Skeletal Muscle Microanatomy and Body Movements

Deep fascia

Epimysium

Tendon

Skeletal muscle

Artery

Vein

Nerve

Perimysium

Fascicle

Endomysium

Muscle fiber

Muscle

Fascicle

Muscle fiber

Sarcoplasmic reticulum

Triad

T-tubule

Terminal cisternae

Sarcolemma

Myofibrils

Sarcomere

Myofilaments

Nucleus

Sarcoplasm

Mitochondrion

Openings into T-tubules

Muscle fiber

Myofibril

Myofilaments

Myosin molecule

Tail

Heads

Actin binding site

ATP binding site

Myosin heads

11 nm

Thickness of “Thick filament”

Tropomyosin

G-actin

F-actin

Myosin binding site

Troponin

Calcium ion binding site

5-6 nm

Thickness of “Thin filament”

Sarcomere

Z disc

Thick filament

Thin filament

Connectin

M line

H zone

A band

The darker area

I band

The lighter area

Flexion

movement of a body part anterior/posterior to the coronal plane

Extension

Opposite of flexion; increases angle between bone

Hyperextension

Joint extended more than 180 degrees

Lateral Flexion

Trunk of body moving in coronal plane laterally

Abduction

Lateral movement of body part away from midline

Adduction

Medial movement of body part toward midline

Circumduction

Rotation

Bone pivoting on its own longitudinal axis

Opposition

Movement of thumb toward palmar tips of fingers at carpometacarpal joint

Reposition

Opposite of Opposition

Extension

Flexion

Hyperextension

Flexion

Extension

Hyperextension

Extension

Flexion

Flexion

Extension

Abduction

Adduction

Abduction

Adduction

Adduction

Abduction

Abduction

Adduction

Rotation

Lateral rotation

Medial rotation

Lateral rotation

Medial rotation

Pronation

Supination

Depression

Elevation

Protraction

Retraction

Dorsiflexion

Plantar flexion

Eversion

Inversion

Opposition of thumb and little finger

Agonist

muscle that contracts to produce a movement

Antagonist

actions oppose that of the agonist

Synergist

muscle assisting agonist may contribute to tension close to insertion