What does the rector spinae does?

Answer 1

The Erector spinæ is a muscle group of the back in humans and animals, which extends the vertebral column (bending the spine such that the head moves posteriorly while the chest protrudes anteriorly). It is also known as sacrospinalisin older texts. A more modern term is extensor spinae,[1] though this is not in widespread use. The name of the muscle is pronounced e-rec-tor speen-aye, or e-rec-tor spinae-ee.