Muscles
Types of Muscles
Skeletal muscle contracts and relaxes allowing the skeleton to move. Skeletal muscle is striated. It has the appearance of stripes. |
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Smooth muscles are not striated. They work in rhythmic contractions. Smooth muscle is found in digestive organs and blood vessels. |
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Cardiac muscle is found in the heart. It has striations like skeletal muscle, but is involuntary like smooth muscle. Unlike skeletal muscle, cardiac muscle does not tire allowing the heart to pump continuously. |
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Comparison of Muscle Types
| Skeletal Muscle | Smooth Muscle | Cardiac Muscle |
| Striated | Not striated | Striated |
| Voluntary | Involuntary | Involuntary |
| Tires relatively easily | Does not tire easily | Does not tire |
| Works by contraction and relaxation | Rhythmic contraction called peristalsis | Coordinated contraction and relaxation |
Movement of Skeletal Muscles
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Skeletal muscles work in pairs, for example, the biceps and triceps of the arm. One muscle flexes as the other relaxes. This allows the muscle to move bones at the joints. Tendons connect muscles to bones. Ligaments connect bone to bone. |
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