biomechanics exam 2- human skeletal muscles

overactive muscles

muscles engaged in motions when they shouldn't be

under active muscles

Muscles NOT engaged enough in motions where they should

muscle spindles fade

what happens when we hold a stretch in PNF stretching

GTOs activate

what happens when you contract muscle being stretched in PNF stretching

reciprocal inhibition

the relaxation of muscles on one side of a joint to accommodate contraction on the other side

GTOs

detect change in TENSION

-excitatory to antagonist

-inhibitory to agonist (autogenic inhibition)

-prevents excessive tension

proprioceptors

Sensory receptors, located in the muscles and joints, that provide information about body position and movement.

muscle imbalance

altered reciprocal inhibition problem

-eccentric phase of stretch shortening cycle

stretch of the agonist muscle, increase of stored elastic energy, stimulates muscle spindles

amortization phase of stretch shortening cycle

the pause, SA/ME singals

concentric phase of stretch shortening cycle

shortening of agonist, recoil effect, increase of force bc of stretch reflex

muscle spindles

STRETCH receptors in muscle belly

-excitatory to agonist

-inhibitory to antagonist

-prevent over stretching

motor unit

A motor neuron and all of the muscle fibers it innervates

increase in force production

-generate more motor units

-generate type llx

-generate synchronization of motor units

actin +myosin

contractile component

tendon

series elastic component

-recoil affect

Epi, Peri, and Endomysium

parallel elastic component

-no recoil affect

dynamic

what type of stretch is better for warm ups

static stretching

can temporarily decrease elastic recoil of SEC

parallel muscle fibers

muscles with greater excursion (dif between lengthened and shorten position)

-greater ROM

-disadvantage in force prod.

pennate muscle fibers

-arranged obliquely

-greater CSA

-greater force prod.

-disadvantage in ROM

eccentric contraction

what contraction produces the most force/ most likely to get injured doing

direct

relationship between eccentric velocity and force

inverse

relationship between concentric velocity and force

concentric

which contraction produces the least amount of force

bi-articulate muscles advantages

the movements are able to keep the muscle the same length

90 degrees

greatest mechanical advantage, bad position for tension production in a bicep curl

resting muscle length

maximum force is produced because of the availability of binding sites

stretched and shortened muscles

not ideal for force production because myosin can't bind to actin

active insufficiency

When a muscle cannot shorten anymore because both joints are contracting

passive insufficiency

When a muscle cannot stretch anymore

-length tension relationship

length-tension relationship

the amount of tension generated by a muscle depends on how stretched or shortened it was before it was stimulated

open chain movement

Involves the distal limb moving freely in space.

closed chain movement

distal end is fixed

force coupling

When two or more forces pull in different directions to contribute to a specific movement. (bone rotation)

internal rotation

line of pull is inferior/medial to vertical axis

external rotation

line of pull is posterior/lateral to vertical axis

abduction

line of pull is superior/lateral to A+P axis

Adduction

line of pull is inferior/medial to A+P axis

flexion

line of pull is anterior to M-L axis

extension

line of pull is posterior to M-L axis

insertion to origin

line of pull

agonist

causes mvmt concentrically

synergist

helps agonist

antagonist

controlling movement (opposite mvmt)

-eccentrically)

stabilizer

contracts isometrically to keep bone in place

neutralizer

isometrically prevents joint action from happening

isometric

no movement

concentric

muscle shortens (positive work)

eccentirc

muscle lengthens (negative work)

excitability

ability to respond to stimuli

conductivity

ability to spread an electrical current

contractility

ability to shorten

Extensibility

ability to stretch

Elasticity

The ability of a material to bounce back after being disturbed

crossbridge being formed

when does muscle force begin

neuromuscualr junction

Connection between motor neuron axon and muscle fiber.

all-or-none principle

you will recruit all muscle fibers or none

-no mixed units

motor unit

A functional unit made up of an alpha motor neuron and all the muscle fibers it innervates.

normal resting length

length of a muscle when it is unstimulated

Type 1 muscle fibers

Aerobic, Red, Slow twitch, smaller fibers, extensive blood supply, large amt of mitochondria (ex: marathon, swimming)

type 2x muscle fibers

Fast-twitch, larger in size, anaerobic, white, (ex: sprinters)

passive tension

stretching of a muscle

active tension

contraction

muscle tone

slight tension at rest

Troponin

what does calcium bind to

Tropomyosin

what does troponin sit on

actin

what does tropomyosin sit on

actin

myosin binds to...

myosin

thick filament

actin

thin filaments

Epimysium

surrounds entire muscle

Perimysium

surrounds fascicles

Endomysium

Surrounds individual muscle fibers