lecture 2, exam 1 study guide Flashcards
what is an inertial measurement unit (IMU)?
a device that can measure and report specific gravity and angular rate of an object to which it is attached.
what two things does an IMU usually consist of?
- gyroscope: providing a measure angular rate
- accelerometers: providing a measure specific force/acceleration
what is electromyography (EMG)?
technique concerned with the development, recording and analysis of myoelectric signals. these are formed by physiological variations in the state of muscle fiber membranes
what is EMG the study of?
muscle function through inquiry of electrical signal the muscles emanate
kinesiological EMC can be described as
the study of the neuromuscular activation of muscles within postural tasks, functional movements, work conditions and treatment/training regimes
what is a motor unit?
consists of a single alpha motor neuron and all of its innervated muscle fibers
motor units are naturally recruited by their increasing size
this concept allows for smooth force and minimizes development of fatigue by using more fatigue-resistant fibers most often
if a certain threshold level is exceeded within the Na+ influx, the depolarization of the membrane causes what?
an action potential to quickly change from -80 mV to +30 mV
where does the action potential spread?
along the muscle fiber in both directions and inside the muscle fiber through a tubular system
what is the EMG signal based on?
action potentials at the muscle fiber membrane resulting from depolarization and repolarization processes
what does the depolarization-repolarization cycle form?
a depolarization wave or electrical dipole
what is maximum voluntary contraction (MVC)?
measure of muscle strength
maximum strength is defined as the highest voluntary force possible under dynamic concentric, dynamic eccentric or isometric muscle action conditions and is limited by muscle fiber recruitment and frequency of action potentials
where should you not place electrodes?
over motor point regions of the muscle (area with high density of motor endplates)
how should you place electrodes?
in the direction of the muscle fiber
why is the axis of rotation rarely fixed in anatomic joints?
due to rolling and gliding between parts in a hinge
when is the path of evolute longer and more complex?
when opposing joint surfaces are less congruent / greater differences in radii curvature
what is synarthroses?
slight to no motion on combination of fibrous and cartilaginous periarticular tissue
what are two types of synarthroses? give examples
- fibrous joints - stabilized with specialized dense connective tissue
ex: sutures of skull - cartilaginous joints - stabilized by flexible fibrocartilage
ex: pubic symphysis
what is diarthroses? give example
moderate to extensive motion - majority of joints aka synovial joints
ex: glenohumeral joint, knee, ankle
what does a hinge joint do? give example
flexion/extension - one axis
elbow joint
what does ball and socket joint do? give example
flexion/extension, abd/add, circumduction
shoulder, hip
spin occurs. motion in 3 planes
what does a pivot joint do? give example
rotation - produces spin
atlas-axis, humeralradioal joint
what does a condyloid joint do? give example
flexion/extension, abd/add, circumduction
wrist joint
2 DOF - like ball and socket except concave member shallow
what does a saddle joint do? give example
flexion/extension, abd/add, circumduction, thumb-finger opposition
thumb
2 planes of motion, limited spin
