Muscle Anatomy 101

Three Types of Connective Tissue:Epimysium, Perimysium, and EndomysiumThree Types of Connective Tissue:Epimysium, Perimysium, and Endomysium

Sectional View of a Muscle Fiber

Sectional View of a Muscle Fiber

Sarcomere

• Smallest contractile unit

• Composed of 2 proteins

MyosinActin

• Run from Z-line to Z-line

Interaction Between Actin and Myosin Filaments Interaction Between Actin and Myosin Filaments

Muscle Fibers

Vary in lengthHeld together by connective tissueMulti-nucleated Two types

Type I – high oxidative (slow twitch)Type II – IIa = oxidative-glycolytic (fast twitch)

IIx = high glycolytic (fast twitch)

Muscle Fibers

Hereditary factors vary ratio amongst peopleFiber type cannot be changed

Exception IIa IIx *not 100% positive

Relative Involvement of Muscle Fiber Types in Sport Events

Event Type I Type II

100-m sprint Low High

800-m run High High

Marathon High Low

Olympic weightlifting Low High

Barbell squat High High

Soccer High High

Field hockey High High

Football wide receiver Low High

Football lineman High High

Basketball Low High

Distance cycling High Low

Motor Units

Motor Neuron + Muscle FibersType I or Type IINot located adjacent to each otherSizes vary

Smaller unit = fewer fibers = more precisionLarger unit = more fibers = gross movement

A Motor UnitA Motor Unit

Muscles of the BodyPrimary movers = agonistAssistant movers = synergistsOpposing muscles = antagonists

Muscles of the Body

Origin = closest to core of bodyInsertion = furthest from core of body

Multiple heads provide fine tune function

Spanning over more than one joint allows muscle to serve more than one function