Muscular System

• Excitability
• Contractility
• Extensibility
• Elasticity
• - Viscoelasticity

The ability to react to stimuli

The ability to develop tension

The ability to be stretched

The ability to return to normal after being stretched or shortened

Enables muscle to stretch greater over greater time

The more hamstring flexibility you have, the further you can go (rubberband example)

• Impart motion
• Maintain posture
• Generate heat

The ability of a muscle or group of muscle to produce a force in one maximum effort

• Smooth
• Skeletal
• Cardiac

Non-striated and involuntary; found in the walls of organs

Striated and voluntary; stimulated by the somatic nervous system; moves bones; always pull and never push

Striated and involuntary; found in the walls of the heart

• Isometric
• Concentric (isotonic)
• Eccentric (isotonic)

Muscle contracts but does not change length (pushing hands together)

Shortening contraction

Lengthening contraction

"Myofibers" = muscle cells

The functional unit of a muscle; consists of a motor neuron and the muscle fibers (anywhere from 2-100s) it controls

Connective tissue covering individual muscle fibers

Connective tissue that covers a group of fibers (fiber bundles)

The covering of the entire muscle

Attaches to bone

Sheet-like tendon

Usually the proximal end of the muscle, which remains fixed during muscular contraction

Usually the distal end of a muscle, which is movable

The meeting of a muscle and its tendon

• Fusiform
• Unipenate
• Bipenate
• Multipenate

Long slender muscle; fibers run parallel to muscle belly; example: sartorius

Half feather appearance (based on the arrangement of the fascicles); example: flexor pollicis longus

Whole feather appearance (based on the arrangement of the fascicles); example: gastrocnemius and biceps brachii

Multiple feather structures; example: deltoid

• Agonist
• Antagonist
• Synergist
• Fixators

Prime mover; primarily responsible for movement; muscle MOST involved

Resist prime mover's action and cause movement in the opposite direction of the prime mover; control speed, protect joint

Assist prime mover; prevent unwanted movement in intermediate joints; example: wrist flexors/extensors stabilize the wrist while ti digit flexors/extensors work

Stabilize to prevent unwanted movement (if you're doing elbow flexion, the deltoid stabilizes to prevent shoulder flexion); contract isometrically in order to stabilize