What are muscles?


Muscles are tissues that contract to move parts of your body. You have different types of muscles:

Skeletal muscle
Smooth muscle
Heart muscle

Skeletal muscles are attached to bones and occur in pairs. For example, biceps muscles bend your elbows and triceps muscles straighten your elbows. Skeletal muscles are voluntary (meaning you move them when you want to).

Smooth muscles surround your arteries, veins and intestines. Smooth muscles in your blood vessels contract and relax to regulate blood flow. The smooth muscles in your intestines contract to move food and stool through your digestive tract. You cannot control your smooth muscles. They do their work without you even thinking about it.

The heart muscle (myocardium) is a special type of muscle that never needs to stop to rest and is not under the control of your will.

How do muscles work?
Muscles generate energy from food and oxygen circulating in the bloodstream. Muscles use this energy to contract (shorten). The larger the muscles and the greater the blood supply, the harder they can contract.

Muscles can only pull, they can't push.
Without a good blood supply, your muscles can't do much work.

Certain types of exercise, for example, lifting weights, can make your muscles bigger and stronger. Other types of exercise, such as running, can give your muscles more endurance (they can work longer).

How do muscles move your body?
For your body to move, muscles must connect one bone to another through a joint.

Muscles are connected to bones by thick cords of tissue called tendons.
When a muscle contracts, the tendons pull on both bones and move them in the direction the joint allows. Because muscles can only contract, if one muscle flexes a joint, you need to contract another muscle on the other side of the joint to straighten it.


October 02, 2023