elbow crease; point 1, 2 cm distal to point 0; point 2, 3.5 cm distal to point 0; point 3, 5 cm distal to point 0.

• 

  Fig. 2 Transverse view of ultrasonographic images with schematic drawing obtained at the forearm of a female at 2 cm distal to the elbow crease (point 1; A) and at 3.5 cm distal to the elbow crease (point 2; B). Needle insertion site presents as a hypoechoic focus with well-defined posterior acoustic shadowing (arrow). PT, pronator teres muscle; A, ulnar artery; MN, median nerve; S_PT1, the distance between each point and the upper margin of the pronator teres; S_PT2, the distance between each point and the lower margin of the pronator teres; P_PT1, the distance between the vertical line of each point and the medial margin of the pronator teres; P_PT2, the distance between the vertical line of each point and the lateral margin of the pronator teres; P_MN, the distance between the vertical line of each point and the medial margin median nerve; P_A, the distance between the vertical line of each point and the medial margin of brachial or ulnar artery; A_MN, the angle between the vertical line of the each point and the medial border of the median nerve; A_A, the angle between the vertical line of the each point and the medial border of the brachial or ulnar artery.

• 

  Fig. 3 In men, a schematic drawing of relationship of the distance between the vertical needle insertion line (red arrow) and the medial or lateral margin of the pronator teres (orange oval), the distance between the vertical needle insertion line and the medial margin of median nerve (yellow circle), and the distance between the skin (yellow dot line) and upper or lower margin of pronator teres.

• 

  Fig. 4 In women, schematic drawing of relationship the distance between the vertical needle insertion line (red arrow) and the medial or lateral margin of the pronator teres (orange oval), the distance between the vertical needle insertion line and the medial margin of the median nerve (yellow circle), and the distance between skin (yellow dot line) and upper or lower margin of pronator teres.

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