1. Behavioral Properties of the Musculotendinous Unit
1) extensibility: ability to be

2. Behavioral Properties of the Musculotendinous Unit
2) elasticity: ability to return to
parallel elastic component -
series elastic component -

3. Behavioral Properties of the Musculotendinous Unit
3) irritability: ability to
4) ability to develop tension: (the contractile component of muscle function)

4. Behavioral Properties of the Musculotendinous Unit
From a mechanical perspective, the musculotendinous unit behaves as a contractile component (muscle fibers) in parallel with one elastic component (muscle membranes) and in series with another elastic component (tendons).
Parallel Elastic Component
Series Elastic Component
Contractile Component

5. Structural Organization of Skeletal Muscle
How are muscle fibers organized?
parallel fiber arrangement:
pennate fiber arrangement: short fibers attach to

6. Parallel vs pennate

7. Parallel vs Pennate

8. Structural Organization of Skeletal Muscle
Comparison of fiber architecture
Effective force to tendon:
parallel __ pennate
fibers per unit volume:
joint ROM:

9. Structural Organization of Skeletal Muscle
What is a motor unit?
single motor neuron and all fibers it innervates
considered the functional unit of the neuromuscular system
innervation ratio (# of fibers per motor neuron) dictates fine vs gross control

10. Structural Organization of Skeletal Muscle

11. Structural Organization of Skeletal Muscle
Twitch Tension
Time
FT ST
Fast twitch fibers both reach peak tension and relax more quickly than slow twitch fibers.

12. Skeletal Muscle Fiber Characteristics
TYPE IIA
Type I Fast-Twitch Type IIB
Slow-Twitch Oxidative Fast-Twitch
Oxidative
Glycolytic Glycolytic
CHARACTERISTIC
(SO)
(FOG)
(FG)
Contraction Speed
slow
fast
Fatigue rate
intermediate
Diameter
small
large
ATPase concentration
low
high
Mitochondrial
concentration
Glycolytic enzyme

13. Skeletal Muscle Function
How are motor units (MUs) recruited?
slow twitch (ST) fibers are easier to activate than fast twitch (FT) fibers
ST fibers are recruited first
increasing speed, force, or duration (fatigue) of movement involves progressive recruitment of MUs with higher activation thresholds (i.e. FT)

14. Skeletal Muscle Function

15. Skeletal Muscle Function
Muscles apply tension at origin and insertion
Actions of muscles dictated by:

17. Muscle tries to bring attachment points closer

18. Skeletal Muscle Function
What terms are used to describe types of muscle contractions?
concentric:_________, muscle __ resistance
eccentric: _________, muscle __ resistance
isometric: _________, muscle __ resistance

20. Skeletal Muscle Function
What roles are assumed by muscles?
agonist:
antagonist:
stabilizer:
neutralizer:

21. Stabilizing scapula

22. Neutralizing

23. Qualitative anatomical analysis
Divide the activity into phases
Identify joints involved and joint movements
Determine type of contraction
Against gravity (__) or with gravity (__)?
Increasing (__) or decreasing (__) velocity?
Overcoming resistance (__) or giving with resistance (__)?
What muscle(s) primarily active?

24. Posterior Compartment
Hamstring

25. Skeletal Muscle Function: which muscles need to be active?

26. What joint motion? What muscles active and what type of contraction in each example?

27. What phase? What type of contraction?

28. Skeletal Muscle Function
What are characteristics associated with muscles that cross more than one joint?
active insufficiency:
passive insufficiency:

29. Skeletal Muscle Function

30. Factors Affecting Muscular Force Generation
Velocity
Force
(Low resistance, high contraction velocity)
The force-velocity relationship for muscle tissue: When resistance (force) is negligible,

31. Factors Affecting Muscular Force Generation
The force-velocity relationship for muscle tissue: As the load increases,
Velocity
Force
isometric maximum

32. Factors Affecting Muscular Force Generation: length-tension curve

33. Factors Affecting Muscular Force Generation
Tension
Length (% of resting length)
Active Tension
Passive Tension
Total Tension
The length-tension relationship: Tension present in a stretched muscle is the sum of the active tension provided by the muscle fibers and the passive tension provided by the tendons and membranes.

34. Factors Affecting Muscular Force Generation
What is electromechanical delay? (force-time relationship)
time between arrival of a neural stimulus and tension development by the muscle

35. Factors Affecting Muscular Force Generation
Twitch vs tetanus
Temporal vs spatial summation

36. Muscular Strength, Power, and Endurance
How do we measure muscular strength?

37. Muscular Strength, Power, and Endurance
What factors affect muscular strength?
tension-generating capability of the muscle tissue, which is in turn affected by:

38. Muscular Strength, Power, and Endurance
What factors affect muscular strength?
moment arms of the muscles crossing the joint (mechanical advantage), in turn affected by:

40. Muscular Strength, Power, and Endurance
What is muscular power?
the product of muscular force and the velocity of muscle shortening
the rate of torque production at a joint
the product of net torque and angular velocity at a joint

41. Where does peak power occur

42. Muscular Strength, Power, and Endurance
What is muscular endurance?
the ability of muscle to exert tension over a period of time
the opposite of muscle fatigability