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.
Ignoring any maintenance costs, asphalt is generally much cheaper to install than concrete. On average, the cost per square foot for asphalt will run between $2.50 to $4.00. Fluctuations in crude oil prices can cause fluctuations in asphalt prices but the price will remain around this range.oncrete, on the other hand, can run between $4.00 to $6.00 per square foot for basic installation and can cost more depending on different finishes and detail. Itâs not unheard of to have a stained concrete driveway with a smooth finish cost over $15.00 per square foot.