Unit 2 PPT Flashcards
What does a extensibility and elasticity do
Enabled the muscle to be stressed and return the normal length
What are tendons continuations of
Muscles connective tissue and also possess extensibility and elasticity
Contractility
The ability to shorten and produced tension
Muscle functions
Flexibility
Strength
Power
Endurance
What does muscle fiber consist of
Myofibrils held together by sarcolemma that can propagate nerve impulses
How are myofibrils arranged
in parallel formation
what are myofibrils made up of
make appearance
alternating dark and light bands that give muscle fiber their striated appearance
what is myofibrils enclosed in
endomysium
what does actin do when stimulated
slides over myosin
cross bridges
projections of myosin attached to actin
what is a myofibril
any of the elongated contractile threads found in striated muscle cells.
consists of a series of sarcomeres
Concentric contractions
Oppose gravity
Action as indicated
Muscles shortens under tension
eccentric contractions
with gravity
action of opposite muscle group
muscle lengthens under tesion
type I muscle fiber
slow oxidative
type IIa muscle fiber
fast oxidative glycolytic
type IIb muscle fiber
fast glycolytic
type 1 slow twitch
characteristics
smaller, red greater blood supply more myoglobin more resistant to fatigue aerobic
type IIb
characteristics
large, pale less blood supply less myoglobin fatigue easier anaerobic
what do most limb muscles contain
relatively equal distribution of each muscle fiber
what do postural muscles contain more of
slow twitch fibers
sarcomere
contractile unit of skeletal muscle
hyperplasia
increase number of fibers
hypertrophy
fibers get larger in size
Reverse muscle action
Occurs when the distal bone is stabilized and the proximal bone moves
Shows what muscle action will occur
Attachment location
Angle of pull
Number of articulations crossed
What determines movement
Type of joint
Spatial relationships
Classification by movement muscles
flexors, extensors
abductors, adductors
rotators
fusiform
classification by fiber arrangement
muscle fibers parallel to long axis
what can fusiform include
longitudinal, quadrate, trianglur
pennate
classification by fiber arrangement
fibers extend from central tendon
what can pennate include
unipenniform
bipenniform
multipenniform
Longitudinal muscle
long, strap like muscle with fibers in parallel to its axis
example of longitudinal muscle
sartorius
quadrate or quadrilateral
four sided and usually flat
example of quadrate muscle
rhomboids
triangular
fibers radiate from a narrow attachment at one end to a broad attachment at the other end
example of triangular muslce
pectoralis major
fusiform or “spindle”
rounded muscle that tapers at either end
example of fusiform muscle
brachioradialis
unipennate
a series of short, parallel, feather like fibers extends diagonally from the side of a long tendon
example of unipennate muslce
tibialis posterior
bipennate
long central tendon with fibers extending diagonally in pairs from either side of the tendon
example of bipennate muscle
rectus femoris
multipennate
several tendons are present, with fibers running diagonally between them
example of multipennate muslce
middle deltoid
mechanical advantage of fusiform
longer fibers
greater ROM
less force production
mechanical advantage of pennate
shorter fibers
less ROM
greater force production
What is proportional two its physiological cross section
Force a muscle can exert
do broad, thick, longitudinal muscle or thin muscle exert more force
broad, thick, longitudinal muslces
does a pennate muscle or a longitudinal muscle of same thickness exert a greater force
pennate muscle
why does a pennate muscle exert more force than a longitudinal muscle of same thickness
the oblique arrangement of the fiber allows for a larger number of fibers
how much can a muscle shorten to
approximately half its resting length
what long muscles with fibers longitudinally arranged along the long axis do
exert force over a longer distance
what can pennate muscles with their oblique fiber arrangement and short fibers do
exert superior force through only a short range
Types of muscle contractions
Concentric eccentric isometric isotonic isokinetic
concentric
muscle shortens with tension
weight against gravity
eccentric
muscle lengthens with tension
weight with gravity
isometric
occurs
tension but no movement
tension is developed in the muscle without any appreciable change in length
isotonic
constant tension through ROM
equal tension
isokinetic
maximum tension through ROM
equal or same motion
example of isokinetic
cybex, biodex, nautilis
example of isotonic
free weights
what does contract mean literally
draw together
when does muscle contraction occur
whenever muscle fibers generate tension which may occur while the muscle is actually shortening, remaining the same length, or lengthening
when does concentric or shortening contraction occur
when tension by the muscle is sufficient to overcome a resistance and move the body segment
how does eccentric or lengthening contractions occur
when a muscle slowly lengthens as it gives in to an external force that is greater than the contractile force it is exerting
what does a muscle act like during eccentric contraction
a brake
when does isometric contraction occurs under what 2 conditions
antagonistic muscles contract with equal strength
muscle is held against another force
how does isotonic contraction occur
tension remains constant while muscle shortens or lengthens
how does a isokinetic contraction occcur
maximum muscle effort at the same speed
accomodating resistance
movement to gravity
in same direction (downward) opposing gravity (upward) perpendicular to gravity (horizontal)
is horizontal motion affected by gavity
no
what kind of contraction does lifting against gravity require
concentric contraction
what kind of contraction does slowly lowering with gravity require
eccentric contraction
what does forceful downward motion use
agonist muscles in concentric contraction
tension length relationship
optimum length at which a muscle can exert maximum tension is generally slightly longer than the resting length of that muscle
relationship to angle of pull in length tension relationship
physiological advantage
90 degree angle of pull
force velocity relationship concentric contraction
as speed of a muscular contraction increases, the force it is able to exert decreases, as the speed of the contraction decreases, more force can be exerted
what do both muscle and tendon posses
elastic properties
what happens when concentric contraction is preceded by a phase of active stretching
elastic energy stored in the stretch phase is available for use in the contractile phase
movers or agnonists
directly responsible for producing movement
prime movers
large impact on movement
assistant movers
only help when needed
contralateral muscle
antagonist
opposite side of joint
stabilizing muscles
fixators, support
true synergy
joint stabilization
antagonist
two joint muscles
helping synergy
joint movement
agonist
one joint or two joint muslces
synergists
cooperative muscle function
stablizing, fixator and support muscles
neutralizers
prevent undesired action
antagonists
have an effect opposite to that of movers, or agonists
2 things antagonists do
relax to permit movement
act as a brake at completion of movement
cocontraction
simultaneous contraction of movers and antagonists
what do neutralizers and stabilizers need
cocontract to counteract the additional function of a mover
is spurt or shunt muscle more active
spurt
spurt muscle
rotary
shunt muscle
stabilizing
origin 1 > insertion 1
spurt
origin 2 < insertion 2
shunt
pulley action
transmits tension from one muscle to the opposite muscle
2 major advantages of two joint muscle
ability to exert force without losing tension
can exert tension without shortening due to pulley action of tendons
action of bi-articular muscles
muscles that pass over and act on two joints
whether muscles flex joints in the same direction or opposite directions, they are not long enough to permit complete movement in both joints at the same time
resulting tension in one muscle is transmitted to the other
what can bi articular muscles do
continue to exert tension without shortening
concurrent movement
same action occurs at both joints of the two joint muscle
counterconcurrent movement
opposite action occurs at both joints of the two joint muscle
example of concurrent movement
hip extension and knee extension
example of counterconcurrent movement
hip flexion and knee extension
concurrent action
no net change in length of either muslce
countercurrent action
one muscle shortens at both joints as the antagonists lengthens correspondingly and thereby gains tension at both ends
ballistic movement
movements that are initiated by vigorous contraction and completed by momentum
example of ballistic movement
throwing, striking, kicking
what should you do in the early stages of learning ballistic movement
concentrate on form rather than accuracy
3ways termination of ballistic action occurs
by contracting antagonist muscle
by passive resistance of ligaments or other tissues at limits of motion
by the interference of an obstacle
example of contracting antagonist muscles
forehand drive in tennis
example of passive resistance of ligaments or other tissues at limits of motion
throwing motion
example of interference of an obstacle
chopping wood
methods of studying actions of muscle
conjecture & reasoning dissection inspection & palpation models & gadgets muscle stimulation electromyography (EMG)
conjecture & reasoning
using an educated guess
dissection
meaningful basis for visualization of muscle’s potential movement
inspection & palpation
valuable method for superficial muscles
models
used for demonstration
muscle stimulation
contraction of individual muscles
uses outside source of electrical stimulation
electromyography
based on the fact that contracting muscles generate electrical impules
reveals both intensity and duration of muscle activity
cannot indicate nature of contraction or muscle action
if angle of attachment is very shallow,
most of the tendon will produce a force alone the bone
if angle of attachment is fairly large
will have a much larger rotary component of force
what happens if angle of attachment has many muscles
in many muscles
the angle changes throughout ROM
what muscle generates tension at 90 degree angle to the bone, it i the most efficient at producing joint motion
