The first objective of this study was to identify the deformation of the median nerve cross-sectional area (MNCSA) at different wrist active and passive holding positions. The second objective was to compare the wrist circumference, wrist width, and w...
The first objective of this study was to identify the deformation of the median nerve cross-sectional area (MNCSA) at different wrist active and passive holding positions. The second objective was to compare the wrist circumference, wrist width, and wrist depth between dominant and non-dominant hands. A total of eight right-handed healthy male adults (age 27.0 ± 3.5 years) participated in this study. Ultrasound examination was performed at the proximal carpal tunnel to examine the median nerve on the transverse plane. A total of three wrist positions were examined, namely, wrist neutral, wrist flexion 30°, and wrist extension 30°, in active and passive holding positions for both dominant and non-dominant hands. Paired t-test showed significant differences between dominant (D) and non-dominant (ND) hands in wrist circumference (D = 15.9 ± 0.6 cm, ND = 15.7 ± 0.6 cm, p<0.05), wrist width (D = 56.3 ± 3.6 mm, ND = 54.0 ± 2.1 mm, p<0.05), and wrist depth (D = 39.6 ± 2.8 mm, ND = 38.3 ± 2.7 mm, p<0.01). The differences of MNCSA between dominant and non-dominant hands were significant (p<0.001) at both active (D = 7.93 ± 0.63 mm<SUP>2</SUP>, ND = 6.98 ± 0.42 mm<SUP>2</SUP>) and passive holding positions (D = 8.22 ± 0.72 mm<SUP>2</SUP>, ND = 7.06 ± 0.44 mm<SUP>2</SUP>). Two-way repeated-measures ANOVA showed that wrist flexion 30° and wrist extension 30° caused significant reductions in MNCSA when compared with wrist neutral (p<0.001) in both active and passive holding positions. However, wrist active and passive holding did not have a significant effect on MNCSA changes. In conclusion, our findings showed that significant reduction of MNCSA was associated with wrist flexion-extension motion and there was significant bilateral asymmetry in physical characteristics of the wrist.