MUSCLES
1
FUNCTIONS OF MUSCULAR
SYSTEM
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Body movement
Maintain posture
Respiration
Produce body heat
Communication
Constriction of organs and blood vessels
Heartbeat
2
Muscle Types

Skeletal: elongated
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Smooth: spindle shaped
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Moves the skeleton
Voluntary
striated
Found in organs and lining of blood vessels
Involuntary
no striations
Cardiac: cylindrical shaped
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
involuntary (only responds to direct electrical stimulation)
3
striated
Connective Tissue Sheaths in
Skeletal Muscle
4
Figure 10.1a
Connective Tissue Sheaths

The MUSCLE FASCIA is loose connective tissue on the
outside of the muscle. It creates a slippery surface for
muscles to rub against each other. Superficial to the fascia is
the fat of the hypodermis layer. Deep to the fascia is the
EPIMYSIUM, (dense irregular fibrous connective tissue),
and which eventually becomes the tendon (which is
connected to bone). The epimycium extends into the muscle
belly to form compartments called FASICLES. This tissue
surrounding the fascicles is now called the PERIMYCIUM.
Each fascicle contains MUSCLE FIBERS, which are
individual muscle cells, each one surrounded by
ENDOMYCIUM. When you eat steak and find it’s stringy,
each string is a fascicle.
5
TYPES OF MUSCLE PATTERNS
The fascicles are aligned in certain directions,
and we use the patterns to classify muscle types:
 PARALLEL
 PENNATE
 CONVERGENT
 CIRCULAR
6
PARALLEL MUSCLE
The fascicles are parallel.
They are long fibers, which
can contract to 75% of their
length. They contract a long
way, but they are relatively
weak, because this muscles
are usually skinny, so there
are relatively few fascicles.
E.g. Sternocleidomastoid.
7
Arrangement
of Fascicles in
Muscles
8
Figure 11.3
PENNATE
PENNATE (means “feather shape”) MUSCLES: three types:



UNIPENNATE; looks like half a feather. The fascicles are
short, but there are more of them. They are stronger, but do
not have the same length contraction ability of the parallel
muscles.
BIPENNATE are fascicles that insert into the tendon from
both sides; they are stronger than unipennate (quadriceps).
MULTIPENNATE are the strongest (deltoid). The fascicles
are in multiple bundles inserting on one tendon
9
PENNATE
10
11
CONVERGENT
CONVERGENT MUSCLE has more fibers
than parallel, but contracts a greater distance
than pinnate. E.g. Pectoralis major.
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13
CIRCULAR MUSCLE
CIRCULAR MUSCLE (Sphincter) is arranged
in a circle, with a small area of tendon on the
sides. It allows closure of the eyes, mouth,
etc. They are not very strong, but they don’t
need to be.
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15
TERMS:
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ORIGIN = The region which usually doesn’t move when the
muscle contracts. Look at the biceps brachii; does the
shoulder move when I bend my arm? No; the shoulder =
origin.
INSERTION= The point of attachment that moves; bend
arm, radial tuberosity = attachment.
AGONIST = The main muscle for a particular action; bend
arm, biceps = agonist.
ANTAGONIST = Does the opposite action; bend elbow,
antagonist extends. Every muscle in the body has to have an
antagonist.
SYNERGIST = The muscle that helps the agonist. There are
several muscles that assist when the arm is bent.
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Muscle Attachments
17
Skeletal Muscle Characteristics
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
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Contractility

The ability to shorten with force

However, they lengthen passively, by gravity or by the contraction of an
opposing muscle.
Excitability

Capacity to respond to a stimulus (nerves)
Extensibility

Can be stretched

After a contraction, they can be stretched to their normal resting length
and beyond to a limited degree.
Elasticity
Can recoil to their original resting length after they have been stretched
Has thousands of nuclei per cell, unlike smooth and cardiac muscle
18
SKELETAL MUSCLE

They have thousands of nuclei because they
start from many stem cells that fuse together
into one skeletal muscle fiber.

Theses are very long fibers (biceps muscle
can be 8-10 cm).
19
Skeletal Muscle

Myoblasts exist in adults, so muscle heals well.
They act like a patch every time the muscle tears.
We don’t actually grow new muscle cells; we just
patch up the old ones when they are damaged.
A muscle cell torn in half can regenerate.
There are almost no muscle diseases for this
reason (muscular dystrophy is the main muscle
disease).
Muscles Overview Video
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http://www.youtube.com/watch?v=ren_IQPOhJc
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20
Skeletal Muscle: Longitudinal section
In skeletal
muscle
fibers, there
are light and
dark stripes
called
striations,
which can be
seen under a
microscope.
21
Skeletal Muscle ON CROSS
SECTION
22
A cross section of skeletal muscle
looks like bundles of circles
because you are looking at cut
fascicles.
23
Skeletal Muscle

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The plasma membrane of muscles is called a
SARCOLEMMA.
The cytoplasm of muscle cells is called
SARCOPLASM.
Muscle cells contain many mitochondria and
other organelles.
One type of unusual organelle found only in
muscle cells is called a myofibril. They are
packed in bundles and fill up most of the cell.
24
•
MUSCLE MYOFIBRILS
• Cylindrical organelles found within muscle cells
• Extend from one end of the muscle fiber (muscle cell) to the other
• Contain sarcomeres joined end to end.
• The sarcomeres are made of actin and myosin myofilaments
25
Skeletal Muscle: Longitudinal
section
These striations
(stripes) are caused
by dark and light
bands.
The dark band is
called an A band.
(There is an “A” in
dark)
The light band is
called an I band.
There is an “I” in
light)
26
This is all part of one muscle cell that has many nuclei.
27
Every
dark band + light
band is one
sarcomere
In the center of each light I band is a Z disc
One sarcomere is the area from one Z disc to the next Z disc.
So, each sarcomere extends from the middle of one light band to the
middle of the next light band. In the center of the dark band is a lighter 28
colored area called the H zone. It is the area of the myosin without heads.
SARCOMERES
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The striations result from the internal structure of SARCOMERES
within the sarcoplasm.
The sarcomere is the basic structural and functional unit of
skeletal muscle. The sarcomere is what contracts.
Each sarcomere

Extends from one Z disc to the next Z disc

Has a light colored H zone in the center (found in the middle of
the dark band, which is in the center of the sarcomere. It is the
area of myosin in the center that does not have myosin heads).

Contains parts of two I (light) bands and all of one A (dark) band

Contains overlapping actin and myosin myofilaments.
29
Note: the I band consists only of actin myofilaments.
The A band consists of both actin and myosin.
30
31
Actin and Myosin

Sarcomeres consist of two types of myofilaments
made out of protein:

thin (ACTIN) myofilaments



Look like two strands of beads twisted together.
Actin myofilaments are attached to the Z disc at one end.
thick (MYOSIN) myofilaments.

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Both ends of a thick filament are studded with knobs
called myosin heads (look like little golf clubs).
Myosin is NOT attached to the Z disc.
32
33
Actin
Myosin
Actin
Myosin
Sarcomere model video 1
Sarcomere model video 2
34
Don’t confuse these terms!
MUSCLE FASCICLE: a group of muscle fibers,
surrounded by perimysium.
MUSCLE FIBER: a single muscle cell
MYOFIBRIL: a long organelle inside a muscle fiber,
contains actin and myosin myofilaments.
MYOFILAMENTS: these are proteins, and there are two
types: actin (with troponin and tropomyosin) and myosin.
The myofilament is the lowest level of organization that is
composed of actin, myosin, troponin, and tropomyosin
proteins.
Therefore, a myofilament is part of a myofibril, which is
inside a muscle fiber, which is inside a muscle fascicle.
35
MECHANISM OF CONTRACTION
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The Sliding Filament Theory
Contraction results as the myosin heads of the thick filaments
attach like hooks to the thin actin filaments at both ends of the
sarcomere and pull the thin filaments toward the center of the
sarcomere.
The myosin head is like a hook with a hinge. After a myosin
head pivots at its hinge, it draws the actin closer, then lets go,
springs up again to grab the actin filament again, pulls it closer,
and it keeps repeating this until the entire actin filament has
been drawn in as far as it can go.
The sites where the myosin heads hook onto the actin are called
cross-bridges.
36
37
Sarcomere Contraction
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The complete process of contraction of the sarcomere takes
only a fraction of a second.
The actin and myosin filaments do not shorten; they
merely slide past each other.
The energy required is ATP.
The A band (dark stripe) in a sarcomere does not
change length in a contraction.
This sliding filament mechanism begins whenever calcium
ions bind to the thin filament.
Where does the calcium come from?
38
SARCOPLASMIC RETICULUM AND
T TUBULES
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Within the cytoplasm of all body cells is an
endoplasmic reticulum.
The endoplasmic reticulum in muscle cells is
called the SACROPLASMIC RETICULUM.
It surrounds each sarcomere like the sleeve of a
loosely crocheted sweater.
39
Sarcoplasmic
reticulum is in
blue
T tubules are in
yellow
40
Calcium is needed
for muscle contraction

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The sarcoplasmic reticulum stores a lot of calcium
ions, which are released when the muscle is stimulated
to contract.
The calcium diffuses out of the sarcoplasmic
reticulum and lands on the actin filaments, where they
trigger the sliding filament mechanism of contraction.
After the contraction, the calcium ions are pumped
back into the sarcoplasmic reticulum for storage, and
they don’t want to go (against their concentration
gradient), so it will cost some ATP.
41
Calcium is needed for muscle
contraction


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ACTIVE TRANSPORT is required to return the
calcium ions to the sarcoplasmic reticulum.
It also requires energy to break the cross-bridge so the
myosin head can cock back again, ready to spring onto
the next binding site.
Therefore, ATP is used twice.
 ATP is used to return calcium to the sarcoplasmic
reticulum
 ATP is used to cock back the myosin heads
42
ATP is required for contraction

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ATP attaches to the myosin myofilaments
 Provides energy for the movement of the cross
bridges
ATP is required for muscle relaxation
ATP releases part of its energy as heat.
 That is why we get hot when we exercise
 When we are cold, we shiver (muscle contraction)
to warm up.
In order for the mitochondria to produce enough ATP,
it needs oxygen and the sugars that are in storage.
43
For contraction to take place, you need a
nerve signal and calcium

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For skeletal muscle to contract, the synaptic knob of
a neuron must first release a chemical called
ACETYLCHOLINE onto the region where it sits
on the muscle cell, known as the ENDPLATE.
The nerve signal is called an ACTION
POTENTIAL.
It causes a release of calcium from the sarcoplasmic
reticulum, which causes contraction. So, Calcium is
also needed for muscle contraction.
44
Muscle Contraction
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In a muscle fiber, an action potential results in
muscle contraction. How does this happen?
The action potential continues to travel along the
sarcolemma (cell membrane of the muscle).
Part of this electrical impulse breaks away from
the sarcolemma and travels down the T-tubules,
while the rest of the electrical impulse continues
longitudinally down the muscle cell to the next
sarcomere and T-tubule.
45
T tubules are in
yellow
46
T TUBULES

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T TUBULES (“T” stands for “transverse”)
are continuations of the sarcolemma (cell
membrane) which invaginate to the deepest
regions of the muscle cell.
Since the T tubules conduct the nerve impulse
throughout the muscle cell, all the sarcomeres
of that cell contract at the same time.
47
Muscle Contraction

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The action potential of the nerve goes down the Ttubules and causes calcium to leak out of the
sarcoplasmic reticulum.
The calcium causes the muscle fibers to contract.
After a while, the calcium gets pumped back
where it came from, the muscle fibers relax,
although it requires gravity or another muscle to
pull the sarcomere back to its original length.
How does the calcium cause the muscle fibers to
contract?
48
TROPOMYOSIN is a single long protein strand like a
piece of yarn that winds around the actin filament.
 Tropomyosin blocks actin’s attachment site for the
myosin head, so the myosin “hook” has nothing to grab
onto, thus preventing contraction.
TROPONIN is a globular complex of three proteins, and
is found in clumps around the tropomyosin protein.
 Troponin is the specific molecule that provides the
calcium binding site on actin.
 Calcium binds to troponin and causes troponin to move
a little, taking the tropomyosin thread with it, so the
attachment sites on the actin molecule are now
exposed. The myosin heads can now hook into the
exposed sites on the actin myofilament.
Both troponin and tropomyosin cover the actin filament
when the muscle is relaxed.
49
This is an
illustration of
an actin
molecule.
You can see
the thready
tropomyosin
and the
globular
troponin
proteins
wrapping
around the
doublestranded
actin.
50
When
calcium binds
to the
globular
troponin, it
moves,
taking the
tropomyosin
thread with it.
This exposes
the myosin
binding site
on the actin.
51
Calcium in muscle contraction
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When the muscle cell is stimulated to contract by an
action potential, calcium channels open in the
sarcoplasmic reticulum and release calcium into the
sarcoplasm.
Some of this calcium attaches to troponin, causing a
conformational change that moves tropomyosin out of the
way so that the myosin heads can attach to actin and
produce muscle contraction.
When the calcium gets pumped back where it came from,
the tropomyosin protein blocks the myosin head again so
it can no longer get its hook into the actin filament, and
the muscle will relax.
52
Rigor Mortis


A new ATP molecule must bind to the myosin
before the cross-bridge can be released. When
ATP is not available after a person dies, the
cross-bridges that have formed are not released,
causing muscle to become rigid (rigor mortis)
NOTE: Sarcomeres lengthen during muscle
relaxation only if gravity or an opposing muscle
pulls the sarcomere back to its original length.
53
Muscle Contraction

Muscle Contraction

http://www.youtube.com/watch?v=CepeYFvqmk4

Sarcoplasmic Reticulum

http://www.youtube.com/watch?v=InIha7bCTjM&NR=1
54
Sequence of events
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The action potential reaches the cell membrane
The action potential reaches the T-tubules
The ion channels in the sarcoplasmic reticulum open
Calcium ions move along their concentration gradient
Actin forms cross-bridges to myosin
The actin myofilaments move closer to each other,
causing contraction of the sarcomere.
NOTE: A muscle fiber will not respond to a stimulus
until that stimulus reaches the threshold level.
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NOTES



Troponin is found in both skeletal muscle and cardiac
muscle, but not in smooth muscle.
Both cardiac and skeletal muscles are controlled by
changes in the intracellular (“inside the cell”) calcium
concentration (not blood calcium concentration).
When muscle calcium levels are normal, the muscles
contract normally, and when muscle calcium levels fall,
the muscles might not be able to contract. So the
osteoclasts will take calcium out of the bone and put it
into the blood where it can go replenish the ER.
56
Muscle Contraction
A muscle TWITCH is one single muscle fiber
contraction.
 It takes 1/20th of a second.
 How is it that I can pick up and hold a chair if the
fiber only contracts for 1/20th second?
 There are ten thousand fibers per muscle; each
one contracts at different intervals, so contraction
is maintained, just like tug-of-war. One person in
ten can drop the rope and get a better grip
because the others are maintaining the tension.
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Motor Units
A MOTOR UNIT is a single neuron and all of
the muscle fibers on which it synapses. The
neuron is like a mother, and the muscle cells it
attaches to are her children.
If one neuron sends a signal, only its muscle
fibers contract (the motor unit). This allows
for strength variations in lifting a chair vs. an
eraser. For full strength, all the motor units
contract. For half strength, half of the motor
units contract.
58
Motor Units
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A neuron that lands on skeletal muscle is called a motor neuron,
because it moves the body.
The action potential continues from one motor neuron in the
brain to the next motor neuron in the spinal cord, which is the
one that goes out and lands on the skeletal muscle fibers.
A single motor neuron and all the skeletal muscle fibers it
innervates constitute a motor unit.
Your tongue is made of muscle. Every 10 muscle fibers has one
motor neuron assigned to it. So, there are many motor units
there. This allows for precise movement. However, large thigh
muscles may have as many as 1000 muscle fibers per neuron,
59
which gives more strength, but not precision.
Motor Units


The muscles of the back are larger motor
units (a larger household….one neuron for
1000 muscle fibers). Since there are fewer
motor units present, we get strength, but less
precision.
The muscles that move the tongue have
smaller motor units (one neuron for 10
muscle cells). Since there are many motor
units present = less strength, more precision.
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Physiology of the Neuromuscular
Junction

VIDEO

https://www.youtube.com/watch?v=hzXVe4R
S8-A
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63
Physio
Fast and Slow Twitch


Muscle fibers exist in two basic forms: slow
and fast twitch. They're also known as red and
white, or type 1 and type 2.
Fast twitch (white or type 2) fibers are
dominant in sprinters and power athletes, and
slow twitch (red or type 1) fibers dominate in
endurance athletes.
64
Physio
Fast and Slow Twitch


Slow skeletal muscle fibers have a better
ability to endure because they are resistant to
fatigue and contract slowly.
Fast skeletal muscle fibers have relatively few
mitochondria that generate most of their ATP
via glycolysis, so they have low resistance to
fatigue, and they wear out quickly.
65
Physio
Muscle Twitch Phases
A muscle twitch has three phases
 The lag phase is the time between the application of a
stimulus and the beginning of contraction.
 The contraction phase is the time of contraction.
 The relaxation phase is the time during which the
muscle relaxes.

The refractory period is the time between muscle
twitches.
66
Physio
Refractory
period
67
Physio
Force of Contraction




The strength of muscle contraction can vary from weak to
strong. For example, the force generated by muscles to lift a
feather is much less than the force required to lift a 25 pound
weight.
The force of contraction produced by a muscle is increased in
two ways:
Summation, which involves increasing the force of contraction
of the muscle fibers within the muscle
Recruitment, which involves increasing the number of muscle
fibers contracting
68
Physio
Summation






The force of contraction of individual muscle fibers is increased by rapidly
stimulating them.
Stimulus frequency is the number of times a motor neuron is stimulated per
second.
When the stimulus frequency is low, there is time for complete relaxation of
muscle fibers between twitches.
As stimulation frequency increases, there is not enough time between
contractions for muscles to completely relax.
Thus, one contraction summates, or is added onto, a previous contraction. As
a result, the overall force of contraction increases.
Tetanus is the condition in which a muscle remains contracted between
stimuli without relaxing.
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TETANUS TOXIN


A toxin caused by a certain bacteria can cause muscle to remain
contracted (in tetanus).
It quickly results in death because the diaphragm and other
respiratory muscles cannot function properly, and the person
suffocates.
The bacteria that make this toxin
live deep in the soil and cannot
survive in air.
If you step on something that
imbeds soil deeply into your
tissues (like a rusty nail), you
might contract the bacteria.
You will need a tetanus shot
before the toxins accumulate.
70
Physio
Recruitment




In recruitment, the strength of contraction of the muscle is
increased by increasing the number of motor units
stimulated.
When only a few motor units are stimulated, a small force of
contraction is produced, because only a small number of muscle
fibers are contracting.
As the number of motor units stimulated increases, more muscle
fibers are stimulated to contract, and the force of contraction
increases.
Maximum force of contraction is produced in a given muscle
when all the motor units of that muscle are stimulated, or
recruited.
71
Physio
Recruitment



Motor unit recruitment allows muscles to have slow,
smooth sustained contractions so our movements are
not jerky.
If all the motor units in a muscle could be stimulated
simultaneously, a quick, jerky motion would occur.
Because the motor units are recruited gradually so that
some are stimulated and held in tetanus while
additional motor units are recruited, slow, smooth,
sustained contractions occur.
72
Physio
Types of Muscle Contractions
Muscle contractions are classified as either isometric or isotonic. Most muscle
contractions are a combination.








Isometric (equal distance)
tension increases during contraction
length of the muscle does not change
Example is when you push against a wall or try to pick up an object
that is too heavy to lift
Isotonic (equal tension)
tension is generally constant during contraction

Although in one type of isotonic contraction, the tension increases
Length of the muscle changes (either increases or decreases).
Example is when you lift a weight.
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Concentric and Eccentric
Contractions



Physio
Two types of isotonic contractions:
CONCENTRIC CONTRACTIONS are isotonic contractions
in which the muscle tension increases as the muscle shortens.
Most movements performed by muscle contractions are of this
type.
ECCENTRIC CONTRACTIONS are isotonic contractions in
which tension is maintained as the muscle lengthens. An
example is when a person lets down a heavy weight slowly.
Substantial force is produced in the muscles and injuries can
occur from repetitive eccentric contractions, such as in the
hamstring muscles when a person runs downhill.
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Muscle Tone



Even when muscles are relaxed, some of their fibers
are still contracting, giving the muscle some tone.
Therefore, the normal state of a muscle, with some
contraction, is called muscle tone. This is important
in posture so you can stand upright but mostly relaxed.
Muscle tone refers to the constant tension produced by
muscles of the body over long periods of time. It is
responsible for keeping the back and legs straight, the
head held in an upright position, and the abdomen
from bulging. it declines during REM sleep.
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Motor Neurons



A neuron (nerve cell) that innervates (supplies)
skeletal muscle is called a motor neuron (causes the
body to move). There are 2 motor neurons involved
in this task.
The Upper Motor Neuron has its cell body in the
brain, and its axon (like a stem) lands on the cell
body of the Lower Motor Neuron, which is in the
spinal cord.
The axon of the Lower Motor Neuron leaves the
spinal cord and innervates the muscle.
76
77
Upper and Lower Motor Neurons
(in red)
Upper
motor
neuron
Lower motor
neuron
78
Muscle Tone


Hypertonia
 Can present clinically as either spasticity (jerking) or
rigidity (constantly tense). Seen in upper motor neuron
diseases, such as multiple sclerosis or cerebral palsy.
 “Hyper = upper”(hypertonia = UMN disease)
Hypotonia
 Seen in lower motor neuron diseases (spinal cord
damage and ALS/Lou Gehrig Disease)
 Presents clinically as muscle flaccidity, where the limbs
appear floppy, stretch reflex responses are decreased, and
the limb’s resistance to passive movement is also
decreased. “Hypo = lower” (hypotonia = LMN disease) 79
Muscle Tone




Upper Extremity Tone, normal VIDEO
Upper Extremity Tone, abnormal VIDEO
Lower Extremity Tone, normal VIDEO
Lower Extremity Tone, abnormal VIDEO
80
Muscle Hypertonia: Spasticity



Clinically spasticity is defined as velocity dependent
resistance to stretch.
Passively moving (the doctor does the movement) the
patient’s elbow or foot quickly will elicit spastic twitches, but
passively moving elbow or foot slowly is normal.
It occurs from upper motor neuron lesions (scar, tumor) or
other damage, such as multiple sclerosis, which is an
autoimmune condition, or cerebral palsy (lack of oxygen at
birth).
81
Muscle Spasticity


There is a difference in cause of two of the most
common spasticity conditions, spastic diplegia
(cerebral palsy) and multiple sclerosis.
In spastic diplegia, the upper motor neuron lesion
arises often as a result of neonatal asphyxia (lack of
oxygen in a newborn), while in conditions like
multiple sclerosis, spasticity is from multiple
sclerosis, which is an autoimmune destruction of
the myelin sheaths around nerve endings.
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Muscle Spasticity

Causes include





Spastic diplegia (Cerebral palsy)
Multiple sclerosis
Spinal cord injury
Stroke
Test for clonus to see if spasticity is present.
83
Muscle Clonus

Clonus (from the Greek for "violent, confused motion") is a series
of involuntary muscular contractions initiated by a reflex.
Clonus is a sign of certain neurological conditions, and is
particularly associated with upper motor neuron lesions such as
in spastic diplegia, multiple sclerosis, stroke, spinal cord damage.
Be able to describe how to perform a clonus test, and what a
positive test looks like: Clonus is most commonly tested for in
the ankles, where it is tested by rapidly dorsiflexing the foot.
If the foot then jerks 5 times or more, clonus is present. A
positive clonus test means the patient has spasticity, usually
due to an UMN disorder.
84
VIDEO: Ankle clonus

http://www.youtube.com/watch?v=iWEJIVO85TI



Muscle Rigidity


Unlike spasticity, rigidity is velocityindependent resistance to passive stretch.
There is uniform increased tone whether the
elbow is passively moved quickly or slowly.
85
Muscle Fasciculations




These are small, local, involuntary muscle
contractions, usually in the face, lips, eyes.
Fasciculations have a variety of causes, the
majority of which are benign, but can also be
due to disease of the lower motor neurons.
Fasciculations VIDEO
Tremor VIDEO
86
Muscle Fasciculations

Benign causes of fasciculations include:

Magnesium deficiency






Diarrhea
Overexertion
Inadequate intake from diet (almonds are a good
source of magnesium)
Dehydration
Fatigue
A small neuron dying can also cause
fasciculations.
87
Muscle Fasciculations

They can also be caused by long-term use of:






Benadryl (antihistamine)
Dramamine (for nausea and motion sickness).
Caffeine
Sudafed (for allergies)
Asthma medicines
ADD medicines
88
Muscle Fasciculations

More serious conditions causing
fasciculations include




Fibromyalgia
Myasthenia Gravis
Lyme Disease
Rabies
89
Hyperreflexia



We talked about hypertonia; some people have
hyperreflexia.
The most common cause of exaggerated reflexes is
spinal cord injuries (upper motor neuron diseases).
Other causes include
 Medication
 Stimulants
 Hyperthyroidism
 Electrolyte imbalance
 Severe brain trauma.
90
Hyporeflexia


This means diminished or absent reflexes.
The most common cause is lower motor
neuron diseases.
91
Muscle Strength and Coordination






Upper Extremity Strength, normal VIDEO
Upper Extremity Strength, abnormal VIDEO
Lower Extremity Strength, normal VIDEO
Lower Extremity Strength, abnormal VIDEO
Strength Evaluation using squats VIDEO
Hand coordination using Rapid Alternating
Movements (RAM) VIDEO
92
Muscle Contractures




Muscle contractures can occur from paralysis,
muscular atrophy (immobilization from a cast),
muscular dystrophy, and chronic spastic conditions
like cerebral palsy.
Fundamentally, the muscle and its tendons shorten,
resulting in reduced flexibility.
Muscle contractures in tendons are caused from the
fibrinogen leaking out of the fibroblasts, which turn
the elastic fibers into inelastic fibers.
Most treatments involve surgery, so physical therapy
efforts focus on prevention of contractures.
93
Energy Requirements of Muscle



What fuel does a car use?
 Gasoline
What fuel does a candle use?
 Wax
What fuel do humans use?
 Oxygen?
 NO
 Sugars?
 NO
 ATP
 YES
94
ATP





Where do we get ATP?
We can make a little ATP in the cytoplasm of our cells, but not
enough to live on.
Most of our ATP is made by the mitochondria inside our cells.
Mitochondria are like little protozoa (animals) that live in our
cells. Each cell has hundreds of them. Muscle cells have
thousands of them.
What is their fuel?
 Oxygen and glucose
 THAT is why we need to inhale oxygen and consume
sugars….to feed our mitochondria so they can make ATP for
95
us!
Energy Requirements
For Muscle Contraction





In order for the muscle mitochondria to produce
enough ATP, they need oxygen (for their own aerobic
respiration) and sugars that are in storage.
Mitochondria can only perform aerobic respiration.
What can we do to make ATP if our muscle cells run
out of oxygen?
Start performing anaerobic respiration.
We can do this ourselves in the cytoplasm of our cells.
96
Making ATP by Aerobic
Respiration
Aerobic cellular respiration
 Breaks down glucose to produce ATP
 Takes place in the mitochondria
 Requires oxygen
 Waste products are CO2 and H2O (we exhale them)
 The good thing about making ATP from our
mitochondria is that we can make a LOT of it.
 The bad things are that it takes longer to make it,
and it requires oxygen, and a muscle cell may have
used up all the oxygen during a sprinting run.
97
Making ATP by Anaerobic
Respiration
Anaerobic cellular respiration
 Breaks down glucose to produce ATP
 Takes place in the cytoplasm
 Does not require oxygen
 Waste product is lactic acid
 The good thing about making ATP this way is
that we can make it FAST.
 The bad thing is that it does not make much
ATP, and we deplete the reserves quickly.
98
Lactic Acid



The waste product of aerobic respiration is carbon
dioxide and water. These are not a problem…we
eliminate them by exhaling.
The waste product of anaerobic respiration is lactic
acid, which can irritate muscle fibers, causing muscle
pain (stitch in your side) and muscle cramps.
We deactivate lactic acid by adding oxygen to it.
Therefore, breathing heavily adds the oxygen to our
system to deactivate lactic acid, and the muscle pains
go away. That’s also why we use ultrasound machines
for therapy on sore muscles. It increases circulation.
99
ATP and Creatine Phosphate






What do we do when we run out of ATP?
Muscle fibers cannot stockpile ATP in preparation for future
periods of activity.
However, they can store another high energy molecule called
creatine phosphate, which is the storage form of ATP.
Creatine phosphate is made from the excess ATP that we
accumulate when we are resting.
During short periods of intense exercise, the small reserves
of ATP existing in a cell are used first.
Then creatine phosphate is broken down to produce ATP.
100
Aerobic vs. Anaerobic
Respiration





Why does sprinting require anaerobic respiration?
 We use up all of the ATP faster than we can make it.
When we run out of ATP, we break down creatine phosphate to
make more ATP.
When we run out of ATP and creatine phosphate, we start using
anaerobic respiration to make more ATP.
When we run out of glucose, or too much lactic acid is built up,
we have to stop and rest.
Anaerobic metabolism is ultimately limited by depletion of
glucose and buildup of lactic acid within the muscle fiber.
101
Sprint Runners



Why do sprint runners tire out during the last part of a
fast run?
Sprinting is an anaerobic activity…the oxygen
requirement is quickly exceeded, so the muscle has to
use anaerobic respiration to continue to contract. This
requires a lot of glucose and also results in a buildup
of lactic acid.
Once the sprint-runner has used up the available
glucose, or has produced too much lactic acid, the
muscles fatigue.
102

Sprint Runners http://www.youtube.com/watch?v=MTn1v5TGK_w
Oxygen Debt





Anaerobic respiration produces lactic acid, which
causes the painful cramps because it creates an oxygen
debt.
The amount of oxygen needed to replenish the
supply following aerobic demand is called the
oxygen debt.
When you continue to breathe heavily after exercising,
it means you have an oxygen debt.
Muscles can do without oxygen for a while pretty well,
unlike the brain.
To pay back a minor oxygen debt, you just have to
breathe heavily for a while.
103
Oxygen Debt



This heavy breathing brings in oxygen, which is used
to convert lactic acid to glucose, replenish the depleted
ATP and creatine phosphate stores in the muscle
fibers, and to replenish oxygen stores in the lung,
blood, and muscles.
After the oxygen debt has been paid back, breathing
returns to normal.
People who are in good physical condition can carry
out both aerobic and anaerobic activities efficiently,
and do not suffer from an oxygen debt for very long.
104
Myoglobin



The reason why muscles can do without oxygen for a while is
because they have myoglobin. Myoglobin is an iron- and
oxygen-binding protein found in the muscle tissue of
mammals.
It is related to hemoglobin, which is the iron- and oxygenbinding protein in blood, specifically in the red blood cells.
The only time myoglobin is found in the bloodstream is when
it is released following muscle injury. It is an abnormal
finding, and can be diagnostically relevant when found in
blood.
105
Myoglobin




Myoglobin binds to oxygen more strongly than
hemoglobin.
It acts as an oxygen-storage molecule and delivers
the oxygen to cells when needed.
High concentrations of myoglobin in muscle cells
allow organisms to hold their breaths longer.
Diving mammals such as whales and seals have
muscles with particularly high myoglobin levels.
106
Myoglobin




Myoglobin forms pigments responsible for making meat red. The color
that meat takes is partly determined by the oxidation states of the iron
atom in myoglobin.
When meat is raw, the iron atom is in the +2 oxidation state (Fe+2).
Meat cooked well done is brown because the iron atom is now in the +3
oxidation state (Fe+3), having lost an electron.
Under some conditions, meat can also remain pink all through cooking,
despite being heated to high temperatures. If meat has been exposed to
nitrites, it will remain pink because the iron atom is bound to NO, nitric
oxide (e.g., corned beef or cured hams). Grilled meats can also take on a
pink "smoke ring" that comes from the iron binding to a molecule of
carbon monoxide.
107
Myoglobin




Rhabdomyolysis is the condition when myoglobin is
released from damaged muscle tissue.
Released myoglobin is filtered by the kidneys, but it
damages them, so it can lead to renal failure.
High blood levels may indicate the person is having
a heart attack, or it could just be a muscle injury.
Therefore, CK, cTnT, ECG, and clinical signs
should be taken into account to make the diagnosis
of a heart attack.
108
Creatine kinase (CK)


CK is the enzyme used to get ATP out of
storage (ATP is stored as creatine).
High blood levels of CK may indicate
myocardial infarction (heart attack),
rhabdomyolysis (severe muscle breakdown),
muscular dystrophy, the autoimmune
myositides, or acute renal failure.
109
Troponin (cTnT)


Troponin levels in the blood can be used as a
test of several different heart disorders,
including myocardial infarction.
Troponin-I is highly specific for cardiac
muscle necrosis. Serum levels rise 4-8 hrs
after onset of chest pains, peak at 12-16 hrs
and return to baseline within 5-9 days.
110
EXERCISE

1.
2.
3.
4.
5.
There are many physiological benefits of
exercise:
Improved muscular strength, endurance,
flexibility
Improved cardio-respiratory endurance
Increased bone density and strength
Relief from depression
Increased HDLs (good cholesterol)
111
Hypertrophy




Weight training and other exercises can cause muscles to hypertrophy
(enlarge). This occurs as more myofilaments and myofibrils are produced
inside a myofiber (muscle cell), causing the muscle cell to enlarge. The
number of mitochondria also increases, causing additional enlargement.
However, you don’t grow new muscle cells. The number of cells in a
skeletal muscle remains relatively constant following birth. Myoblast stem
cells don’t grow into new muscle cells; they just patch up damaged cells.
Hypertrophy because:

Increase in number of myofibrils inside a muscle cell

Which causes the increase in size of individual muscle cells (myofibers)
Muscle hypertrophy is greater in males due to the hormone testosterone.
112
113
Hypertrophy





Eating protein does not automatically increase muscle. The
average person only needs 2 three ounce servings of protein per
day, six ounces if you work out.
Two ounces is the size of a deck of playing cards.
Three ounces is like one mini hamburger.
Most people eat too much meat.
Excess meat causes kidney damage (from the amino ACIDS)
Fun Fact: -You use 200 muscles to take one step.
114
How much meat per day?




Most people need around 0.8 grams of protein per day per 2.2
pounds of body weight, according to registered dietitian Reed
Mangels.
Consuming around 46 grams of protein per day if you're
female and 56 grams per day if you're male will meet your
protein needs, whether you get your protein from meat or
from plant sources.
A 3-ounce portion of meat contains 21 to 24 grams of protein.
Two 3-ounce meat servings per day would supply all your
protein needs, but this much meat could include a large
amount of saturated fat, which could increase your risk of
heart disease.
115
Fun Facts






A muscle cell is about as thin as a hair.
Muscles make up 1/3 of your body weight.
There are 655 muscles in the body…that is
three muscles per bone!
We all have the same number of muscle cells.
Muscles can generate 40 pounds per square
inch.
If all the muscles in the body were able to
contract at once, they could pull 25 tons!
116
Fun Facts

Myths About Women’s Body Building

http://bodybuilding.about.com/od/womensfitnesstopics/a/womenmyths.htm
117
Atrophy






Lack of use causes muscle ATROPHY. This happens quickly.
Astronauts can lose 40% of their muscle in two weeks! It is
regained quickly, too.
Atrophy is a decrease in muscle size because of the decrease in
myofilaments within muscle fiber.
Casting a broken limb also leads to temporary atrophy. In 3
weeks, they need a fresh cast because it is too loose.
Severe atrophy involves the permanent loss of skeletal muscle
fiber and the replacement of those fibers by connective tissue.
Damage to the nervous system, or a severed motor nerve can
cause atrophy. The muscle becomes flaccid (having no tone) .
118
More info on Muscle Atrophy
Muscular Dystrophy


This refers to a group of inherited muscle
disorders in which skeletal, cardiac, and smooth
muscle tissue degenerates and the person
experiences progressive weakness and other
symptoms, including heart problems.
The muscle is replacement by fat and other
connective tissue.
119
Muscular Dystrophy


MUSCULAR
DYSTROPHY
This is a genetic lack of a
protein called
DISTROPHIN. It causes
the muscle tissue to harden,
inhibiting contraction,
causing progressive
paralysis.
 Duchenne muscular
dystrophy is more
common in males.
120
Research on Muscular Dystrophy



Two new types of stem cells have been found
that can seek out injured muscle tissue and
replace the damaged cells.
Researchers in Italy used stem cells from
blood vessels to repair muscle in mice with
muscular dystrophy.
Canadian scientists found that stem cells from
damaged muscle give rise to new muscle
fibers.
123
Muscle Problems



Tendonitis is an inflammation of the tendon or
its attachment point. It usually occurs from
overuse of the muscle to which the tendon is
attached.
A strain is a tear in a muscle. Remember, a
sprain is a tear in a ligament.
A muscle strain will heal faster than a torn
ligament because muscles have good blood
supply and ligaments do not.
124
Treatment for Injuries: RICE


Rest
Ice



Compression



20 minutes on, 20 minutes off for 3 days
Ice pack or frozen bag of peas!
Ace wrap from distal to proximal
Don’t leave any openings while wrapping
Elevation
125

Above the heart
Treatment for Injuries


Ice for the first 72 hours (NO heat!)
Anti-inflammatory medicines




Ibuprofin, 600 mg TID (3x a day)
Over the counter (OTC) pills are 200 mg
Heat and massage as needed after third day.
Can try a muscle stimulator too…works pretty
well!
126
Muscle Spasms



Muscle spasms/cramps are sudden and involuntary muscle
contractions. They are painful, spastic contractions that are
usually caused from overexertion. Lactic acid builds up and
irritates the overused muscles, causing inflammation. If the
muscle remains in spasm for longer than a few minutes, might
need heat and massage to increase circulation.
Avoid spasms by stretching before and after activities.
For people with frequent low back spasms throughout the day, a
portable muscle stimulator that clips to the belt will help a
great deal.
127
Muscle
stimulator to
relieve
muscle
spasms or to
prevent
muscle
atrophy in
casts
$59
http://www.m
edicalproduct
sonline.org/m
eprondi75mu.
html
128
129
$3.50
http://www.m
edicalproduc
tsonline.org/r
ecaclel10pa.
html
130
Fibromyalgia (muscle and tissue pain)





Common disorder in adults, especially women
Painful muscles, debilitating fatigue, sleep
disturbance, and joint stiffness
Many trigger points: painful lumps in muscles
Treatment includes anti-inflammatory
medicines, physical therapy, acupuncture, and
exercise.
Muscle stimulators help
131
Fibromyalgia


The American College of Rheumatology
guidelines that require a minimum of 11 out
of 18 specific tender points for a fibromyalgia
diagnosis.
Fewer than 11 tender points may also indicate
fibromyalgia, particularly if you also have
severe fatigue and widespread pain that has
lasted more than three months.
132

Fibromyalgia
points of
tenderness
133
Fibromyalgia


There is a blood test to help diagnose the
condition.
The FM/a test identifies markers produced by
immune system blood cells in people with
fibromyalgia.
134
Fibromyalgia Treatment



There is no cure for fibromyalgia, and people
with the condition usually have it for life.
However, it is not likely to get worse as you
age and it does not damage muscles, tendons,
or ligaments.
Many people are able to reduce their
symptoms with a combination of exercise,
medication, physical therapy, and relaxation.
135
Fibromyalgia Treatment




Exercise
 Daily walking, biking, water aerobics, or swimming for
20-30 minutes
Medication
 B12 to help repair nerves
 D5 Ribose to help you stay asleep better
 Magnesium supplements
Physical therapy
 Muscle stimulators
Relaxation
136
Ganglion Cysts





Ganglion cysts arise as outpouchings from fluid filled
areas such as the fluid around tendon sheaths.
When the fluid, called synovial fluid, leaks out from these
spaces, it can become a cystic structure.
Treatment is to drain the fluid with a needle, but the fluid
can be jelly-like and difficult to remove, and they
frequently grow back.
If conservative treatments fail to correct the cyst, an
operation can be done to excise the cyst.
Then you do a surgery to scoop out the whole cyst, find
the stalk and tie it off.
137
• Ganglion cyst
138
Baker’s Cyst




A Baker's Cyst, or popliteal cyst, is a collection of
fluid in the back of the knee joint.
A Baker's cyst is usually a symptom of another
problem, or it may be an incidental finding with no
significant meaning.
Most often in adults the Baker's cyst is found in
conditions where there is chronic swelling or fluid
accumulation in the knee joint.
These conditions include knee arthritis, meniscus
injuries, and ligamentous injuries.
139
Baker’s Cyst

Treatment of a Baker's cyst that is the result of a
problem within the knee consists of treating the
underlying problem. These treatments may include
anti-inflammatory medications and cortisone
injections.
140
• Baker’s Cyst
141

What is the Rotator Cuff?
Rotator Cuff Injury

http://www.youtube.com/watch?v=-tx2SqWz3BY

How do rotator cuff injuries occur?

http://www.youtube.com/watch?v=t6FCBBijROo

What is an MRI?

http://www.youtube.com/watch?v=H0adTNhzGxU

How does a CT scan work?

http://www.youtube.com/watch?v=81PeTqmtzjk

142
AGING


With aging, fibrous connective tissue
replaces some muscle fibers, causing
decreased strength.
As people age, the number of muscle
fibers decreases, and new ones cannot be
added.
143
FUN FACTS ABOUT STRENGTH

The strongest humans can lift about 3 times their own body weight, but the
average gorilla can lift 10 times its own body weight! Gorillas can lift 4,600
pounds. By the way, they don’t drink water. They get it by eating 50 pounds
of plants a day.

The rhino beetle can carry 800 times its own weight.

And, pound for pound, the African Crowned Eagle can carry more than a
cargo plane, because it can fly carrying up to 4 times it's own weight.
Something that would keep a cargo plane grounded.

But the strongest creature is the ant. If you had the strength of an ant, you
could lift over your head and carry 6,600 pounds.

VIDEO: Skeletal Muscles 3 mins
144
FUN FACTS







If we could jump like a locust, we could jump 300 feet. Locusts have massive muscles in their
thighs and it has elastic bands in its knees that are like stretchy springs that store energy. The
tendons in our fingers store enough energy for us to snap our fingers.
At 60 mph, the cheetah is fast, but the basilisk lizard runs so fast that it can walk on water and the
ostrich is just about the fastest animal on two legs.
What’s the fastest animal on Earth? The tiger beetle, which can run up to 171 times its size in one
second. Despite its famous reputation, the cheetah would have to run 770 kilometres per hour just
to catch up with it.
What’s the slowest animal in the world? The sloth. It is a species that moves just five times faster
than a snail!
The penguin burns twice as much energy as any other animal when walking. This is due to the fact
that its legs are very short, and so it must expend a lot of effort in order to get moving.
Elephants can't jump, not even with the help of hurricane-force winds. It is too heavy to lift all four
legs at the same time.
The flea, however, can jump up to 200 times its own height. This is equivalent to a man jumping
the Empire State Building in New York.
146
Smooth and Cardiac
muscle
147
SMOOTH MUSCLE CELLS



These are found around internal organs
(intestines, uterus, blood vessels).
They are involuntary and not striated.
When smooth muscle contracts around the
intestines, the movement is called
PERISTALSIS.
148
SMOOTH MUSCLE CELLS
•
•
•
•
•
Smooth muscle cells are small and spindle shaped,
usually with one nucleus per cell.
They contain less actin and myosin, and the
microfilaments are not organized into sarcomeres.
As a result, smooth muscle cells are not striated.
They contract more slowly and do not develop an
oxygen debt.
Smooth muscle cells can spontaneously generate
action potentials that cause the cell to contract.
149
SMOOTH MUSCLE CELLS
•
•
•
•
Smooth muscle is not under voluntary control,
whereas skeletal muscle is voluntary.
Some hormones in the digestive system can
stimulate smooth muscles to contract.
They have specialized cell to cell contacts that
allow the action potential to spread to all of the
smooth muscle cells in a given tissue.
This allows them to function as a unit and
contract at the same time.
150
Characteristics of smooth muscle






There are no distinct sarcomeres
They contract more slowly than skeletal muscle…their twitch
time is very long = several seconds
It doesn’t get tired (“I’m too tired to urinate!”)
They contract in response to neurons as well as hormones and
changes in local environment (amount of oxygen, lactic acid,
etc).
They may be autorhythmic (self-exciting); they can contract
spontaneously without being stimulated (like cardiac muscle).
They do not develop oxygen debt.
151
152
Smooth Muscle
153
CARDIAC MUSCLE CELLS



Only found in the
heart.
The cells are
involuntary (like
smooth muscle) and
striated (like skeletal
muscle).
They have
intercalated discs
which join each cell.
154
Cardiac Muscle
155
Cardiac Muscle




Cardiac cells are long, striated, and branching,
with one nucleus per cell.
The actin and myosin myofilaments are
organized into sarcomeres, but not as uniformly
as in skeletal muscle.
As a result, cardiac muscle cells are striated, but
not as distinctly as skeletal muscle.
Cardiac muscle is involuntary and does not
fatigue.
156
Cardiac Muscle



Cardiac muscle cells are connected to one
another by intercalated discs which facilitate
action potential conduction between
themselves.
This allows them to function as a unit and they
all contract together.
Contraction of cardiac cells is influenced by
hormones, such as epinephrine.
157
Cardiac Muscle



As one cell contracts, the action potential goes
through all the cells, and they all contract as a
unit. That’s why the heart contracts all at once.
It has an intrinsic beat. The cells contract on
their own, without a signal.
Even if you chop a heart up, each piece will
beat by itself!
158
Summary
Skeletal
muscle
Smooth
muscle
Cardiac
muscle
Many
One
One
Involuntary
or
voluntary?
Voluntary
Involuntary
Involuntary
Striated
or
non-striated
Striated
Non-striated
Striated
Number of
nuclei
per cell
Where
is it
found?
Inserts
onto bones
Intestines,
blood vessels,
other organs
Myocardium
of heart
MUSCLE
Adductors
Biceps femoris
Brachialis
Deltoid
Gastrocnemius
Gluteus medius
Gracili
Infraspinatus
Internal Oblique
Latissimus dorsi
Pectoralis major
Pectoralis minor
Psoas major
Quadriceps femoris
Rectus abdominis
Semimembranosus
Semitendinosus
Serratus anterior
Supraspinatus
Tensor fascia latae
Teres major
Trapezius
Triceps brachii
BEEF CUT
Top (inside) round
Bottom (outside) round
Shoulder rose
Outside chuck (chuck)
Round heel
Top sirloin
Inside round cap
Top blade
Sirloin butt
Ribeye; Loin eye
Brisket
Brisket
Tenderloin; filet mignon
Knuckle; Sirloin tip
Flank
Top (inside) round
Eye of round
Boneless short ribs
Chuck tender
Tri-tip
Shoulder Tender
Outside chuck
Ranch Cut
Muscle Musician
• http://vimeo.com/47875656