1
Q
Define kinetics
A
branch of biomechanics concerned with what causes the body to move the way it does (forces, torques)
2
Q
Define kinematics
A
branch of biomechanics concerned with the study of movement from a geometrical point of view (position, vel, acc)
3
Q
What’s a degree of freedom?
A
Rotation about one of the axis in a local coordinate frame
4
Q
How many DOF are required to specify the configuration of the arm in space?
A
7 DOF
- Shoulder = 3
- Elbow = 2
- Wrist = 2
5
Q
What are the 2 phases of the gait cycle?
A
Stance and swing phase
6
Q
What does the stance phase consist of?
A
Initial contact, mid stance, terminal stance, and preswing
7
Q
What does the swing phase consist of?
A
Pre-swing, initial swing, mid swing, and terminal swing
8
Q
Function of hamstring during gait cycle
A
- Eccentric contraction to brake the swinging foot before heel strike
- Prevent hyperextension of the knee at heel strike
- Dissipate energy during limb deceleration, protecting joints and connective tissues
9
Q
Function of gastrocnemius-soleus during gait cycle
A
- Retard tibial advancement
- Maintain a fixed ankle angle
- Provide “rocker” actions
- Inject propulsive forces during push off
10
Q
Function of quadriceps during gait cycle
A
- Dissipate energy during the cycle
- Stance phase knee flexion
11
Q
Function of gluteus medius/minimum during gait cycle
A
- Abduct thigh at the hip
- Elevate the pelvis
- Prevent pelvic drop
- Decelerate swinging foot
12
Q
Function of tibialis anterior during gait cycle
A
- Prevents rapid plantarflexion of the ankle
- Control foot-floor contact
13
Q
What is measured in clinical gait analysis?
A
- Joint angles
- Ground reaction forces
- Muscle activation patterns
- Joint moments
- Energy consumption
14
Q
What kinds of tech are used to measure gait (for kinetics)
A
- Foot switches,
- Pressure plates
- Pressure insoles
- Force plates
15
Q
What kinds of tech are used to measure gait (for kinematics)
A
- Goniometers
- Electrogoniometers
- Accelerometers
- High speed video
- Passive marker tech using digital video with an IR strobe, multiple cameras, and reflective markers
16
Q
What is forward kinematics?
A
Calculating the position and orientation of an end effector (ie. hand) using the variables of the joints and links connecting to the end effector
17
Q
What is inverse kinematics?
A
Calculation of the variables of the set of joints and linkages given the position and orientation of the end effector
18
Q
What is a spinal cord injury?
A
- Any injury to the spinal cord including vertebral dislocation, fracture, etc
- Can be severed, bruised, or both
- Damage can be complete or incomplete and occurs over several vertebral levels (usually)
19
Q
What are some consequences of SCI?
A
- Paralysis in muscles innervated at or below level of injury
- Loss of blood flow
- Inflammation
- Breakdown of cell structure
- Demyelination
20
Q
How do consequences of SCI evolve over time?
A
- Can have partial return of function
- Resolution in inflammation, tissue healing, and sprouting of motorneurons
21
Q
What muscles are affected by a spinal cord injury?
A
All muscles whose innervation is below the injury site
- Upper extremity muscles: cervical spinal cord
- Lower extremity muscles: thoracic and lumbar spinal cord
22
Q
What are the primary causes of SCI (highest percent first)
A
- Motor vehicle crash
- Acts of violence
- Falls
- Sporting accident
23
Q
Why do most SCI injuries occurs between C4-C7
A
- Most mobile part of the spine making more susceptible to injury
- Less protection from other anatomy
24
Q
What is functional electrical stimulation (FES)?
A
Treatment that uses electrical impulses to activate specific muscles and nerves
25
What are the 3 main benefit areas that FES is used for?
Motor function, sensory function, and therapeutic benefits
26
What are some of the example motor functions that can be restored to individuals with spinal cord injury?
1. Hand grasp
2. Arm movement
3. Trunk posture
4. Walking
5. Bladder Function
6. Breathing/coughing
27
From a physiological perspective, what would limit the application of FES for motor restoration?
- Lower motor neurons must be intact for FES to work because this is where the spinal cord and muscle communicate
- No way to reach the muscle and create movement if the LMNs are not intact
28
What control options are available for a FES user?
- External control unit
- Movement of voluntary limbs/muscles/etc
- Brain computer interfaces
29
What limitations are there on control options for FES users?
Higher injury levels require restoration for more functions but also with fewer options for control
- natural feedback mechanisms would be limited to vision for high SCI
30
What are the variables that must be optimized to restore coordinated function?
1. Stimulation parameters
2. Muscle recruitment parameters
3. Stimulation patterns
31
What variables are associated with stimulation parameters?
1. Pulse width
2. Pulse amplitude
3. Stimulation frequency
32
What variables are associated with muscle recruitment?
1. Threshold
2. Maximum
3. Slope
4. Recruitment order
5. Selectivity
33
Why are stimulation patterns important with respect to restoring coordinated function
Must be coordinated to align with control degrees of freedom
34
What is a brain computer interface?
A direction communication pathway between the brain and an external device
35
What are the major components of a BCI? (order from signal to device)
Signal acquisition --> feature extraction --> pattern recognition --> effector device
36
What is the control dilemma in the context of brain computer interface?
To get a more accurate signal, a more invasive electrode is needed
- Most invasive - higher freq and higher resolution
- Least invasive - low freq and low resolution
37
Strengths of electroencephalography (EEG)
- Non invasive
- Useful for non-invasive brain monitoring during sleep/epilepsy/etc
38
Weaknessess of electroencephalography (EEG)
- Low spatial resolution
- Low bandwidth signal
- Often contaminated with head and scalp muscle activity
39
Strengths of Electrocorticography (ECoG)
- Low-to-mid bandwidth signal - Useful for accurate epileptic brain monitoring
40
Weaknesses of Electrocorticography (ECoG)
- invasive
- low-to-mid spatial resolution
41
Weaknesses of Intracortical (Single-unit recordings)
Invasive
42
Strengths of Intracortical (Single-unit recordings)
- can record individual neurons
- full bandwidth signal
43
What types of information can (possibly) be decoded from brain activity?
1. Movement direction
2. Movement speed
3. Muscle activation
4. Movement goal
5. Discrete on/off events
- Depending on the recorded part of the brain, many different movement parameters may be estimated
44
How do neurons encode information? How does this principle emerge in the context of movement information?
- Information is encoded in the number of action potentials per unit of time (firing rate)
- Neurons have a preferred direction of movement where the firing rate is greatest
- Each neurons preferred direction is scaled by the firing rate
- Scaled vectors are added to get the population vector which predicts the global direction of arm movement
45
What is an evoked potential?
Muscle responses evoked by specific external stimuli that allow understanding of specific neural pathways
46
What are the 2 evoked potentials talked about in class
1. Motor evoked potentials due to TMS
2. Hoffman's reflex
47
What are some applications of evoked potentials
1. Post stroke spasticity and hyperreflexia
2. Depression
3. Evalutating musculoskeletal injuries
48
How does transcranial magnetic stimulation work to excite the brain?
1. Paddle/coil of wire connected to a large electric capacitance
2. When triggered, capacitance discharges which produces an intense current
3. Current creates a magnetic field oriented perpendicular to the coil
4. Magnetic field induces electrical eddy current which can stimulate neural tissue
49
How can TMS target specific muscles?
The coil can be placed over specific motor regions to excite specific muscles
50
What is the H-reflex
Like the knee jerk reflex but evoked by electrical stimulation of a mixed peripheral nerve (Contains la sensory fibers and motor efferent fibers)
51
What are the 4 steps that an H-reflex consists of to get a muscle contraction
1. Electrical stimulation applied to peripheral nerve
2. This primarily stimulates la sensory fibers (and motor efferents if intensity is high enough)
3. La afferents travel to spinal cord where they monosynaptically activate alpha motor neuron
4. Alpha motor neuron sends signal back to the muscle, causing a muscle contraction
52
How is the M-wave produced?
Caused by the direct stimulation of motor efferents (bypassing the spinal cord)
53
How is the H-wave produced?
Caused by the reflexive activation of motor neurons via the spinal cord
54
How can H-reflex be used to assess spinal excitability
Look at H-wave
- A bigger amplitude = more excitable
EBME 307
flashcards
Decks in class (9)
# Cards
-
L01. Intro to Muscle and Joint Mechanics24
-
L02. Joint Diseases and Injuries - Arthritis and Joint Replacement23
-
L03. Ligament Structure, Injuries, and Repair29
-
L04. Intro to Amputation and Prosthetic Limbs30
-
L05. Lower Extremity Prostheses22
-
L06. Body Powered Upper Extremity Prostheses13
-
L07. Electromyogram: Mechanisms, Measurement, and Signal Processing22
-
L08. Myoelectric Control of Upper Extremity Prostheses19
-
Exam 254
