Serratus posterior superior — helps you breathe in Serratus posterior inferior — helps you breathe out Superficial and intermediate muscles are also sometimes called immigrant muscles .

First, "we discovered modifications in the insertion of three important respiratory muscles: scalenus posterior, serratus anterior, and serratus posterior superior," they write in their article.

The superior border of the dissection is ... the long thoracic nerve, which innervates the anterior serratus muscle ... The intercostobrachial nerve provides sensation to the posterior ...

The posterior serratus muscle is on the back, roughly at the bottom of the ribcage. As relayed by Adam McCalvy of MLB.com, it’s rare for a baseball player to strain this muscle, ...