ESS 303 - Biomechanics

The Muscular System

Muscles and Articulations

UniarticulateBiarticulateMultiarticulate

Active Insufficiency: Difficulty in producing full ROM movements in 2(+) joints at the same time

Passive Insufficiency: Difficulty in achieving full ROM stretches in 2(+) joints at the same time

Pennation

Non-pennated Pennated

Muscle Movement Muscle Fiber Orientation

Pennation

Non-pennated Pennated

Pennation

Fusiform Unipennate Bipennate Multipennate

Gre

ater

Mov

emen

tG

reater Force

Contraction Types

Concentric

Eccentric

Isometric

Isotonic

Isokinetic

Static

Fiber Types

Characteristic Fiber Type

Color White White/red RedCapillaries/mm2 Low Intermediate HighMitochondrial volume Low Intermediate High

Histochemistry IIB IIA I

Biochemistry FG FOG SOGlycolytic capacity High High Low0xidative capacity Low Medium/High High

Contractility FT FT STSpeed of contraction Fast Fast SlowSpeed of relaxation Fast Fast SlowFatigability High Moderate/High LowForce capacity High Intermediate Low

Muscle Belly Fasciculus Fiber (Cell)

Epimysium Perimysium Endomysium

Sarcolemma

Sarcoplasm

Nuclei

Gross Structure

The Sarcomere: Z Line to Z Line

A Band

Thick Filament(Myosin)

M LineZ Line Z Line

Thin Filament(Actin)

I Band I Band

H Zone

A-Band

I-Band

I-Band

H-ZoneM-Line

Z-Line

Z-Line

Light MyromyosinS1

S2Heavy

Myromyosin

Length-Tension Relationship

Too Short

Too Long

Length-Tension Relationship

LengthLength

% o

f Max

Ten

sion

% o

f Max

Ten

sion

Force-Velocity Relationship

Velocity

Forc

e

IsometricEccentric Concentric