Located in the deep surface of the internal oblique muscle, it starts from the inner surface of the inferior six costal cartilage, the thoracolumbar fascia, the iliac crest and the outer side of the inguinal ligament, and the muscle bundle extends laterally forward to form aponeurosis, and passes through the back of the rectus abdominis to form the posterior layer of the rectus abdominis sheath, ending at the white line. The lowest muscle bundle of transverse abdominis muscle and the inner side of the lower edge of aponeurosis participate in the formation of cremaster and inguinal falx respectively.
obliquus internus abdominis
Located in the deep layer of the abdominal external oblique muscle. From thoracolumbar fascia, Iliac Valley and lateral inguinal ligament 1/2, the muscle bundle is fan-shaped, and the posterior muscle bundle rises almost vertically to the lower three ribs. Most of the muscle bundles extend to the aponeurosis, and the anterior and posterior layers wrap the rectus abdominis at the lateral edge, forming the anterior and posterior layers of the rectus abdominis sheath, and finally reaching the white line of the abdominal midline.
The muscle bundle at the lower part of the internal oblique muscle goes forward and downward, crosses the front of the spermatic cord, continues to the aponeurosis, and merges with the aponeurosis of the transverse abdominis muscle to form the inguinal falx, or symphysis tendon, which ends at the inner end of the pubic comb and is close to the pubic tubercle. The lowest part of the internal oblique muscle is divided into some fine muscle bundles.
Refer to the above? Baidu encyclopedia-abdominal muscles