Which muscle originates from pubic crest and pubic symphysis?

Which muscle originates from pubic crest and pubic symphysis?

• A. Rectus abdominis
• B. Diaphragm
• C. External oblique
• D. Quadratus lumborum

Answer: (A)

The important idea is where the muscle attaches at its origin. The muscle that starts at the pubic crest and pubic symphysis is the rectus abdominis. It runs as a vertical band on the front of the abdomen and, from those pubic attachments, fibers elevate upward to insert on the xiphoid process and the costal cartilages of ribs 5–7. This arrangement lets it flex the spine and help compress the abdomen. The other muscles attach in different places: the diaphragm anchors to the xiphoid process, lower ribs, and lumbar vertebrae; the external oblique originates from the outer surfaces of the lower ribs and extends to the iliac crest and linea alba; the quadratus lumborum arises from the iliac crest and adjacent fascia. None of these originate from the pubic crest or pubic symphysis, so they aren’t the correct choice.

The important idea is where the muscle attaches at its origin. The muscle that starts at the pubic crest and pubic symphysis is the rectus abdominis. It runs as a vertical band on the front of the abdomen and, from those pubic attachments, fibers elevate upward to insert on the xiphoid process and the costal cartilages of ribs 5–7. This arrangement lets it flex the spine and help compress the abdomen.

The other muscles attach in different places: the diaphragm anchors to the xiphoid process, lower ribs, and lumbar vertebrae; the external oblique originates from the outer surfaces of the lower ribs and extends to the iliac crest and linea alba; the quadratus lumborum arises from the iliac crest and adjacent fascia. None of these originate from the pubic crest or pubic symphysis, so they aren’t the correct choice.