Muscle Anatomy (Muscle cell)

Skeletal muscle

Shape: elongated, striated cylindrical cells

Nucleus: Multinucleated

Control: voluntary

Found: attached to skeletal bones

Smooth Muscle

Shape: spindle

Nucleus: Uni-nucleated

Control: Involuntary

Found: in the walls of soft organs or blood vessels

Cardiac Muscle

Shape: Branched, striated cells with intercalated discs to separate one cell from another

Nucleus: Uni-nucleated

Control: Involuntary

Found: in the walls of heart muscle

Entire Skeletal Muscle

Highest order of muscle anatomy hierarchy

Epimysium

Membrane that wraps around the entire skeletal muscle

Perimysium

Membrane that wraps around a fascicle

Endomysium

Membrane that is found within a fascicle and around muscle fibers

Sarcolemma

The plasma membrane of a muscle cell

Fascicle

Consists of bundles of muscle fibers

Muscle Fiber

Consists of bundles of myofibrils; also called a muscle cell

Myofibril

Consists of bundles of myofilaments

Myofilaments

The smallest unit of hierarchy of skeletal muscle tissue; examples includes myosin and actin. Bundles of myofilaments make up myofibrils.

Myosin

Thick myofilament; consists of golf club-like heads that bind to actin

Actin

Thin myofilament; contains two compounds (troponin and tropomyosin)

Sarcomere

The single contractile unit of muscle tissue; the distance from one Z line to another Z line

I band

Area that only contains actin filament; also called the Light Bands

A band

Area that contains actin and myosin filaments that overlap; also called Dark Bands

H zone

Area that only includes myosin filament (#7)

Z line

Attachment site that serves to anchor actin filaments in place

M line

Attachment site that serves to anchor myosin filaments in place

List the hierarchy of skeletal muscle tissue from smallest to largest

Myofilament, sarcomere, myofibrils, muscle fibers, fascicles, the entire skeletal muscle