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smallest functional unit of muscle tissue


a series of sarcomeres

muscle fiber

muscle tissue cell


a bundle of muscle fibers

thick filaments


thin filaments



protein that connects m line to z line

titin maintains

the position of the mysoin; prevents the sarcomere from being pulled apart;main component of muscle tone

muscle fiber types

type I, type IIA, type IIB

type I

slow twitch, red,built for endurance

type IIA

fast twitch, red, can be trained

type IIB

fast twitch, white, built for power

muscle spindles

lie parallel to muscle fibers, detect changes in muscle length and speed.

specialized muscle receptors

responsible for deep tendon reflexes


main muscle used to produce movement


muscles that oppose the agonist


muscles that assist the action of the agonist


muscles that stabilize proximally to allow the agonist to worki distally

fiber type is determined by


every muscle in the body contains

all three fiber types

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