six muscle rule

What do muscles do to create movement?

They contract and pull; they do not push.

What happens to a muscle during contraction?

It develops tension and often shortens.

What are a muscle's attachments called?

Origin and insertion.

What is the origin of a muscle?

Usually the more stationary attachment.

What is the insertion of a muscle?

Usually the attachment that moves more during contraction.

What does a flexor muscle do?

Decreases the angle at a joint.

What does an extensor muscle do?

Increases the angle at a joint.

How do opposing muscle pairs work?

One muscle produces an action while the opposing muscle controls or reverses it.

Why do muscles usually cross joints?

So their contractions can produce movement at those joints.

How can muscle fiber direction help explain function?

It helps indicate the direction in which the muscle pulls.