Muscle Contraction

Science Masterpiece

Muscle Types

• Muscles are a group of elastic fibers that hold the body together and control all movement.
• There are 3 types of muscles:

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• Muscles can be voluntary or involuntary.
• Cardiac and Smooth Muscle are involuntary; they work with out you thinking about it.
• Skeletal Muscles are voluntary; your brain makes the muscles move.

Muscle Facts

• Skeletal Muscles attach to your bones by tendons.
• Tendons are tough, fibrous cords.

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• Muscles work in pairs to help your body move.
• One muscle contracts and the other relax.
• We have more then 600 muscles in our body.

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Tendons and Ligaments

• Ligaments are similar to tendons, but the connect bone to bone.
• Fibers in muscles or tendons can get torn. These injuries are called “Strains” or “Pulls”
• These injuries to Ligaments are called “Sprains”.
• Most “Strains” heal on their own with rest and ice packs.

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Anatomy of the Arm

• There are 3 bones that make up the arm.
• The largest and upper bone is the Humerus.
• The 2 smaller bones connecting to the Humerus are the Ulna and Radius.
• The Radius is on the side with your thumb.
• The Ulna is on the side with your pinkie.

Muscles of the Arm

• The 2 major muscles of the upper arm are the Biceps and Triceps.
• These muscles work in pairs. When you flex your arm, your Biceps contract and Triceps relax.
• When you extend your arm, your Biceps relax and your Triceps contracts.

Experiment Time

• Build an Arm Model
• Once Constructed, observe the contraction and relaxation of the muscles with the flexion and extension of the arm.

Conclusion

• When the Ulna and Radius flex towards the Humerus the biceps contracts and the triceps stretches.
• How did this model work like your arm?
• What would happen if one muscle doesn’t work properly?