You may be thinking of the diaphragm. There are others such as the intercostals.
the warm air rises up and moves over the cold air that is already there.
Depends. It could be considered forced convection if the object is also air. It is called jet propulsion when the blast of air comes out of a jet engine, and moves an aircraft.
Dynamics
when air is heated air pressure decreases because the molecules
Air gets hot and it moves upwards in relation to the air that is not as hot
Air moves into the lungs when the diaphragm is flattened. The diaphragm is relaxed (arched) during expiration.
The muscle is the "diaphragm" muscle. It is located beneath the lungs. When it moves down and away, it creates lower pressure around the lungs, and the air pressure outside the body flows into the lungs. When it moves up and in, it compresses the lungs, increasing the pressure to force the air back out.
inhale:- the air pressure in the lungs decreases and air moves in. exhale:-air pressure in the lungs increases and air moves out.
Skeletal Muscles.
heart muscle
The diaphragm moves down to make the lungs expand (inhalation)
muscle fibers contracting
The cardiac muscle
Pulling and contracting is how a muscle moves the bones ....
the diaphragm... ^_^
Buccinator
There are three different muscles * skeletal muscle(moves bones) * smooth muscle(moves organs and blood vessels) * cardiac muscle(heart)