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