A Cadaveric Study of a Safe and Accurate Electromyographic Needle Approach to the Rhomboid Major

Objective This study aimed to investigate a safe and accurate electromyographic needle insertion site of the rhomboid major (RM) muscle using cadaver dissection. Design Dissection of the trapezius and rhomboid major muscles around the scapula was performed in 18 scapulae from nine fresh cadavers. The point (point A) at which the lateral margin of the lower trapezius muscle crossed the medial border of the scapula and the distal insertion point (point DI) of the rhomboid major muscle to the medial scapula were determined. The midpoint (point M) between points A and DI was also determined. The distance from the inferior angle of the scapula to each point was measured. Results The length of the medial scapula was 12.9 ± 1.2 cm from the root of the scapular spine to the inferior angle of the scapula. Points A, DI, and M were located at a mean distance of 8.4 ± 0.7, 1.8 ± 0.4, and 5.1 ± 0.5 cm proximal to the inferior angle of the scapula, respectively. Conclusions Needle electromyographic examination of the rhomboid major muscle can be performed safely and accurately using the lower part of the rhomboid major muscle, as investigated in this anatomical study.