The muscles of the lower back, including the erector spinae and quadratus lumborum muscles, contract to extend and laterally bend the vertebral column. The abdominal muscles also play a major role in the posture and stability to the body and compress the organs of the abdominal cavity during various activities such as breathing and defecation. Working as a team, these muscles contract to flex, laterally bend, and rotate the torso. In addition to providing protection, these core muscles also function in movement of the trunk, posture, and stability of the entire body.Įxtending across the anterior surface of the body from the superior border of the pelvis to the inferior border of the ribcage are the muscles of the abdominal wall, including the transverse and rectus abdominis and the internal and external obliques. Lying exposed between the protective bones of the superiorly located ribs and the inferiorly located pelvic girdle, the muscles of this region play a critical role in protecting the delicate vital organs within the abdominal cavity. The muscles of the abdomen, lower back, and pelvis are separated from those of the chest by the muscular wall of the diaphragm, the critical breathing muscle.
