midterm Flashcards
EMG can be used for diagnosis of
- Tingling
- Numbness
- Weakness
- Cramping
EMG can be used to determine
- Nerve dysfunction
- Muscle dysfunction
- Neuromuscular junction issues
Surface Electromyography
-electrodes stuck on skin
- Electrode placement over muscle belly, easy to apply and comes in various sizes
- Disadvantages: subcutaneous fat, skin oil, hair
Indwelling Electromyography
-electrode on end of needle
- Can get recordings of specific or deeper muscles
- Disadvantages: painful, invasive, not a representation of a whole muscle
Fascicle organization
Two types – pennate and parallel
Parallel
allows for greater changes in length
- Have fibers running longitudinal axis with interconnections
- Enable greater shortening of the entire muscle than pennate = larger ROM
Pennate
- good to produce more force
- Rotate about tendon attachment when contracting, causes angle to increase
- Higher fiber per unit of muscle volume
what can affect the signal?
Intrinsic
- Number of active MU
- Fiber composition
- Blood flow
- Fiber diameter
- Distance between fibers and electrodes
what can affect the signal?
Extrinsic
- Distance between electrodes
- Placement of electrodes
- Skin preparation
- Perspiration
- Temperature
Concentric contraction
A muscle contraction in which the muscle torque is greater then the load torque and as a consequence the active muscle is shortend
Eccentric Contraction
A muscle contraction in which the load torque is greater then the muscle torque and as a consequence the active muscle is legthned
Isometric
A muscle contraction in which the load torque is equal to the muscle torque and as a consequence the whole muscle length does not change
EMG:
signal your muscle produces when it contracts
Crossbridge
is the fact that myosin must adhere to actin
Tropomyosin
is lying on top of those magnets acts as barrier for actin and myosin
-blocks muscle contraction
-blocks active sites on actin filaments
Troponin
key hole deciding weather tropomyosin is on or off actin
-facilitates muscle contraction
-regulates calcium binding to actin filaments
contraction cycle
Contraction cycle continues if ATP is available and Ca2+ level in sarcoplasm is high
1. Myosin heads hydrolyze ATP and become reoriented and energized 2. Myosin heads bind to actin, forming crossbridges 3. Myosin crossbridges rotate towards center of sarcomere (power stroke) 4. As myosin heads bind ATP, the crossbridges detach from actin
Kinetics
measurements of forces on a body
Kinematics
measurement of the motion and position of a body
-the description of the motion of a body (or segment) in terms of position, displacement, velocity, and acceleration, with out reference to the forces causing the motion
Electromyography
measurement of action potentials along muscle fibres
-provides info regarding timing and level of muscle activation.
Segment
A predefined portion of the whole object
Position
-the location of an object relative to some reference
Displacement
A vector quantity representing in magnitude and direction the difference in position of two points usually measured in meters. smallest distance between two places
Velocity
the rate of change in position with respect to time. usually measured in meters per second.
in order to increase velocity must accelerate
-change in velocity on graph is a change in direction
Acceleration
-the rate of change of velocity, expressed in meters per second per second
-change in acceleration on graph is a change in speed
Spatial-spatial graph
x and y plane are denoting a plane in space
spatiotemporal
x axis is time
y axis position or velocity or force
Vectors
-need a coordinate system to give direction
-can be broken into x and y components
-useful to add together to determine resultant forces
-adding vectors is done through tail to nose method
Steps to Adding Vectors
1 Define coordination
2 Resolve each force
3 Add components
4 calculate magnitude
5 Calculate Angle
Solve for Fy and Fx Vector component
Fy=Fsintheta
Fx=Fcostheta
Vector Resultant equation (magnitude for adding vectors)
F^2= Fx^2+Fy^2
Adding Vector components
FRx= F1x+F2x
FRy= F1y+F2y
