1. (Generalizations, therefore there can be exceptions)
Muscle Principles
(Generalizations, therefore there can be exceptions)

2. Muscles have at least 2 points of attachment– an origin and an insertion

3. Muscles attach to bones either by tendons or fleshy connections

4. Muscles must cross at least 1 joint to create movement (Exception: the face)

5. Muscles shorten as they contract
(Exception: isometric contractions where muscle is activated but does not lengthen or shorten…stays the same. Example: holding a box in front of you)

6. Muscles only pull

7. Muscles only work
in antagonist pairs

8. Muscle fibers or
tendons ultimately go in the direction that they pull

9. Flexors are on the ventral surface and extensors are on the dorsal surface

10. Muscles shape the bones

11. Muscles that cross one joint are deep and are for power and stability
Muscles that cross many joints are superficial and are for speed and agility

13. Muscles for speed have parallel fibers (down hill), and muscles for power have fibers that run diagonally at an angle to the length (snow plow)

15. Small muscles create subtle movements, big muscles create gross movements

16. Muscles are named for a variety of reasons and the names help to remember something about each muscle
Size, shape, direction of fiber, function/action, origin/insertion, combination