Iliocostalis is the most lateral component of the erector spinae muscle. Its fascicles are attached to sites that are homologous with the ribs. It assists in extending the back and bending sideward. It arises from the tendinous mass covering the sacrum just lateral to the spinalis dorsi and the longissimus dorsi, but is not contingent with those two, being somewhat separated from them. It has three parts.
When done with incorrect posture, simple daily tasks, such as housecleaning, gardening, lifting heavy objects, and exercising, can cause tightness in back muscles. Poor posture includes slouching in chairs, sitting in hunched-back positions, standing in non-upright positions, and keeping the knees straight when lifting. All these actions lead to tight muscles by either overworking or overstretching the back muscles. Two other common reasons for tight back muscles are conscious psychological stress and subconscious repressed emotions. Stress causes back muscles to tighten in a fight or flight response, thus overworking the muscles and depriving them of energy needed to support the spine. In the short term, back stretching exercises reduce these problems by reducing stress. In the long term, these exercises make the back muscles stronger and longer and thus reduce the possibilities of overworking and overstretching.
Iliocostalis stretch side lying
Iliocostalis stretch kneeling
Iliocostalis stretch standing