The intertransversarii muscles perform which actions?

• A. Extension of the vertebral column and ipsilateral flexion
• B. Extension and contralateral rotation
• C. Flexion of the spine at the lumbar region
• D. Abduction of the rib cage

Answer: (A)

Intertransversarii lie between adjacent transverse processes and act mainly to stabilize the spine. When both sides contract, they contribute to extending the vertebral column; when one side contracts, they produce lateral flexion toward the same side (ipsilateral). They do not drive rib cage movement, nor do they primarily cause flexion of the lumbar spine or contralateral rotation. So the combination of extending the spine and bending it to the same side best matches their actions.