Kinesology Exam 3

What must happen for movement to occur?

Muscles Must:

1. Be able to contract

2. Be attached to bone or bones

3. Cross an articulation

______ occurs at joints, but ______ perform the ovement

Movement; muscles (location determines function)

Characteristics of Muscle

1. Excitability

2. Contractility

3. Extensibility

4. Elasticity

Excitability

The ability to receive and respond to various stimuli (MUST RECEIVE & RESPOND unless gravity or person)

Stimulus

Anything that incites or excites an organism to function or become active

Contractility

Once a stimulus is received, the muscle has the ability to produce tension at both ends and shorten

Extensibility

Once a stimulus is received, the ability to lengthen in an active or passive state

• t-3 or t-4 is spinal cord severance

• ACTIVE or PASSIVE

Elasticity

When a muscle has been shortened (concentric) or lengthened (eccentric), the ability to return to normal or resting length/shape without damage

• Stay within AA if not a stain will occur

• Stretching increases AA

What do all of the characteristics of muscle have in common?

RECEIVE & RESPOND

Muscular Attachments

Known historically as origin and insertion but there has been confusion because they can change; now fall into 2 categories

Attachments Categories for Origins & Insertions:

1. Extremities

• Proximal

• Distal

2. Head, Neck, Trunk

• Superior

• Inferior

3. Horizontal Movement

• Medial

• Lateral

9 Ways Muscles Are Named

1. Shape

2. Number of heads

3. Region

4. Attachment

5. Size

6. Orientation of Fibers

7. Relative Position

8. Function

9. Multiple

Shape

Trapezius, rhomboid, deltoid

Number of Heads

Biceps, triceps, quadriceps

Region

Brachial, pectoralis, indicis, pollicis, abdominis

Attachment

Femora’s, ulnaris, radialis, tibialis

Size

Maximus, minimus, breves (short), longus, major, minor

Orientation of Fibers

Rectus, oblique, transversus

Relative Position

Lateralis, intermedius, profundis, superficialis

Function

Flexors, abductors, medial rotators, pronators, extensors

Multiple

Biceps femoris, adductor longus, pronator quadratus

Contraction

When the muscle fibers:

1. Generate tension within themselves at both ends

2. Muscle shortens

3. Muscle lengthens

4. Muscle stays the same

MUST RECEIVE & RESPOND

Types of Contractions

1. Concentric/Shortening

2. Eccentric/Lengthening

3. Isometric or Static

4. Isokinetic

5. Isotonic

Concentric Contraction

Shortening; overcomes 3- weight of the segment, additional weight, and gravity

Eccentric Contraction

Lengthening; does not overcome

Isometric Contraction

Staic: iso=equal & metric=length

Isokinetic Contraction

At equal speed

Isotonic Contraction

At equal speed

Machine that measure strength & power for ISOKINETIC

Biodex

Machine that measure strength & power for ISOTONIC

Cable Machine

Machine that measures ROM

Goinometer

4 Roles of Muscles

1. Movers/Agonist

2. Antagonist

3. Stabilizers, Fixators, & Supporters

4. Neutralizers

Movers/Agonist

1. Prime Movers

2. Assisted Movers

3. Emergency Movers

Prime Movers

Most responsible for movement

Assisted Movers

Helps in certain situations

Emergency Movers

Super human and life changing situations (ex: client injured during an emergency or weird way)

Antagonist

Muscle on the opposite side of the agonist

Stabilizers, Fixators, & Supporters (SSS vs. MGM)

Contract statically (isometrically) to steady & support against other muscles, gravity, momentum (MOST USED/LARGEST GROUP)

Neutralizers

Neutralize/cancel an unwanted movement of an agonist (any muscle can do this that can do more than one thing)

Biarticular Muscle

Acts and crosses two joints

What is the influence of gravity?

A lot of muscles’ movement roles depend/may be reserved on whether or not it is WITH or AGAINST gravity

Example of Gravity Reversing Roles:

• Bicep Curl: flexors control extension

• Squat: extensors control flexion

Line of Pull

This is what determines the movement a muscle can perform

What determines the movement a muscle can perform?

1. Type of joint the muscle spans (hinge, pivot, uniaxial, triaxial, etc.)

2. Muscle’s relationship to that joint (posterior, superior, lateral, etc.)

Methods of Studying Muscles

1. EMG

2. Conjecture & Reasoning

3. Dissection (cadaver)

4. Inspection & Palptation

5. Models

6. Muscle Stimulation (EMS)

7. Imaging

EMG

Electromyography is the most common way to study muscle; measured in millivolts/intensity in time, like an EKG measuring and graphs electrical activity of muscles

Conjecture & Reasoning

Thinking through, logic

Inspection & Palpatation

Sight and touch which is good when there is no access to machines

Models

Simple to complex; ex. stick figures, popsicle sticks, & computers

Muscle Stimulation (EMS)

Electrodes

Imaging

• MRI

• CT

• PET scan

• Tomography

MRI

Magnetic resonance imaging

CT

Computed tomography

PET Scan

Positron emission tomography

Tomography

A diagnostic technique that produce a film of detailed cross section of tissue at a predetermined depth

Type I

Slow-twitch fibers, slow oxidative (SO), oxidative (ATP), endurance/long term, darker (red) from more O2

Type II Fibers

Fast-twitch; two types

Type IIa

Intermediate fibers, some traits of oxidative and some of glycolytic, fast oxidative glycolytic (FOG), grey

Type IIx Fibers

Fast, glycolytic (FG), speed, sprinting fast, short bursts, white with less capillaries

What are most people muscle fibers %?

SO: 50%

FOG: 25%

FG: 25%

• Vary among people and various muscles

• May be 2-10% difference by ST & ET

10 Ways Muscle Fiber Types Vary

1. Speed of contraction

2. Strength

3. Color (myoglobin)

4. Blood Supply

5. Size (diameter)

6. Mitochondria density

7. Resistance to fatigue

8. Triglyceride use

9. Glycogen use

10. Phosphocreatine use

11. Recruitment

Recruitment

TYPE I (SO) → TYPE IIa (FOG) → TYPE IIx (FG)

How do we know how muscle fibers vary?

muscle biopsy

Muscle Biopsy

I cm incision into muscle and remove a small part of tissue; weighs about 10-110 mg, cleaned, frozen, sliced, and stained

Muscle Fibers

A myocyte which is single muscle cell

• a threadlike fiber 0.5 to 20 inches in length (biceps ~10-12 cm)

• Can shorten to 50% of resting and lengthen to 50% of resting length

Amplitude of Action (AA)

Shortest length to longest

• Going beyond this can cause an injury and that is why stretching is so important

Microarchitecture/Microanatomy

Gross: seen to microscope (unseen, but where movement occurs

Order of Muscle

1. Muscle & Tendon

2. Fasciculus (fasciculi, bundles)

3. Muscle Fiber

4. Myofibrils

Number of Fibers in Muscles

Several thousand to over a million; estimated 100,00 sarcomere/inch of myo fiber

• These fibers diameters range from 10-120 micrometers

3 Functions of Microarchitecture (Muscle Cycle/Contraction)

1. Crossbridgign

2. Sliding Filament Mechanism/Theory

3. Relaxation/Rest

AP

Action potential/stimulus

Sarcomere

Most basic part of contractile tissue

Myosin

Thick filaments, attached to m-line

Actin

Thin filaments, attached to 2-line

Tropomyosin

Inhibitor of crossbridge & relaxation

Troponin

Activator; help stand

Calcium (Ca++)

In sarcoplasm reticulum; stored in bones (so people do not get hypocalcimic)

Acetylcholine

Neurotransmitter (Ach, Achesterase)

Sarcoplasmic Reticulum

Sacro-flesh, reticul-network, stores release, reabsorbs Ca++

ABS

Actin binding sites

ATP

Energy currency of the body (ATPase, energy)

Z-lines

Boarder ends of sarcomere

Z-discs

How actin and myosin attach to the Z-line (we lose these when age = less tension)

M-line

Center of sarcomere, anchor

Crossbridging (4 STEPS)

1. Relaxation/Inhibition

• Tropomyosin has dominance & ABS are covered

2. With stimulation AP & Ach

• Ca++ from the SR, cell is depolarized

3. Ca++ & troponin act together to move Tropomyosin to expose ABS

4. Using energy from ATP (ATPase) on myosin, globular heads of myosin cross the bridge to the ABS on action

Sliding Filament Theory

1. ONCE CROSSBRIDGING HAS OCCURED

2. The myosin head tilts and drags the actin stand toward the center (m-line)

3. Power Stroke=tilting & pulling

4. Pulls on Z-lines and generates force rope

5. Repeated (think of a ratchet style with tension release sequence)

• This shortens or lengthens the sarcomere

  • Sarcomere → myofibril → fiber → fasciculi → muscle → tendon → ALL COMBINATIONS MOVE ARTICULATION

Return To Relaxation

1. Once AP stops, Ca++ goes back into SR

2. Acetylcholinesterase breaks down the Ach, environment back to inhibition

3. Tropomyosin covers ABS & elaxation occurs

4. From Relaxation back to to relaxation

• About 2/3 of all skeletal muscle PRO is myosin

• Each myosin stand usually contains ~200 myosin heads