There are three principal layers; 1  External intercostal muscles aid in quiet and forced inhalation. They originate on ribs 1-11 and have their insertion on ribs 2-12. 2  Internal intercostal muscles aid in forced expiration (quiet expiration is a passive process).
Costs. A professional concrete contractor will typically charge $2-$4 per square foot for a simple stain application, including the sealer. A stain application with patterning and sawed lines will typically cost between $4 and $10 per square foot.
Expect to pay approximately $2 to $4 per square foot for concrete staining that involves application of one stain color and protective sealant. Stain projects can also expand to include border designs, stenciling, and multiple colors, which can increase the price to $15 per square foot.