Which rib is associated with the insertion of the quadratus lumborum?

Which rib is associated with the insertion of the quadratus lumborum?

• A. Twelfth rib.
• B. Tenth rib.
• C. Eleventh rib.
• D. Ninth rib.

Answer: (A)

The insertion point of the quadratus lumborum is the inferior border of the twelfth rib (and the transverse processes of L1–L4). That makes the twelfth rib the rib associated with its insertion. This location explains its role in depressing the last rib during forced expiration and helping stabilize the lumbar region when the trunk moves. The other ribs listed do not serve as the insertion for this muscle.

The insertion point of the quadratus lumborum is the inferior border of the twelfth rib (and the transverse processes of L1–L4). That makes the twelfth rib the rib associated with its insertion. This location explains its role in depressing the last rib during forced expiration and helping stabilize the lumbar region when the trunk moves. The other ribs listed do not serve as the insertion for this muscle.