Skeletal striated muscle

Your body has many muscles that help you move and do things. One kind of muscle is called skeletal striated muscle. It's called "skeletal" because it's attached to your bones, and "striated" because it looks striped under a microscope.

Skeletal striated muscle is made up of lots of small units called fibers. These fibers are organized into bundles, which are called fascicles. Each fascicle is surrounded by a connective tissue called perimysium.

Inside each fiber, there are tiny structures called myofibrils. They give the muscle fiber its stripy appearance. Each myofibril is made up of even tinier structures called sarcomeres. Sarcomeres are like the little building blocks of the muscle fiber.

When your brain wants you to move a muscle, it sends a message through your nerves to the muscle fibers. The message triggers a series of chemical reactions that cause the myofibrils to contract. When many myofibrils contract together, the fascicles and the entire muscle shorten, causing movement.

Skeletal striated muscle is important for things like running, jumping, and lifting things. It's also the kind of muscle that you can control with your conscious thoughts. So if you decide to lift your arm, your brain sends a message to the muscle fibers to make it happen.