rectus abdominis

noun

rectus ab·​dom·​i·​nis -ab-ˈdäm-ə-nəs 

: a long flat muscle on either side of the linea alba extending along the whole length of the front of the abdomen, arising from the pubic crest and symphysis, inserted into the cartilages of the fifth, sixth, and seventh ribs, and acting to flex the spinal column, tense the anterior wall of the abdomen, and assist in compressing the contents of the abdomen