A bilateral muscle of the lateral chest that begins at the fifth ribs and inserts into the anterior iliac crest, serving the function of compressing the abdomen and maintaining an upright posture.
Either of a pair of muscles of the lower trunk originating on the lower eight ribs and inserted in the iliac crest and linea alba. Each muscle laterally flexes the vertebral column; both muscles together flex the vertebral column and compress the abdomen. The muscles are controlled by the intercostal nerves VII through XII.