Biology / Unit 13 Bio 3111 short lesson, about 20 seconds
Skeletal Muscle Organization: Fascicle to Sarcomere
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The idea
Skeletal muscle organizes hierarchically: a muscle bundles fascicles, each fascicle bundles muscle fibers, each fiber bundles myofibrils, and each myofibril divides into repeating contractile units called sarcomeres.
In practice
A single muscle fiber can contain thousands of myofibrils running its full length.
Where people slip
A muscle "fiber" is one elongated cell, not a bundle of separate cells despite the bundling language at every larger level.
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