Kinesilogy Exam 2

Fascia

Everything in the body has connective tissue in some way

Sheaths and converging that connect within and between structures

More or less continuous throughout the body

Important movement, immune and sensory functions in addition to support/covering

Superficial Fascia

Loosely packed, interwoven collagen and elastic fiber layer under the skin

Deep fascia

Dense fibrous connective tissue surrounding muscles, nerves, tendons, etc

Visceral Fascia

Fibrous netting to support organs within body cavities

Fascia Function #1

Muscular attachment

• not all muscles have tendon outs attachments to bone

• Thoracolumbar fascia: erector spinae, latissimus dorsi, abs

• Infraspinatus fascia: Infraspinatus

• Rectus sheath: abdominal obliques

• Fascia lata and IT tract: gluteus Maximus and tensor fascia latae

Fascia Function #2

Transmission of muscular force

• 25-30% of muscle force expressed laterally (not just longitudinally through tendons)

• Epi/peri/endomysium direct these lateral forces into the tendons for movement application

Fascia Function #3

Proprioception

• contains proprioceptors and mechanoreceptors

Fascial Function #4

Pain signaling

• nociceptive bodies and free nerve endings

Fascial Orientation

Normal, youthful, healthy fascia are in a lattice shape. Organized in a uni-directional way

Old, unhealthy fascia are unorganized and multi-directional

Fascial Lines

They dont have a beginning or end, continuous throughout body

11 Fascial lines- 7 primary lines, 4 secondary

Fasciae act like a transmission belt between two adjacent joints and also between synergic muscle groups

Fascial Dysfunction

Normally free-moving connective tissue

Chronic (improper) loading leads to the tissue being “locked”

• can be locked in a shortened or lengthened position

Dense Connective Tissue

Primarily composed of tightly packed collagen fibers that provide support and protection to bones, muscle and other ogans (skin)

Most of the non-muscular “soft” tissue surrounding joints

• fibrous layer of joint capsule (external)

• Ligaments

• Tendons

Regular Dense connective Tissue

Orderly, parallel, orientation of fibers in ground substance

Ligaments and tendons

Collagen most effective parallel to long axis

• after initial slack is pulled resists motion between bones

Irregular Dense Connective Tissue

Haphazard orientation of collagen fibers within the ground substance

Fibrous layers of joint capsule

Tensile resistant from multiple angles/directions

Ligaments

A type of regular dense connective tissue

Bone to bone

Histologic properties

• MORE irregular arrangement of collagen

• Ability to withstand multidirectional tension

• High levels of elastin

Tendon

A type of regular dense connective tissue

Muscle to bone

Histologic properties

• parallel arrangement of collagen

• Uniaxial tension loading

• Weak in other

• Very little elastin

Davis’s law

Describes how soft tissue (re)models based on imposed demands

• heal/repair in the manner in which they are mechanically stressed

Applies to ligaments, tendons, fascia and muscle

Mechanical Properties of DCT

Tendons and Ligaments are viscoelastic

Tendons: high tensile force resistance, flexibility to bend around joints/bone to change resulting angle of pull

Ligaments: pliant and flexible, allowing for natural movement, highly in extensible

Load-Elongation Curve

1. ToeRegion

• tissue elongates with small load

• Wavy fibers start to align

• Tissue stretches easily

2. Linear (elastic) region

• fibers straighten out completely

• Stiffness rapidly increases

• Response of tissue to further elongation

3. End of liner region

• load value = Plin

• Curve moves to strain axis

• YIELD point

• Energy equals area under curve

• Progressive failure

4. Maximum load

• Pmax

• Ultimate tensile strength

• Complete failure

Hysteresis

Loading and unloading curves

Hysteresis loop

• area between curves

• Energy loss within the tissue

Viscoelastic Properties

Rate-Dependent

• mechanical properties change with loading rates

Increased loading rates cause steeper linear portion

• greater stiffness (young’s modulus)

Cyclic Testing

• curve displaced to the right (greater deformation) with each cycle

• Indicates plastic component

• Nonreformable deformation (and risk) increase

• Failure can occur within physiologic range

Tissue Properties of Muscle

Irritability: responds to stimulation by a chemical neurotransmitter (ACh)

Contractility: ability to shorten (50-70%) usually limited by joint range of motion

Extensibility: ability to stretch or lengthen, corresponds to stretching of the perimysum, epimysium, and fascia

Elasticity: ability to return to normal state (after lengthening)

Skeletal muscle function

Active contractile component develops force

• dependent on neural factors, mechanical factors, fiber types, muscle architecture

Muscle force transmitted through the tendon to bony insertion

• muscle force on bone creates joints torque (moment)

• Affected by muscle force, moment arm and joint position

Basic Structure of Muscle

Muscle > fascicle > fiber > myofibril > sarcomere > proteins

Muscle Organization

Fibers in fascicles run parallel to the fascicle, but fascicles can be arranged in 4 different shapes/catergories in relation to the tendon

• parallel muscles

• Convergent muscles

• Pennate muscles: uni, bi, multipennate

• Circular muscles

Parallel Muscles

Fascicle run parallel to the length of the muscle

Most skeletal muscles are arranged this way

May sub catergories: flat, fusiform, strap, etc

Convergent Muscles

Fascicles spread out like a fan on one end and converge to a single point on the other

Produce less tension than parallel muscles

Independent contraction of fascicles can produce different movements from same muscle (versatility)

Pennate muscles

Fascicle are angled relative to the tendon

• unipennate- fascicles angled on one side

• Bipennate- tendon in middle with angled fascicles on either/both sides

• Multipennate: branched tendon with fascicles organized around each branch

Produce more tension/force than parallel muscles but short(er) excursion

The Myofibril

• made of many sarcomere lying end to end (like box cars on a train)

• A sarcomere is composed of protein filaments:

• -myosin and actin (contractile)

• -titin and nebulin (structural)

Myosin, the thick filament, is composed of two protein strands, each folded into a globular head at one end

The thin filament, composed of actin, tropomyosin, and troponin, is attached to a z-disk at one end

Structure of the Sarcomere

The sarcomere contains the contractural elements between each pair of Z-disks

An I-Band: light zone

An A-Band: dark zone

an H-Zone: in the middle of the A-band

An M-Line in the middle of the H-Zone

Cross Bridge

6 to 1 filament ratio

Thin Filament Proteins

1. Actin

2. Troponin

3. Tropomyosin

Thick Filament Proteins

1. Myosin

• head region

• Tail region

Alpha Motor Neurons

One alpha motor neuron innervates many muscle fibers, collective called the motor unit

The action potential arrive at thhe dendrites and travels down the axon to the axon terminal

Motor Unit Recruitment Pattern

Size principle of motor unit

• small to large

• Slow to fast

Recruitment Order And why is this the case

Small to large

It requires a smaller neural input to cause a slow motor neuron to reach its threshold and depolarize

Lighter things require smaller motor units

Force Modulation

As additional force is needed, force can be altered by:

• changing firing frequency

• Increasing motor unit recruitment

increase frequency at the onset of a contraction to quickly achieve needed force

Force-Frequency Relationship

Muscle Twitch: force produced from a single electrical signal

Contraction frequency: number for signals per time period (second)

Summation: progressive increase in force with additional signals

• occurs because they have calcium left in the cell from prior signals

Tetanus: fused contraction in which force will not increase

• normal human firing frequency varies, usually around 8-30 Hzz

Skeletal Muscle contraction

Shortening of sarcomere causes shortening of whole muscle

• occurs from both ends towards center

Contractile force produced by sarcomere transmitted to bone

• produces joint motion

Muscle Action: Concentric

Muscle shortens

• lowest force generated

• Uses the most energy

Total use length decreases under tension

• F>R, Force greater than resistance

Muscle Action: Eccentric

total muscle length increases under tension

• R > F

Muscle lengthens

• generates the greatest force; resistive force

• Uses the least amount of energy

• Often causes injury

Muscle Action: Isometric

Total muscle length stays the same under tension

• R=F

Muscle doesn’t change length

• more force than concentric

• Uses less energy than concentric

Muscle Model: Contractile Component (CC)

Active shortening of muscle through actin-myosin structures

Muscle Model: Parallel elastic component (PEC)

Parallel to the contractile element of the muscle

The connective tissue network (endomysium, perimmysium, epimysium) which surround the muscle fibers

Muscle Model: Series Elastic Component (SEC)

In series with contractile component

The tendons

Force- Length Relationship

Active muscle proportional to the # of active crossbridges

Maximal tension occurs at resting length (l0)

• maximal crossbridge formation

Force production altered at extremes of muscle length

Produces greatest force at resting due to optimal cross-bridge formation

Force Length Relationship Sarcomere

resting length

• optimal, max cross bridge formed

Shortened Length

• excessive overlap

• Decreased cross bridge formed

Elongated length

• minimal overlap

• Decreased cross bridge

Force-Velocity Relationship

Typical force velocity curve

• as force increases, velocity decreases

• As velocity increases force decreases

• For connective tissue only

Ex: when lifting a heavy load it moves slower due to needing more force

• lifting a lighter load you dont need as much force, so the speed increases

Electromechanical delay

The delay between neural stimulation of a muscle and the development of muscle tension

The delay is partly due to the time required for the contractile elements of muscle to stretch the series elastic components

Muscle stimulation (activation) begins before force is developed and movement is observed

Time necessary to “take up the slack in the SEC”

Order of Delay

• Stimulus: 1st

• EMG: 2nd

• Force: 3rd

• Joint Angle (movement): 4th

Hill’s Muscle Model/Mechanical Model

Consists of three components

• contractile component

• Parallel elastic component

• Series elastic component

These help us produce force

Series Elastic component

Appears in series with muscle

One at each end

Represents the tendon

Series Elastic component

Appears in series with muscle

One at each end

Represents the tendon

Parallel Elastic Component

In the muscle belly

Represents the fascia

The connective tissue that wraps every layer of muscle

Lenght Tension Relation for whole muscle

when we lengthen muscle passive force contribution ca occur, the fascia and tendon go on tension and can contribute to the force

For whole muscle the greatest force is produced when muscle is lengthened and pushed

Similar to a rubber band, when stretched they can produce more force and rip back. Muscles stretch and accumulate force and rip back.

Young’s Modulus

a mechanical property that measures the stiffness or rigidity of a solid material by finding the ratio of tensile stress to tensile strain

Contractility

The tissue property of a muscle which gives it the ability t shorten and is usually limited by joint range of motion

Passive Tension

Refers to the tension created within a whole muscle as it is stretched past its normal resting length by an external force

Name the 3 components of Hill’s muscle model and identify the tissue structure for each

1. Series elastic- tendons

2. Parallel elastic- muscle fascia

3. Contractile- actin and myosin (sarcomere)

Electromechanical delay is the delay between neural stimulation of a muscle and the development of muscle tension. Why does this occur

The delay is partly due to the time required for the contractile elements of muscles to stretch the series elastic components

What are the 3 catergorries of fascia

Superficial, deep, visceral

Descritpion of the orientation of youthful, active fascia

2 directional lattice

Descritpion of the orientation of youthful, active fascia

2 directional lattice

Chronic or improper loading leads to this Fascial condition

Locked short or locked long

Tendons and ligaments are samples of this catergory of dense connective tissue

Regular DCT

Davis’ law

Describes how soft tissue (re)models based on imposed demands

Viscoelasticity

Property that describes how tissue responds to varying loading rates

Hysteresis loop

Term used to describe the energy loss of a tissue between loading and unloading

Type of muscle action tat requires the most energy (ATP)

Concentric

Type of muscle action where the muscle force produced is less than the resistance force experienced

Eccentric

Type of muscle action where the muscle doesn’t change lenght

Isometric

List the muscle actions in correct order for one full repetition of a squat with a one second pause in the bottom

1. Eccentric

2. Isometric

3. Concentric

Describe the muscle force-velocity relationship

Inverse; as muscle force increases, velocity decreases and vice versa

At what length does the sarcomere produce the most force

At/near resting length

When considering all parts of the muscle, at what length is the greatest force produced

Lengths greater than resting

The ratio of actin to myosin filaments in a sarcomere

6 to 1