Exam 3 Biomechanics
Deformation
A change in dimensions of a body
Fatigue is defined as __________ regardless of the force required in any given situation.
A decrease in the force generating capacity
Plastic
A deformation in which the object does not return to it original dimension
Lubrication
A fluid is both absorbed by the articulating surfaces & placed between them
Bending
A load applied perpendicular to the longitudinal axis of a body causing it to curve
Shear loading
A load that causes one part of a body to move parallel past another part. For example: Cutting paper
Tension
A load that pulls the parts of a body apart
Compression
A load that squeezes the parts of a body together
The time between the eccentric and concentric contractions in the stretch shortening cycle is known as __________.
Amortization phase
Creep
An increase in strain when the stress is held constant for a period of time
Cocontraction is activation of the __________ and __________ simultaneously.
Antagonist and prime mover
A measure of a body's resistance to bending is known as __________.
Area moment of inertia
Fascia
Arranged like sheets. Coverage at the ends of muscle bellies to form tendons.
Ductile
Characterization that can under very large deformations (gum)
Stretch shortening cycle
Concentration action immediately after an eccentric action. Energy stored from eccentric action contributes to the movement during the concentric action
Force {MTC}>Force {EXTERNAL} in which of the following muscle actions?
Concentric
Articular (Hyaline) Cartilage
Covers the articular surfaces of bones 10-13% collagen 60-80%water
Range of motion (rotation) in a joint is usually measured in __________.
Degrees
Which type of strength curve is represented by an exercise in which the MTC becomes weaker as the joint angle becomes greater?
Descending
Muscle architecture
Determines both the force producing capabilities and operating range of a muscle. Refers to how fibers of a muscle are arrange
A characterization of an object that can undergo very large deformations is known as __________.
Ductile
The time between the onset of electrical activity at the muscle and the production of measurable force is known as __________
Electromechanical delay
Anisotropic
Exhibiting different properties when measures in different direction
An object with greater stiffness requires __________ force for the same amount of deformation.
Greater
Viscoelastic
Have both elastic and viscous properties. Model is similar to a rubber band
An increase in the number of muscle fibers is known as __________.
Hyperplasia
Cindy is a client of yours who needs to increase the flexibility (extensibility) of her muscles. How can you use your knowledge of viscoelastic materials to instruct her on proper stretching techniques?
Initial discomfort decreases (stress relaxation) Stretch increases after being held (creep) Repetition decreases stiffness (hysteresis) Stretching slowly decreases stiffness (strain rate dependency)
Sprain
Injury to a ligament that occurs when it is stretch beyond its capacity
Trabecular
Inner layer of bone Less organized and random Also called "spongy" or "cancellous"
Stiffness is the ratio of the change in __________ to the change in __________.
Load, deformation
Osteopenia
Lower than normal bone mineral density
Isometric action
MTC develops a force that is equal to the external force and does not change its length. No displacement, the MTC is doing no work (the energy of the skeletal system remains unchanged during isometric actions)
Concentric Action
MTC develops greater force than the external force and shortens. MTC is doing positive work. Increasing the energy of the skeletal system.
Eccentric action
MTC develops less force than external force and lengthens. MTC os doing negative work. Decreasing the energy of the skeletal system.
Sagittal plane rotation occurs about a/an __________ axis.
Medial-lateral
Fluid film lubrication
Movement increases the amount of fluid between articulating surfaces, thus increasing their separation.
Muscle tendon complex
Muscle can only control movement by transmitting force through passive components (tendons) to the skeletal segments. Muscles can only pull
During a concentric contraction, there is a __________ and __________ relationship between the force and velocity.
Non-linear, inverse
The type of loading that exists when there is a twist around the neutral axis is known as __________.
None of the above
Cortical
Outer layer of bone Solida and dense Also called "compact"
Osteoarthritis
Progressive degeneration of articular cartilage and bone deep to it
Strain energy density
Relative amount of energy stored by the material
The functional unit of a muscle is the __________.
Sarcomere
Osteoporosis
Severe decrease in bone mineral density
Fibrocartilage
Specialized roles (menisci, intervertebral discs)
Bone functions
Storing minerals producing red blood cells rigid framework mechanical levers attachment site for muscles protecting the nervous system and organs
Wear
Surface material is deformed and removed by frictional forces
Mechanical properties
Tell you how a body as a whole responds to a load (bone-ligament-bone)
Material properties
Tell you how the material that makes up the body responds to loading (just bone, ligament, cartilage, etc.)
Yield point
The amount of deformation that marks the transition form elastic to plastic deformations
Toughness
The amount of energy that can be absorbed by a body before failure
Strength
The amount of loading an object can withstand before failure. Also, depends on how failure is defined
Strain
The change in dimension normalized to the original dimensions
Neutral Axis
The line along which there is neither compressive nor tensile loading on a body during loading
The muscle's force vector is broken down into components that are parallel and perpendicular to __________.
The long axis of the bone
Bone mineral density is __________.
The mineral content in an area or volume of bone
Elastic Modulus
The ratio of stress to strain
Compliance
The ratio of the change in deformation to the change in load
Stiffness
The ratio of the charge in load to the change in deformation
Torsion
The type of loading hat exists when there is a twist around the neutral axis.
Stress
The way a force is distributed within a body
Stress relaxation
a decrease in stress when the strain is held constant for a given period of time
Elastic
a defamation in which the object returns to its original dimesions
Acute fracture
a fracture that occurs instantaneously
stress fracture
a fracture that occurs over time
Hysteresis
a loss of energy to heat when unloading after loading
Brittle
characterization that can undergo very small deformations (glass)
Ligaments
connect bone to bone, restrict certain movements, guide certain movements
An increase in strain when the stress is held constant for a period of time is known as
creep
Elastic cartilage
found in external ear, parts of the nose and other places
Boundary lubrication
lubricating fluid prevents direct surface-to-surface contact
Type 1 collagen
not straight, natural crimp or waviness.
Strain rate dependency
when mechanical properties are dependent upon the rate of change of strain