Question

what helps muscles to contract and expand

Answer 1

When you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. This increases the space in your chest cavity, into which your lungs expand. The intercostalmuscles between your ribs also helpenlarge the chest cavity. They contractto pull your rib cage both upward and outward when you inhale.


Hope it's help u

Answer 2

spinal cord is the correct answer