Which is the origin of the rectus abdominis?

Which is the origin of the rectus abdominis?

• A. Pubic crest, pubic symphysis
• B. Inner surfaces of lower six ribs
• C. Central tendon
• D. Posterior iliac crest

Answer: (A)

The main idea here is understanding where the rectus abdominis starts on the skeleton. This muscle begins at the pubic crest and pubic symphysis, then its fibers run upward to insert on the xiphoid process and the costal cartilages of the lower ribs (usually ribs 5–7). That origin at the pubic region explains how the muscle can flex the trunk and help stabilize the pelvis when it contracts. The other options refer to different structures: the inner surfaces of the lower six ribs belong to the transverse abdominis, not the rectus abdominis. The central tendon is a term more associated with the diaphragm’s aponeurosis and related structures, not the origin of this muscle. The posterior iliac crest is a common origin site for muscles in the back and lateral trunk, not for the rectus abdominis.

The main idea here is understanding where the rectus abdominis starts on the skeleton. This muscle begins at the pubic crest and pubic symphysis, then its fibers run upward to insert on the xiphoid process and the costal cartilages of the lower ribs (usually ribs 5–7). That origin at the pubic region explains how the muscle can flex the trunk and help stabilize the pelvis when it contracts.

The other options refer to different structures: the inner surfaces of the lower six ribs belong to the transverse abdominis, not the rectus abdominis. The central tendon is a term more associated with the diaphragm’s aponeurosis and related structures, not the origin of this muscle. The posterior iliac crest is a common origin site for muscles in the back and lateral trunk, not for the rectus abdominis.