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Human Body Study

Skeletal Muscle

The voluntary muscle attached to the skeleton — the muscle of deliberate movement. There are roughly 600 of them, making up about 40% of body weight.

The three muscle types and the tendons that anchor them A four-panel plate: three comparative panels of skeletal, cardiac and smooth muscle drawn so the visual differences carry the classification, plus a fourth panel showing skeletal muscle attaching to bone via a tendon. Each panel links to that subject's article. Skeletal muscle long striated multinucleate fibres, attached to bones Cardiac muscle branched cells joined by intercalated discs, with a central nucleus Smooth muscle spindle-shaped cells with a single central nucleus; no striations Tendon — connection to bone a skeletal muscle's belly tapers into a cord of parallel collagen fibres, anchored into bone muscle tendon bone Three muscle types — one mechanism, three cell forms — plus the tendon, by which a skeletal muscle pulls on bone.

Structure

Section titled “Structure”

Bundles of long, striped (striated) fibers; each fiber is a single large cell with many nuclei. Muscles attach to bone via tendons.

How it works

Section titled “How it works”

A nerve signal triggers the release of calcium inside the fiber; the proteins actin and myosin slide past each other, shortening the muscle. Skeletal muscle contracts only when commanded by a nerve.

What it does

Section titled “What it does”
  • Moves the skeleton and maintains posture.
  • Stabilizes joints.
  • Generates heat.

Key idea

Section titled “Key idea”

Skeletal muscle is the only fully voluntary muscle — and because it can only pull, the body arranges it in opposing pairs.