The Muscular System

1
The Muscular System

• Chapter 10

2
Understanding Muscles

• Pull never push
• Attach to skeleton via tendons or muscles via
  aponeurosis
• Attachment points
• Origin end attaches to a stationary bone
  doesnt move
• Insertion end attaches to a moving bone moves
• Contractions shorten muscles

3
Functional Groups

• Agonist (prime movers)
• Prime responsibility for causing a movement
• Antagonist
• Oppose/reverse movement
• Regulate agonist by adding resistance
• Synergist
• Assist prime mover
• Add extra force or reduce undesirable movement
• Fixators
• Immobilize bone or muscle origin
• Not mutually exclusive

4
Naming Muscles

• Location
• Bone or region associated w/
• E.g. brachii and femoris
• Shape
• E.g. deltoid and trapezius
• Size
• E.g. maximus, minimus, longus
• Action
• E.g. flexor , extensor, supinator

• Direction of fibers fasicles
• E.g. rectus, oblique, transversus
• Number of origins
• E.g. biceps and triceps
• Location of attachment
• Points of origin insertion
• E.g. sternocleidomastoid

5
Fasicle Arrangement

• Determines range of movt power
• Types
• Parallel (fusiform)
• Parallel to long axis
• Pennate
• Short attach obliquely to an insertion tendon
• Uni-, bi-, or multi
• Convergent
• Broad origin converges to an insertion
• Circular
• Concentric rings around external openings
• Contractions close

6
Lever Systems

• A lever (bones) moves on a fulcrum (joints) when
  effort (muscle contraction) moves a load (bone
  and everything else)
• Mechanical advantage (power lever)
• Effort farther from load then fulcrum
• Little effort needed
• Force gained for speed and stability
• E.g. car jack
• Mechanical disadvantage (speed lever)
• Effort nearer load then fulcrum
• Force lost for speed and range
• E.g. shovel

7
Classes of Levers

• First
• Mechanical advantage or disadvantage
• Second
• Uncommon in body
• Always mechanical advantage
• Third
• Most skeletal muscles
• Always mechanical disadvantage

8
Learning Muscles

• Need to know
• Names of major muscles
• Basic functions/actions of muscles
• Table 10.1
• Location
• Studying
• Learn names
• Look for clues in names from existing knowledge
• Draw and or act out
• Identify on models or self