The structure of skeletal muscle
Skeletal muscles are actually comprised of several smaller structures. The following components make up the structure of skeletal muscle. They are listed in order of largest to smallest.
Epimysium
The connective tissue that surrounds the entire muscle belly.
Fasciculi
A bundle of muscle fibres.
Perimysium
The name of the connective tissue that surrounds each bundle of muscle fibres (fasiculi).
Endomysium
The name of the connective tissue that surrounds each muscle fibre.
Muscle Fibre
Approximately the thickness of a human hair. Containing smaller fibres called myofibrils.
Myofibril
Found within muscle fibres. Containing the contractile proteins (myofilaments) actin and myosin.
Sarcomere
A structural unit (section) of a myofibril.
Actin
A thin myofilament.
Mysoin
A thick myofilament.
Sliding filament theory
According to the sliding filament theory, stimulus from the nervous system and the release of ATP causes the myosin (thick) filaments to attach themselves to the actin (thin) filaments via their hook like projections known as cross bridges. These cross bridges then move (nod) also known as the power stroke causing the actin to slide over the myosin which intern causes the muscle sarcomere to shorten (contract).