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
what does a plane joint do? give example
one surface moves over another surface
tarsal bones, carpal bones
lack of definitive axis, sliding and rotation, tension restricts motion
what does an ellipsoid joint do? give example
flexion/extension, abd/add
radiocarpal
convex and concave surface elongated. spin cannot occur
what is the histologic consistency of dense connective tissues? (ligaments, capsule, tendon)
tightly packed type I collagen
limited blood supply
low-mod proteoglycan and elastin
what is the histologic consistency of articular cartilage? (hyaline cartilage)
high type II collagen fibers
high proteoglycan
no perichondrium - allows opposing surfaces to form but no blood vessels
what is the histologic consistency of fibrocartilage? (menisci, labra, discs)
high multidirectional type I collagen fibers
mod proteoglycan
osteoblasts vs osteoclasts
osteoblasts - build bone
osteoclasts - remove, resorb bone
true or false. bones is dynamic meaning good for remodeling and constantly altering its shape, density, strength and response to external forces
true
what happens when immobilization occurs?
changes in structure and function of connective tissues
mechanical strength is reduced
how fast does immobilization affect the body?
happens within days but recovery is slow and sometimes incomplete
what is happening when periarticular connective tissue and bone age?
aging is accompanied by a slowing of the rate of fibrous proteins and proteoglycan replacement and repair in all periarticular tissues and bones - happens because of many external factors
what can help the aging of tissue and bone?
physical activity and training
what are 3 elements ALWAYS found in synovial joints? - including pathologies that affect the structures
- synovial membrane - inflammation and enlarged synovial membrane may cause pain, reduced motion and destruction of articular cartilage (if chronic)
- articular cartilage - degeneration reduces the ability of the cartilage to protect subchondral bone from damaging forces
- capsule - partial tears or overdistension can reduce joint stability
– external layer: fibrous, dense, support
– internal layer: synovial membrane 3-10 cells thick
what are all 7 elements ALWAYS found in synovial joints?
- articular cartilage
- blood vessels
- ligaments
- synovial membrane
- sensory nerves
- capsular ligaments
- joint capsule
what 5 elements are SOMETIMES found in synovial joint?
- intra-articular discs or menisci
- peripheral labrum
- fat pads
- bursa
- synovial plicae
what are the 4 periarticular connective tissues?
- connective tissues
- muscle (skeletal, cardiac, smooth)
- nerve
- epithelium
what are the two fibrous proteins that compromise all connective tissues in the body?
- collagen
- type I = thick fibers (ligaments, tendons, capsule)
- type II = thinner fibers (hyaline cartilage) - elastin - tissue extensibility/recoil
- skin, tendons, lungs, lining of arteries
what are Sharpey’s fibers?
collagen fibers extending deep into bone material
what is the function of dense connective tissue?
resists tension
ligaments and joint capsules protect and bind joint
tendons transfer forces between muscle and bone
what is the function of articular cartilage?
distributes and absorbs joint forces (compression and shear)
reduces joint friction
what is the function of fibrocartilage?
supports and stabilizes joints
dissipates loads across multiple planes
guides complex arthrokinematics
how does cartilage get nutrition?
via synovial fluid –> milking action (intermitent joint loading)
large proteoglycan complexes are trapped. they attract water but repel each other. this stiffness and hydrophilic nature helps proteoglycans protect cells from outside sources –> increases capacity for loads
what is joint proprioception?
ability to sense static or dynamic position of a limb. sensory fibers embedded in skin, muscles, periarticular connective tissues
what are mechanoreceptors?
afferent joint receptors - sensation and proprioception
where are type I receptors located?
fibrous joint capsule, esp. superficial layers
what is the function of type I receptors?
provide feedback regarding static joint position and joint acceleration.
sensitive to tensile forces
where are type II receptors found?
fibrous joint capsule, esp. deep layers and articular fat pads
what is the function of type II receptors?
provide feedback regarding joint acceleration. sensitive to compressive forces
where are type III receptors located?
ligaments
what is the function of type III receptors?
active at the extremes of joint motion
provide feedback regarding tissue deformation
where are type IV receptors located?
capsular ligaments, fat pads, intramuscular connective tissues
what is the function of type IV receptors?
signal presence of noxious, chemical, mechanical and inflammatory stimuli
what is wolff’s law?
tension and compression cycles create a small electrical potential that stimulates bone deposition and increased density at points of stress
how do bone spurs form?
from increased spinal stresses (discal or instability)
what is the structural subunit of bone?
osteon or Haversian canal
why can bone withstand tremendous compressive loads?
long axis of shaft
