Module 8 - Muscle Length & Joint Geometry Flashcards
What Factors influence Force Production?
- Muscle Architecture
- Neural Factors
- Force-length relationship
- Force-velocity Relationship
What parts of the muscle architecture influence force production?
- Muscle Fiber Arrangement
- PCSA
- Muscle Fiber Types
What neural factors influence force production?
- Firing rate of motor units
- Orderly Recruitment of motor units
What part of the force-length relationship influences force production?
- Active and Passive Components
How does the force-velocity relationship influence force production?
- High velocity generates low force (for concentric actions)
What is crucial for understanding force production?
Concepts
- Moment arm
- Moment of Force (torque)
Why are the concepts of moment arm and moment of force important for understanding force production?
- Bones constrained to rotate about a joint axis
- Linear Actuator (muscle) transmits force to the angular musculoskeletal system
How do muscles generate and transmit force?
- Via Tendons to the bones
What needs to be known to estimate muscle length if we know joint geometry?
- Distances between muscle insertion and centre of rotation
- Joint angle
How can you measure joint angle?
- Motion capture
How can you estimate distance between muscle insertion and joint centre of rotation?
- MRI
What mathematical concept is used to estimate muscle length using the distance between muscle insertion and centre of rotation, and joint angle?
- Law of Cosines
What is the law of cosines?
c^2 = a^2 + b^2 − 2ab*cos(y)
y = joint angle
How does muscle length change?
- As a function of joint angle
How does angular velocity affect joint geometry?
- Faster angular velocity = quicker shortening times and angle change
