Currently Internet Explorer is not working properly with our website. Please use the Chrome, Firefox or Safari browsers for a better user experience.

Muscular System

You do not have access to this lesson.

The following is a limited nonfunctional preview of the actual lesson.



Preview mode...

Agonist and Antagonist

Preview mode...


Muscles are bands of stringy tissue found in virtually every living creature.  Muscle is responsible for contracting and carrying out any number of tasks necessary for development within every part of the body. The human body is comprised of an entire network of muscles.  Muscle tissue has a wide variety of capacities and functions.

  • Movement - The skeletal muscles allow us to move the various movable parts of our bodies. Additionally, muscles within certain organs work to move both solids and liquids through them.
  • Maintenance of Posture - In order to keep us walking in an upright state, our skeletal muscles must contract persistently to maintain an upright stance and to allow our bodies to remain in either standing or seated positions.
  • Joint Stabilization - The body’s muscular system is also important to the body's ability to support its weight and to fortifying the joints.
  • Heat Generation - Muscle constrictions deliver warmth that plays a key role in keeping the body’s temperature regulated at 98.6°F.


Muscle Types


The human body contains three types of muscle.

Skeletal Muscle

Skeletal Muscles, also called striated muscle, are those which join to bones and have the primary responsibility of contracting to encourage development of our skeletons and allow us to move. Their appearance is defined by a type of "stripy" look of their Actin and Myosin.

Skeletal muscles are also sometimes referred to as voluntary muscles due to the fact that we have coordinated control over them. Not all filaments inside skeletal muscles are the same. various fiber types contract at various paces and, as such, are suited to various sorts of action.

Smooth Muscle

Smooth muscle differs from skeletal muscle in that it doesn't have the stripy appearance. It is also often called involuntary muscle due to our inability to consciously control it. Smooth muscle is found in the dividers of empty organs like the stomach, the esophagus, and bronchi. 

Cardiac Muscle

Cardiac Muscle is also known as heart muscle. This sort of muscle is found exclusively in the dividers of the heart. It shares similarities with skeletal muscles, in that it is striated, but shares the involuntary control of smooth muscle. It is under the control of the autonomic sensory system and, despite not receiving nervous input, is able to carry out any number of necessary functions in large part because of the presence of its pacemaker cells.

Heart muscle is very resistant to weakness because of the nearness of an extensive number of mitochondria, myoglobin, and a decent blood supply. Cardiac muscle tissue assumes the most vital part in the withdrawal of the atria and ventricles of the heart. It causes the rhythmic thumping of the heart, pumping the blood and its substance all through the body as a result.

Where These Muscles are found in the Body

Skeletal muscle is attached to skin and bones, and cardiac muscle is attached to the walls of heart. Smooth muscle is in walls of hollow organs, intrinsic eye muscles, airways, and large arteries.  When it comes to their connective tissue, skeletal muscle components are epimysium, perimysium, and endomysium.  For cardiac muscle, there are endomysium attached to the fibrous skeleton of heart.  The smooth muscle component is endomysium, found among the body’s organs and veins.


Our muscles generate body heat, stabilize our joints, maintain out posture, and allows for movement, both voluntary and involuntary. Skeletal muscles, also called striated or voluntary muscles, attach to the skeleton and the skin and allow for the movement of the body itself. Smooth, or involuntary muscles make up many organs in the body. While movement still occurs in this muscle type, those movements aid in vital functions, like digestion, and we're not consciously in control of them. Cardiac muscle is similar to skeletal muscle in that it has a similar appearance, but it's found only in the heart, and its movement is involuntary.

Demonstration mode. Purchase course to view.

This is the default dialog which is useful for displaying information. The dialog window can be moved, resized and closed with the 'x' icon.