Where does serratus posterior superior insert?

Where does serratus posterior superior insert?

• A. Ribs 7-12
• B. Ribs 2-5
• C. Ribs 1-4
• D. Ribs 5-7

Answer: (B)

Serratus posterior superior is positioned to elevate the upper ribs, so its insertion must be on those ribs that it can lift. It attaches to the upper borders of the second through the fifth ribs, which lets it pull these ribs upward when it contracts and expand the thoracic cage during inspiration. This placement matches its role as an accessory inspiratory muscle. Inserting on ribs 7–12 would correspond to serratus posterior inferior, which pulls the lower ribs down, not up, and inserting on rib 1 or 4 wouldn’t align with its typical short, lateral excursion from the spine to the upper ribs. Therefore, the correct insertion is on the upper borders of ribs 2–5.

Serratus posterior superior is positioned to elevate the upper ribs, so its insertion must be on those ribs that it can lift. It attaches to the upper borders of the second through the fifth ribs, which lets it pull these ribs upward when it contracts and expand the thoracic cage during inspiration. This placement matches its role as an accessory inspiratory muscle. Inserting on ribs 7–12 would correspond to serratus posterior inferior, which pulls the lower ribs down, not up, and inserting on rib 1 or 4 wouldn’t align with its typical short, lateral excursion from the spine to the upper ribs. Therefore, the correct insertion is on the upper borders of ribs 2–5.