• Striated
• Voluntary (Somatic)
• Connected to at least two bones

Muscle Fibers

Muscle cells

• Runs the length of the muscle
• Mulitnucleated
• Innervated by only one muscle neuron

The muscle fiber's contractile machinery.

• Bundle of overlapping thick/think filaments

Saclike membranous network that surrounds the myofibrils

• Role in activation of muscle contractions
• Function to store calcium ions and release when a muscle is stimulated to contract

Transverse Tublules

(T Tubules)

Structures that transmit action potentials from the sarcolemma to cell's interior, releasing calcium from sarcoplasmic reticulum.

Filaments composed of myosin that form part of the contractile machinery of a muscle cell.

• Each thick filament surrounded by 6 thin filaments

Filaments composed of actin that form part of the contractile machinery of a muscle cell.

• Also contain troponin and tropomyosin in striated muscle cells

Functional unit of skeletal muscle.

• Area between two Z lines

Cytoskeleton protein that connects thin filaments of adjoining sarcomeres.

Supporting proteins that hold thick filaments together.

Stacked set of thick filaments plus portions of thin filaments that overlap both ends of thick filaments.

I Band

Regulatory protein that fastens down each end of the tropomyosin molecules so they do not move from myosin-binding sites.

• Contains calcium-binding site that allows contraction

Heads of the intertwinning thck filaments that are wrapped around each other and actively generates a muscles mechanical force. 

• Bridge gap between thick and thin filament
• Contains an actin-binding site
• Contains ATPase site

Crossbridge Cycle

Mechanism that drives muscle contraction.

• This is characterized by the stroke forward when the myosin binds to actin of thin filament.