Fig. 1

Ultrasound image of the internal oblique abdominal muscle at the second (A) and the fifth visit (B). A spherical hyperechoic spot with a major axis diameter of 5 mm surrounded by a hypoechoic area is shown at the myofascial trigger point in the internal oblique abdominal muscle (A). The hyper- and hypoechoic area disappeared, which changed to an irregular muscle bundle alignment at the same site of A and its vicinity (B). Vertical arrows indicate the outer fascia of the internal oblique abdominal muscle, and dotted arrows indicate the peritoneum. MTrP, myofascial trigger point