ANAT100 - MSK

Composition on muscles

bundles of muscle fibers called fascicles

Fascicles

bundles of elongated striated muscle cells

Epimysium

surrounds entire muscle

perimysium

surrounds individual fascicles

endomysium

surrounds individual muscle fibers (dense irregular tissue)

tendon

all connective tissue layers (epimysium, perimysium, endomysium) extend beyond the muscle belly to form tendon

Aponeruosis

flat sheet of connective tissue that attaches flat muscle to bone or muscle to muscle (eg. external oblique)

muscle fiber

multinucleated cell

Sacrolemma

cell membrane

sacroplasm

most of volume occupied by myofibrils. Also contain glycogen and myoglobin

Myobirils

long chain of sarcomeres

Sarcomere

region between adjacent z-discs, composed of overlapping thick and thin filaments.

A band

dark striation in filaments

I band

thin striations in filaments

Sarcomere shortening

thick filaments move in towards the z-line to contract. There is no inbetween, it's all or nothing.

motor unit

neuron and the muscle fibers it stimulates

muscle's mass location

proximal to the joint

Muscle origin

end of the muscle attached to an immovable bone

Muscle Insertion

the end of the muscle attached to the movable bone

prime mover

has major responsibility for movement

antagonist

opposes the prime mover

synergist

stabilizing muscle

fixator

stabilizes the origin of a muscle