Kinesiology Exam 1 (PT I) lectures 1-3

What is kinesiology?

study of movement, involves active and passive structures

What is kinematics?

describes bodies in motion without regard to torque and force

What are the two types of motion?

Translational
Rotational

Describe translational movement

All parts of body move parallel to and in the same direction as all other parts

Rectilinear or curvlinear
i.e. head moves in curvlinear fashion while walking

Describe rotational movement

A rigid body (body part) moves in a circular path around some pivot point/axis of rotation

What are the 2 kinematic chains and their significance?

Open Chain
Closed Chain

Open vs. closed chain movement tells us how the joint may move differently, closed-chain movements are more functional and require more muscle force

Open chain

distal segment is not fixed on earth or other immovable object, "distal on proximal"

Examples of open chain activities

Single leg raise, pull up at shoulder complex, kicking a soccer ball

Closed chain

Distal segment is fixed on earth or other immovable object, "proximal on distal"

Examples of closed chain activities

Squat, push up, pull up at elbow

Describe concave vs. convex relationships in knee extension

Femur - convex
Tibia - concave

Tibia on femur--> concave on convex

Concave (CC) roll and slide in the SAME direction

Concave vs convex relationships

Concave (CC) roll and slide in SAME direction

Convex (CV) roll and slide in OPPOSITE directions

Depends on open chain/closed chain and which bone is convex/concave as a result

Osteokinematics

description of the bones relative to the 3 cardinal planes, via anatomical position

How do bones rotate?

Bones rotate about a joint in a plane that is perpendicular to the axis of rotation

Cardal planes and their axis

Sagittal (Z-axis)
Transverse (X-axis)
Frontal (Y-axis)

Axis of rotation for sagittal plane

medial-lateral

Axis of rotation for transverse plane

vertical

Axis of rotation for frontal plane

antero-posterior

What plane does humeral flexion occur in? What axis of rotation?

Sagittal plane about the medial-lateral axis of rotation

What plane does cervical spine rotation occur in? What axis of rotation?

Transverse plane about the vertical axis of rotation

Humeral abduction occurs in what plane? What axis of rotation?

Frontal plane about the antero-posterior axis of rotation

Degrees of freedom

Number of independent movements allowed at a joint, max of 3

Arthrokinematics

description of motion between articular joint surfaces

Roll

Multiple points along one rotating surface make contact with multiple points on another surface

Slide

One point on one surface makes contact with multiple points on another surface

Spin

A single point on one articular surface makes contact with a single point on a another articular surface

What is the typical goniometric procedure?

GAP

goniometry, active ROM, passive ROM

Clinical significance of active ROM before passive?

-Gives us baseline measurement of pt capabilities
-Gives us an idea of limitations or weaknesses
-Avoids eliciting unwanted pain

Goniometry is used to assess..

How much and how well joints move

Biomechanics

The application of mechanical principles to human or animal bodies during movement and at rest-- combines principles of engineering with anatomy and physiology

Kinetics

The effect of forces on an object that produces, arrests, or modifies movement

Forces will produce movement if...

Perpendicular to axis of rotation

Wolff's Law

A bone grows or remodels in response to forces or demands placed upon it

Forces produce strength through _______

tension

Types/impact of forces

-Distraction/tension
-Compression
-Bending
-Shear
-Torsion
-Torque

The knee is a screw hole mechanism, allowing for ____ degrees of freedom

2

Are rolls superior or inferior?

Superior

Are glides superior or inferior?

Inferior

_______________ appear to be abnormal arthrokinematics, whereas joint surfaces spinning or rotating on one another appears as a result of regular, healthy movement

Rolling/sliding

Is the GH joint concave on convex or convex on concave?

Head of humerus (convex) moves in the opposite direction of the glenoid fossa (concave)

Convex on concave

Is the elbow joint concave on convex or convex on concave?

Olecranon fossa (concave) moves in the same direction as the humerus (convex)

Concave on convex

Abduction and adduction occur in the ________ plane about the _____ axis of rotation

Frontal

z

For most joints, IR-ER occurs in the _______ plane about the __________ axis

Transverse

y

What happens if the forces acting upon the body exceed physiological capacity?

Mechanical failure

What are some factors that influence the stress/strain relationship?

Atrophy
Mobility

What does the stress-strain graph represent?

The relationship between connective tissue's stress (tension) on the y-axis and strain (stretch) on the x-axis

What does the non-linear region of the stress-strain graph represent?

Collagen fiber's slack under no tension

Includes slack of passive structures such as titin, connective tissue (epi, peri, endomysium) and tendon

What does the relationship (y/x) on the stress/strain graph denote?

All tissues have some degree of stiffness (tightness is a pathological term regarding high stiffness)

What does the linear area on the stress-strain graph represent?

The elastic zone

Represents tissue's ability to withstand force and return to original resting length

What does the area under the nonlinear portion (to the right) of the stress strain graph represent?

The plastic zone

Represents the point at which tissues will but unable to return to normal length due to extreme strain

When does permanent damage or change occur in tissue?

Once tissue is stressed beyond yield point (transition from elasticity to plasticity)

When does most healthy tissue fail?

At 8-13% beyond pre-stretched length

Viscoelasticity

The stress-strain relationship as a function of time

Creep

Gradual change in tissue shape when subjected to a degree of strain in a slow and sustained manner over a period of time

Examples of creep

Gravity and body weight compressing intervertebral discs throughout the day

Torque

An applied force perpendicular to the axis of rotation from a particular distance (moment arm)

Torque is produced through...

Moment arm multiplied by force

Isometric contraction

Muscle contracts but there is no change in muscle length, internal torque = external torque

Concentric contraction

muscle shortens as it maintains tension, internal torque > external torque

Eccentric contraction

muscle lengthens as it maintains tension, external torque > internal torque

When is an ideal opportunity to use isometric exercises?

Post-operative

Benefits of isometric exercises

-Conditioning passive structures (tendons, collagen, etc)
-No change in muscle length, so less demand from active tissue
-More focus on muscle recruitment within conservative ROM

A muscle's ability to produce movement or force on a joint depends on its..

insertion site

Force couples

Groups of muscles that work together, usually in opposite directions, to produce similar movements

Examples of force couples

Periscapular musculature (upper traps, lower traps, middle trap, rhomboids, serratus anterior)

Synergists

Muscles that work together, usually in the SAME direction, to produce the same movement

Examples of syngergists

Anterior arm musculature (biceps brachii, brachialis, brachioradialis)

Levers are defined by....

Where the fulcrum sits relative to an external force

How are levers arms quantified? Which 2 are they?

By mechanical advantage (MA)
Internal and external

Internal moment arm

Perpendicular distance between fulcrum and effort (muscle)

External moment arm

Perpendicular distance between the fulcrum and load (weight)

First class lever rules

-Fulcrum is in the center
-Follow NO rules in regard to MA --> can be greater than, less than, or equal to 1

Example of first class lever

Cervical spine extensors

Second class lever rules

-Load (EMA) in between the fulcrum and effort (IMA)
-IMA > EMA, MA > 1 (mechanical advantage)
-Relatively small degree of motion, great force production

Example of second class lever

Gastrocnemius

Third class lever rules

-Effort (IMA) is between the fulcrum and the load (EMA)
-IMA < EMA, MA < 1 (mechanical disadvantage)
-MOST common lever in musculoskeletal system

Example of third class lever

Biceps brachii

What is mechanical advantage equal to?

-Internal moment arm (muscle/effort) divided by the external moment arm (weight)
- MA=IMA/EMA

Static equilibrium for force analysis

IMA x MF = EMA x EF

Work is...

A product of force and distance (or IMA and distance)

Trade-offs of mechanical advantage

-Increased ROM
-Muscles producing great forces over a short distance
-Generating high forces with high stress to joints (resulting in arthritis and/or wear and tear)

Internal forces

produced from structures within the body (active [muscle] or passive [periarticular CT, ligaments, joint capsules])

External forces

Produced from structures outside of body (gravity, luggage, weights, physical contact)

Definition of Torque

-A vector quantity
-A rotary equivalent of force

Forces ________ produce torque when it acts through an axis (0 distance)

Cannot

Equilibrium is reached when....

Sum of all torques equal zero

Definition of Power

Rate of work

Newton's First law

-Law of inertia
-Body remains at rest unless an external force acts upon it

In static equilibrium, linear and rotational velocities...

Are equal to zero

In dynamic equilibrium, linear and rotation velocities...

Are constant

Inertia is..

Directly proportional to the mass of an object (more mass, more inertia)

Center of mass (COM)

- the point at which body's mass is evenly distributed (sits anterior to S2)
-Every body segment has its own COM

Center of gravity (COG)

The point at which effects of gravity are balanced (usually around S2)

Will running with a good bend in the knee increase or decrease the moment arm?

Decreases moment arm

How is the moment arm related to acceleration?

Torque = moment arm X acceleration, so acceleration = torque/moment arm

Running with dress shoes vs tennis shoes-- which will increase the moment arm? What happens to acceleration?

Dress shoes, because they are heavier

Acceleration decreases

In amputation, what is typically seen with the moment arm? What happens with acceleration?

-Prostheses are built to be lighter, so they will shorten the moment arm
-Results in an increase in acceleration (mechanical advantage)

Newton's Second Law of Acceleration

-Acceleration is directly proportional to force applied (in same direction as the force)
-Inversely proportional to mass (F=ma)

Angular acceleration

-SAME as linear
-Directly proportional to torque (in the same direction of torque)
-Inversely proportional to mass moment of inertia

Newton's 2nd law states that equilibrium is met when...

the sum of all forces equals zero