<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
Skip Navigation

Smooth, Skeletal, and Cardiac Muscles

The human body possesses skeletal, smooth and cardiac muscles, each having a distinct function.

Atoms Practice
Estimated5 minsto complete
Practice Smooth, Skeletal, and Cardiac Muscles
This indicates how strong in your memory this concept is
Estimated5 minsto complete
Practice Now
Turn In
Smooth, Skeletal, and Cardiac Muscles

What exactly are muscles?

Does the word "muscle" make you think of the biceps of a weightlifter, like the man in pictured above? Muscles such as biceps that move the body are easy to feel and see, but they aren’t the only muscles in the human body. Many muscles are deep within the body. They form the walls of internal organs such as the heart and stomach. You can flex your biceps like a body builder, but you cannot control the muscles inside you. It’s a good thing that they work on their own without any conscious effort on your part, because movement of these muscles is essential for survival.

What Are Muscles?

The muscular system consists of all the muscles of the body. Muscles are organs composed mainly of muscle cells, which are also called muscle fibers. Each muscle fiber is a very long, thin cell that can do something no other cell can do. It can contract, or shorten. Muscle contractions are responsible for virtually all the movements of the body, both inside and out. There are three types of muscle tissues in the human body: cardiac, smooth, and skeletal muscle tissues. They are shown in Figure below and described below.

Types of muscle tissue

Types of Muscle Tissue. Both skeletal and cardiac muscles appear striated, or striped, because their cells are arranged in bundles. Smooth muscles are not striated because their cells are arranged in sheets instead of bundles.

Smooth Muscle

Muscle tissue in the walls of internal organs such as the stomach and intestines is smooth muscle. When smooth muscle contracts, it helps the organs carry out their functions. For example, when smooth muscle in the stomach contracts, it squeezes the food inside the stomach, which helps break the food into smaller pieces. Contractions of smooth muscle are involuntary. This means they are not under conscious control.

Skeletal Muscle

Muscle tissue that is attached to bone is skeletal muscle. Whether you are blinking your eyes or running a marathon, you are using skeletal muscle. Contractions of skeletal muscle are voluntary, or under conscious control. When skeletal muscle contracts, bones move. Skeletal muscle is the most common type of muscle in the human body.

Cardiac Muscle

Cardiac muscle is found only in the walls of the heart. When cardiac muscle contracts, the heart beats and pumps blood. Cardiac muscle contains a great many mitochondria, which produce ATP for energy. This helps the heart resist fatigue. Contractions of cardiac muscle are involuntary, like those of smooth muscle. Cardiac muscle, like skeletal muscle, is arranged in bundles, so it appears striated, or striped.


  • There are three types of human muscle tissue: smooth muscle (in internal organs), skeletal muscle, and cardiac muscle (only in the heart).


  1. Compare and contrast the three types of muscle tissue.
  2. What can muscle cells do that other cells cannot?
  3. Why are skeletal and cardiac muscles striated?
  4. Where is smooth muscle tissue found?
  5. What is the function of skeletal muscle? Give an example.

    Notes/Highlights Having trouble? Report an issue.

    Color Highlighted Text Notes
    Please to create your own Highlights / Notes
    Show More


    cardiac muscle Involuntary, striated muscle found only in the walls of the heart.
    muscle fiber Long, thin muscle cell that has the ability to contract, or shorten.
    muscular system Human body system that includes all the muscles of the body.
    skeletal muscle Voluntary, striated muscle that is attached to bones of the skeleton and helps the body move.
    smooth muscle Involuntary, nonstriated muscle that is found in the walls of internal organs such as the stomach.
    striated Striped appearance of cardiac and skeletal muscle.

    Image Attributions

    Explore More

    Sign in to explore more, including practice questions and solutions for Smooth, Skeletal, and Cardiac Muscles.
    Please wait...
    Please wait...
    Add Note
    Please to create your own Highlights / Notes