Week 3 Flashcards
Label
Explain
What are the components of muscle structure?
What is the term for the place where the axon terminals innervate the muscle fiber?
neuromuscular junction
(The activation then leads to cross bridge formation which is the connection of the myofilaments in the sarcomere)
What are the muscle fiber types?
Are muscle exclusive to one type of muscle fibers?
no, muscles will have a portion of all muscle fiber types
The ratio differs from one person to another
Label
Explain the sliding filament theory
What are the 4 phases (in order) of the sliding filament process?
1) cross bridge formation (coupling): myosin + actin
2) power stroke (contraction): kinetic energy is realized
3) detachment (uncoupling): myosin + actin disconnect
4) hydrolysis (precharging/recharging): chemical process where water breaks a larger component
Label
Explain the role of ADP in muscle contraction
ADP (Adenosine diphosphate)
- Troponin and Tropomyosin located on the actin filament
- ADP will not form if the alignment of the myosin head is not matched to the actin filament for chemical exchange
Explain the role of ATP in muscle contraction
ATP (Adenosine triphosphate)
- Calcium from motor neuron released to create ATP
- Energy source needed for a muscle contraction
Explain the steps of the muscle action process
Explain the coupling stage of muscle action
Explain the contraction stage of muscle action
Explain the detachment stage of muscle action
Explain the hydrolysis stage of muscle action
Explain the 3 types of muscle action
What initiates muscle contraction after a synapse is received from a nerve?
calcium influx
What fuels the cross-bridge cycle?
ATP hydrolysis
Does increased muscle performance and speed have an effect on fall risk?
yes, they decrease fall risk
List the needed assessments to be considered prior to muscle performance training
What is the criteria and diagnosis aspects of sarcopenia?
How does sarcopenia affect/is affected by other health conditions?
explain the relationship between force/velocity and length/tension
Should one component of training (flexibility, strength,…) be the only focus of a training program?
no, train for speed, strength, power, flexibility, and endurance
List the formula of force and torque
F = M x A
(Force = mass x acceleration)
T = F x Ma
(Torque = force x moment arm)
What information is obtained from a muscle cross-sectional area?
What is PCSA?
ACSA: perpendicular to the longitudinal axis of a muscle
PCSA: perpendicular to the direction pf fibers
What is the formula for power? What are its units?
P = W / change (lapsed) time (measured in watts)
Work is measured in joules
1 Nm = 1 Joule
Explain the difference between work and power
Define prime movers, synergists, and antagonists
What is needed for the antagonist muscle to facilitate motion?
sufficient length
Define active insufficiency and provide an example
Active insufficiency occurs when a multi-joint muscle is too short to generate effective force because it is fully contracted across all the joints it crosses.
Ex: The hamstrings become actively insufficient when you attempt to fully flex the knee while the hip is also extended, as the muscle is maximally shortened and unable to generate additional force.
Define passive insufficiency and provide an example
Passive insufficiency occurs when a multi-joint muscle is too stretched to allow full range of motion across all the joints it spans. In essence, active insufficiency limits muscle force due to excessive shortening, while passive insufficiency restricts joint motion due to excessive lengthening.
Ex: The hamstrings exhibit passive insufficiency when you try to fully flex the hip while the knee is extended, as the muscle is excessively stretched and restricts motion.
Identify this and label what is causing it?
Upper cross syndrome:
Weakness in one muscle and tightness in opposite group of muscles (ex: pecs & rhomboids)
Identify this and label what is causing it?
Lower cross syndrome
Label these force systems
Why type of force system is present here?
Concurrent force system
What type of force system is present here?
Parallel force system
What type of force system is present here?
Parallel force system
Solve for center of mass
Solve for the resultant force
Solve for the biceps force
In a heel raise (talocrural joint), what are the articulating surfaces, what type of motion and POM, and is the movement convex or concave?
In a high five (lifting hand, first row of carpals), what are the articulating surfaces, what type of motion and POM, and is the movement convex or concave?
List the force types
Explain the convex/concave rule
Elbow
What are the general levels of organization when planning treatment?
Explain a bicep curl movement in terms of the lever system
Provide an example of 1st, 2nd, and 3rd lever systems
Define mechanical advantage
Example of MA > 1 (Effort arm > Resistance arm):
Exercise: Calf Raise
The effort arm is the distance from your heel to the ball of your foot (where the toes push off), and the resistance arm is the distance from the heel to the ankle joint (fulcrum).
In this case, the effort arm is longer, allowing the calf muscles to lift your body weight with relatively less effort due to the mechanical advantage.
Why: The longer effort arm gives the calf muscles an advantage, reducing the force required to lift the body weight during the movement.
Example of MA < 1 (Resistance arm > Effort arm):
Exercise: Bicep Curl
The effort arm is the distance from the biceps muscle insertion to the elbow joint (fulcrum), and the resistance arm is the distance from the elbow joint to the dumbbell in your hand.
The resistance arm is much longer than the effort arm, so the biceps must generate significantly more force to lift the dumbbell.
Why: Since the resistance arm is longer, the biceps are at a mechanical disadvantage, requiring more effort to move the weight.
Define EA and RA
Distance (Perpendicular) from the line of force to the axis
to break up scar tissue, do you go to the failure point on the stress/strain curve?
yes
Explain COM and line of gravity
How does the COM and LOG change throughout the movement?
If F=15N calculate T
Define axis and planes of motion, moment arm and torque, COM, and lever system to solve for unknown forces
Do all connective tissue structures have the same stress/strain curve?
no
Define isotropic and give an example
An isotropic material has uniform mechanical properties in all directions, meaning it responds the same way to forces or stresses regardless of the direction of application. In biomechanics, most biological tissues are anisotropic, meaning their mechanical properties differ based on the direction of the load. However, certain synthetic materials, like metals or ceramics in some cases, can be isotropic.
Example: A steel rod is often considered isotropic because it has the same strength and stiffness no matter which direction a force is applied.
Define ductile and brittle fracture. Give an example for each
Brittle Fracture
Brittle fracture occurs when a material breaks suddenly with little to no plastic deformation, typically under rapid stress or at low temperatures. The fracture surface is usually flat and clean, indicating a rapid propagation of cracks. In biomechanics, brittle fractures are common in bone under high impact or in cases of osteoporosis.
Example: A brittle fracture in the femur can occur when an elderly person with osteoporosis falls directly on their side, leading to a clean break with minimal deformation.
Ductile Fracture
Ductile fracture happens when a material undergoes significant plastic deformation before breaking. This process absorbs more energy than brittle fracture and typically results in a rough, fibrous fracture surface. In biomechanics, ductile fractures can occur in softer tissues or in bones under slower, prolonged loading that allows deformation before failure.
Example: A ductile fracture might occur in a young, healthy individual’s bone during a sports injury, where the bone bends significantly before breaking.
What does the stress/strain curve for ligaments/tendons vs bone look like?
Do tendons/ligaments respond well to tensile forces?
Yes
Do bones respond well to tensile forces?
no
What science law might best apply to bone regeneration and forces?
Wolfe’s Law
Bone marrow creates new platelets, stem cells, red, and white blood cells.
How do you apply the Stress/Strain Model in Clinical Practice?
