The Muscular System

The muscular system is an organ system which consists of three kinds of muscles: skeletal, smooth, and cardiac muscles. You have more than 600 muscles in your body! This system allows the body to move and circulates blood throughout the body. Combined with the skeletal system, it makes the musculoskeletal system which is responsible for the movement of the human body.

FACIAL MUSCLES

QUADRICEPS

Your face is full of muscles! Unlike other muscles, facial muscles don’t attach directly to bone but rather just attach under the skin. This allows you to contract your facial muscles and make all sorts of different facial expressions. Your tongue is also a muscle - it’s a group of muscles, in fact, that work together to help you talk and chew.

The muscle which makes up the heart is known as cardiac muscle. The muscles of the heart contract to pump blood out and then relax to let blood back in. Cardiac muscle, like smooth muscle, is involuntary and works without any help from you.

Smooth muscles are usually found in sheets, or layers. These muscles are involuntary, which means you can’t control them - your brain tells these muscles what to do without you even needing to think about it. In your digestive system, for example, they tighten and relax to allow food to travel through the body. Smooth muscles push the food back out of the stomach when you’re sick and need to throw up. They are found in your bladder, and they hold in your urine until you get to the bathroom. Smooth muscles also keep your eyes focused.

Skeletal muscles are voluntary which means you can control what they do. These muscles, along with your skeletal system, make up the musculoskeletal system. The skeletal muscles work with your skeleton to give your body strength. Skeletal muscles are usually attached to one end of a bone, they stretch over a joint (where two bones meet) and then attach to another bone. Some of the most powerful skeletal muscles are your calf and thigh muscles, which help you lift and push things.

The muscles on the front of your thighs are known as quadriceps, or quads. You can develop strong, large quadriceps by running, playing sports, or biking. Quadriceps are an example of a skeletal muscle because moving them is voluntary.

“Your Muscles (for Kids) - Nemours KidsHealth.” Edited by KidsHealth Medical Experts, KidsHealth, Nemours Children's Health System, kidshealth.org/en/kids/muscles.html.