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Skeletal Muscles

Skeletal Muscles

Description:

This lesson will describe the structure and function of skeletal muscles.

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Tutorial

What's Covered

We are going to be looking the structure and function of skeletal muscles from two perspectives:

  1. Interaction of Muscle and Bone
  2. The Muscle Itself

1. Interaction of Muscle and Bone

Skeletal muscles are type of muscle that interacts with your skeleton in order to allow for movement, and are the most common type of muscle in your body.

Term to Know

    • Skeletal muscle
    • a form of muscle that contains very long, striated, multinucleated cells; skeletal muscles are the largest form of muscles in the body and attached to the skeleton; these are used for the movement of our bones, generate heat and protect deeper internal organs; skeletal muscles are also the most abundant type of muscle found in the human body

To look at how skeletal muscles work with the skeletal system, use the biceps and triceps as an example:

Skeletalmuscles1.png

These are the muscles found in our upper arm. The portion colored red is the actual muscle tissue, and the portion colored blue is our tendons.

Tendons are what connect muscle to bone, or to other muscles. They work to stabilize joints and are made of a 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, use the diagram above as your example. The stable bone in this case is the scapula, and where the bicep is attached to it is the origin. The insertion, then, is the end of the muscle that attaches to a bone that will move.

Terms to Know

    • Origin
    • a tendon that fixates the muscle to the bone; stationary end of the muscle that performs little to no movement
    • Insertion
    • a tendon that fixates the muscle to the bone; highly moveable end of muscle that performs most of the work as a muscle contracts

Think About It

If we are using the bicep and tricep as our example, where is the insertion attaching to? To answer this, you simply have to think of what moves when you flex your bicep. It is pulling on your forearm, and, since it is the bones your forearm that move, this is the insertion.

Keep in mind that the biceps and triceps are an example of skeletal muscles working in pairs. They work antagonistically of each other. Further 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.


2. The Muscle Itself

We're going to talk a little bit more about the structure of skeletal muscles themselves.

skeletalmuscles2.png
Continuing to use the bicep as our example, let's look at the inside of the muscle. The covering of our biceps muscle is called the outer sheath. Within that, we have bundles of fibers, and within those fibers we have something called myofibrils. Myofibrils, which are long chains of contractile proteins called myofilaments, contain something called a sarcomere which is the unit that allows for muscle contractions. The sarcomere is the basic unit of muscle contraction.

Term to Know

    • Myofibrils
    • long chains of contractile proteins called myofilaments that are located within muscle cells (myocytes)

Summary

Muscle and bone interact to allow us movement. The end of a muscle attached to a stable bone is called the origin. The other end attaches to a bone that moves, and is called the insertion. Tendons are what connect the muscle to the bone. Muscles can work antagonistically in pairs to create movement. The muscle itself is covered by the outer sheath. Within this are bundles of fibers, which contain myofibrils, and myofibrils contain sarcomere, the basic unit of muscle contraction.

Keep up the learning and have a great day!

Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

TERMS TO KNOW
  • Skeletal muscle

    a form of muscle that contains very long, striated, multinucleated cells; skeletal muscles are the largest form of muscles in the body and attached to the skeleton; these are used for the movement of our bones, generate heat and protect deeper internal organs; skeletal muscles are also the most abundant type of muscle found in the human body

  • Myofibrils

    long chains of contractile proteins called myofilaments that are located within muscle cells (myocytes)

  • Origin

    a tendon that fixates the muscle to the bone; stationary end of the muscle that performs little to no movement

  • Insertion

    a tendon that fixates the muscle to the bone; highly moveable end of muscle that performs most of the work as a muscle contracts