What is the origin of the internal abdominal oblique muscle?

The internal abdominal oblique muscle originates primarily from the thoracolumbar fascia, the anterior two-thirds of the iliac crest, and the lateral two-thirds of the inguinal ligament. The lateral two-thirds of the inguinal ligament is significant because this area provides a critical attachment point that allows the muscle to function effectively in the movements that involve trunk flexion and rotation, as well as in increasing intra-abdominal pressure. Understanding this origin is essential for recognizing how the muscle contributes to abdominal wall integrity and its involvement in various physical activities and postures.