Introduction To Muscles

1
Introduction To Muscles

• Antagonistic Pairs
• Origins and Insertions

2
Antagonistic Pairs

• Muscles work in antagonistic pairs.
• This means that they oppose each other in their
  action upon bones of the skeleton.
• Since all muscles move across at least one joint,
  antagonistic pairs move joints in opposite
  directions.

3

• Muscles cannot push on a joint they can only
  pull a joint in one direction.
• For example, the biceps can flex the elbow joint,
  but is unable to extend it. The extensor of the
  elbow is the triceps. Therefore, they oppose
  each other as antagonistic pairs.

4
The Origin

• The origin of any muscle is the bone to which a
  muscle is attached that remains stationary or
  does NOT move.
• For example, the muscle which moves you jawbone
  as you chew ( the masseter) has its origin on the
  cheekbone (the zygomatic).

5
The Insertion

• The insertion of a muscle is the bone to which a
  muscle is attached that moves.
• While the origin of the masseter is the
  zygomatic, the insertion is on the jawbone
  itself, the mandible.
• During contraction, the muscle insertion moves
  toward the origin.