The field of muscle activity measurement has the potential to be revolutionized by the emergence of SonoMyoGraphy, which offers a noninvasive and high-resolution alternative to electromyography. Electromyography has several limitations, such as difficulty distinguishing primary muscle actions from those of neighboring muscles and inefficiency in scanning deeper muscles. Current work presents the pulse-echo method for the first time that utilizes A-mode ultrasound scans to measure muscle thickness changes in the Extensor Carpi Radialis skeletal muscle during rest and two gestures: grab the bottle and clenched fist. Significant variations in depth measurements were observed between rest and grab the bottle and clenched fist $(p\lt0.05)$, indicating distinct depth characteristics for each gesture. However, the depth difference between grab the bottle and clenched fist $(p=0.09)$ exceeded the significance level of 0.05. A cross-correlation algorithm was then employed to calculate the percentage muscle deformation observed during these gestures. The mean ± standard deviation of muscle deformation in a clenched fist (22.60 ± 27.95%) was found to be 8.36 ± 2.36% higher than in grab the bottle (14.24±25.59%). Our results demonstrate the reliability of this method and its potential for SonoMyoGraphy and next-generation prosthesis control.