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Skeletal muscles are a type of muscle that interacts with your skeleton in order to allow for voluntary movement. Skeletal muscles are the most common type of muscle in your body.
To look at how skeletal muscles work with the skeletal system, use the biceps and triceps found in our upper arm as an example:
Tendons are what connect muscle to bone or to other muscles. They work to stabilize joints and are made of dense connective tissue. Tendons are what actually connect our muscle to our bone at the origin and insertion.
The origin is the end of a muscle that attaches to a stable bone. If you use the diagram above as an example, the stable bone is the scapula, and the origin is where the bicep is attached. The insertion, then, is the movable end of the muscle that attaches to a bone.
Keep in mind that the biceps and triceps are an example of skeletal muscles working in pairs. They work antagonistically with each other. Later on, you will look at this in more depth, but for now, it is important to note that some skeletal muscles work in groups this way.
We're going to talk a little bit more about the structure of skeletal muscles themselves.
Let's continue to use the bicep as an example and look at the inside of the muscle. The covering of our bicep muscle is called the outer sheath. Within that, we have bundles of fibers (remember from the previous lesson, "fibers" are what we call the multinucleated skeletal muscle cells). Within those fibers, we have something called myofibrils. Myofibrils are long chains of myofilaments. Myofilaments are a bunch of proteins (mostly actin and myosin).
So, the skeletal muscle is made up of all of these bundles of fibers. Fibers contain myofibrils, and myofibrils contain units that allow for muscle contractions—they contain something called a sarcomere, which is the basic unit of muscle contraction.
Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND