Chapter 11: Muscular System Flashcards
Origin
Stationary Bone, usually proximal
Insertion
Attachment of muscle’s other tendon to movable bone, usually distal
Belly (Body)
Fleshy portion of a muscle between tendons (origin and insertion)
Actions
Main movements that occur when muscle contracts
Reverse muscle action (RMA)
Actions are reversed in specific actions
Lever system and leverage
Bone acts as a lever (Rigid structure moves along a fixed point)
Muscle acts as a fulcrum (Fixed Pont)
Effort
Causes movement
Force exerted by muscle contraction
Load/resistance
Opposes movement
Weight of body part being moved
Mechanical Advantage
only needs a small amount of force to move the load over a small distance
Mechanical Disadvantage
Needs a large amount of force to move the load
Lever types (3)
- First-class lever
- Second Class Lever
- Third Class Lever
First class lever
scissors and seesaws
- produces either mechanical advantage or disadvantage
- Fulcrum is between Effort and the load
Second class lever
wheelbarrow
1. Always produces a mechanical advantage
- sacrifices speed and Range Of Motion for force
- Load is between fulcrum and the effort
Third class Lever
- produces mechanical disadvantage
- Favors speed and ROM over force
- effort between the fulcrum and the load
Most common in the body
Prime Mover or agonist
Contracts, causes an action
Antagonist
Stretches, yields to Prime mover
Synergists
Aid movement of prime mover, prevent unwanted movement
Fixators
stabilizes origin of prime mover, so it can move more efficiently
Compartment
Group of skeletal muscles, blood vessels and associated nerves have a common function
- eg. upper limbs: Flexor compartment is anterior and extensor compartment is posterior
Classification of Skeletal Muscles
Direction
Size
Shape
Action
of origins
Location
Origin and Insertion
Orbitofrontalis
Frontal Belly: Superficial to frontal bone, raises eyebrow and Scalp anteriorly
Occipital Belly: Posterior part, superficial to occipital bone, Draws scalp posteriorly and