Muscular System
Discover how skeletal, cardiac, and smooth muscle work together to move the body, maintain posture, and keep vital organs functioning.
Explore the muscular system
Use the interactive muscular guide to explore the major muscle groups from head to foot.
Open Innerbody guide →Explore the full muscular system
Rotate and inspect a complete 3D model of the human muscular system, from the neck to the feet.
Open model source →Learn it step by step.
Start with the three types of muscle tissue, then move into the major muscle groups of the upper and lower body, how muscles contract, and the internal structure that makes contraction possible.
The Muscular System
Build the foundation. Learn the functions of the muscular system and the three types of muscle tissue found in the body.
Upper Body Muscles
Explore the muscles of the chest, back, shoulders, and arms that drive upper-body movement.
Lower Body Muscles
Learn the muscles of the hips, thighs, legs, and feet that support body weight and movement.
Muscle Contraction
Discover the sliding filament theory and how nerve signals trigger muscle fibers to generate force.
Skeletal Muscle Structure
Zoom down to the cellular level and learn how muscle fibers are organized into fascicles, myofibrils, and sarcomeres.
Test Your Knowledge
Finished all five lessons? Take the final Muscular System assessment and see how much you remember.
From tissue to mechanism.
The easiest way to understand the muscular system is to move from tissue types to muscle groups to the cellular mechanism: tissue types → muscle groups → contraction and structure.
Muscle tissue types
Learn the three types of muscle tissue and how skeletal muscle attaches to and moves the skeleton.
Major muscle groups
Explore the muscle groups of the upper and lower body and the movements each one produces.
Contraction and structure
See how the sliding filament mechanism and internal muscle structure work together to generate force.