Levels of organisation
Skeletal muscle is the type of muscle responsible for movement of the skeleton. Its striped appearance is also described as striated. Cardiac muscle and smooth muscle are other muscle types, but they are not responsible for moving the skeleton.
A whole skeletal muscle is built from bundles of muscle fibres. Each fibre is a single specialised muscle cell containing numerous myofibrils, and each myofibril consists of repeating sarcomeres.
This hierarchy allows a large number of contractile protein filaments to be organised within each muscle cell.
Exam Tip: Keep the structural terms distinct. A muscle fibre is a cell, a myofibril lies inside that cell, and a sarcomere is one repeating section of a myofibril. Do not confuse a muscle myofibril with a cellulose microfibril.