Most people look at muscle groups as simple structures.
This couldn't be further from the truth! A muscle is one of the most complex
organs in the human body. It contains thousands and thousands of cells,
organelles, regulators, and protective barriers. The following will break down
this structure from its most vital unit, to the units that surround it. In the
end you will understand such questions as
1. Why is a muscle striated?
2. How does a muscle contract?
3. What fuels contraction?
4. Why would a muscle be flat some days and full others?
5. What are the inner workings of a muscle cell and what can I manipulate for
growth?
Overall however, you will begin to view these creations as
complex structures, and be able to translate this knowledge to extreme growth!
Further I will refer back to this article throughout the entire anatomy section,
so it is important that you grasp these concepts. In fact the anatomy section
will essentially explain how to manipulate everything you read about today.
Therefore this article goes way beyond today, and
expounds into countless other anatomical subjects!
Skeletal Muscle
Muscle tissue is unique in that
it has the ability to contract
and can perform mechanical
work. There are actually three distinctive classifications of this tissue. The
first is Smooth muscle (digestive system, veins, muscular arteries), the second
is Cardiac muscle (the heart) and finally what you came here today to hear
about, Skeletal Muscle! This type of tissue has several significant
characteristics. It can produce extreme force (mass xs acceleration), is meant
to move and stabilize our skeleton, is mainly controlled voluntarily and is
striated! Each of these characteristics will be covered in detail.
We will first cover the main
unit of this tissue, which is called a muscle cell or muscle fiber.
These cells are the workhorses of muscle groups and are the main target for
bodybuilders as far as growth is concerned. What I will do in this article is
break down the anatomy of these fibers. In addition to this, I have written a
three-part article on essentially every subtype of muscle fiber and how to force
these subtypes into growth. That article will not be of optimal benefit if you
do not understand the inner workings of these cells. As a description, muscle
fibers are long and threadlike. In fact, if you were to get a close look at
your biceps you would see that it contained thousands and thousands of these
threads lying parallel to each other. These fibers are longer than any other
cell in our bodies. With their importance in mind, lets break down every
element of a muscle cell.
The Muscle Cell Membrane
Everyone has a front door to their house, and this may
expound to a fence, a garage, and even an alarm system. These tools keep
thieves, strangers, animals and a host of other threats out of your house. They
also help to keep your valuable china, jewelry, barbells, squat rack (hey I had
to mention my prized possession!) safely inside. Moreover, you have control
over who you allow in through your doors, which in scientific terms, makes your
house " selectively permeable. " In that you " select " who is allowed in. It
just so happens that our muscle cells also have a protective mechanism. This is
called a cell membrane, or more specifically the Sarcolema.
The Sarcolema is an extremely thin (you need a microscope
to see how thin!) flexible and elastic substance that completely covers the
entire muscle fiber. Think of it as the saran rap placed around the cookies on
your kitchen counter (those are for guests right?). The closer you look the
more complex this structure looks. The first job of the membrane is to maintain
the wholeness of the cell (1). If for some reason this protective sheathe were
damaged to extreme levels, then the contents within would escape and the cell
would die. Therefore it keeps every vital content inside. Again, think of
this as a locked door keeping your precious valuables safely inside your house.
Further it acts as a gateway through which substances (i.e. amino acids) can
enter and leave the cell. This is selectively permeable, which means it
controls what can enter or leave.
How and Why is it Selectively
Permeable?
That is an excellent question! It has to do with its make up, which is about 50
percent proteins, 48 percent lipids (mostly phospholipids) with a dash of carbs.
Lipids are fatty substances and occur in two layers. The proteins that are in
the bilayer float within the lipid. This is important to carrying out their
functions. Picture a double layered frosting on a cake with m & m's on top. If
your significant other isn't a great cook (don’t tell her that!) then the
frosting has a watery texture and the m & m's float across it when you carry
your plate to the table. I used that example because I'm dieting and cake
sounds fantastic! A better way to describe it would be to think of the proteins
as floating ice bergs on a sea of lipids.
In the picture above, the white bilayer is made
up of lipids and the red and purple structures are proteins that serve as pores,
transporters and receptors!
Lipids happen to be very insoluble to water,
which is to say water cannot pass through. The lipid makeup of the membrane
keeps vital watery contents inside of the cell and separates them from the
watery environment outside of the cell. This is one method of selective
permeability (water has to be transported in). The proteins have several jobs
and as stated can move from one side of the membrane to the other. The first
job is simple, protein molecules can serve as pores that allow nutrients inside
of the cellular environment. This type of protein is called a glyco-protein
because it is part sugar and part protein. These also act as transporters,
which is to say that they bind themselves to a substance and carry it across the
membrane much like a ferry takes a car across a lake. Glyo-proteins are very
selective however, and only allow certain substances to pass or be transported
through the membrane. They also serve as " receptors. " These are able to bind
with only " specific " molecules such as hormones or a nutrient that is vital to
cellular maintenance. As a quick overview the cell membrane does the following:
1. Keeps vital components
inside of the muscle cell, such as glycogen, atp, mitochondria, myofibrils and
everything we will cover in the following paragraphs.
2. It also transports waste
build up from the contractions of muscle fibers out of the cell.
3. Is permeable to nutrients
that are vital to the life, maintenance and repair of our muscle cells. Such
substances are amino acids, carbohydrate molecules ( glycogen stores ), oxygen
etc.
Can You Manipulate The Uptake
of Muscle Building Nutrients such as Glucose and Amino Acids?
Absolutely, but first I will
explain a bit more about how the cell is selectively permeable. First I
mentioned that lipids are not soluble to many molecules such as water. What is
soluble can pass through the lipids however. I also explained that a membrane
had pores, receptors and transporters all made out of protein molecules. This
is where nutrients that cannot pass through the lipids enter into the muscle
cell in a regulatory fashion. I must stress again, that the proteins
responsible for regulation will only allow certain molecules to pass through the
membrane. I will cover how the main processes occur:
Diffusion - This process is very
easy to understand. It simply means that molecules move towards areas of less
concentration. So lets say you finished working out and your muscle cells are
dehydrated. The water outside of the cells in higher levels of concentration
will move toward the areas of lower concentration until a balance has been
reached! You can test this out right now using a cup of water and sugar. Place
a spoonful of sugar in a plain cup of water. What happens? It starts to move
toward the water with a lower concentration of sugar right? It continues busily
moving until a balance has been sought. The same method of diffusion works with
the pores in our cell membranes. As soon as a balance occurs, diffusion ends.
Waste produces will also diffuse out of the muscle fiber, when concentrations
increase. And if a substance is fat soluble it can diffuse through the lipids.
Facilitated Diffusion - This is diffusion that is assisted
by protein transports. When a needed nutrient is low in the muscle cell
environment and it cannot pass through the pores, then it must be transported.
This is similar to the above process except that it needs a boat to get across
the plasma membrane and into the cell environment. Following a workout, when
glucose concentrations are low, and you down a high carb drink, the glucose in
your blood stream has a high concentration. This stimulates insulin to be
secreted which thereby increases receptors known as Glucose 4 proteins to be
translocated to the cellular surface. Further, muscular contraction will also
stimulate these receptors. The combination of greater concentration of GLUT-4
receptors and the fact that the concentration gradient in the cell is low will
cause the glucose to rapidly enter the cytoplasm.
Facilitated diffusion is shown below. The green nutrients
are insoluble to lipids, they therefore must move across the membrane in a
transported manner. The purple protein transporters as you can see take the
nutrients, carry them across the membrane and then release them inside of the
cell environment!
One surefire way to manipulate the permeability of a cell
membrane is to workout. It damages the sarcolema and makes it more permeable.
This facilitates the entering in of several anabolic agents such as hormones,
glucose, amino acids and other nutrients. Also when you train, waste products
build up in the cell and precious nutrients such as glucose are depleted.
Therefore your muscles will suck up glucose at a much higher rate! It just so
happens that glucose is vital for recovery and I will further expound on this in
my muscle fiber article. This is one of the reasons that sugar is unlikely to
be stored as fat following a workout. Because your muscle concentration levels
are so low and permeability is increased big time! This is a second way is to
increase your hormone levels.
For example, when insulin binds itself with the receptors
on your cell membrane( 1 ), a host of protein transporters fly out to the top of
the membrane, making it way, way more permeable! Therefore this increases the
uptake of amino acids, glucose and even magnesium! Which equals immediate
growth! Growth hormone is also a major player and testosterone is the grand
daddy of them all. Again, following a workout, when a muscle is damaged, repair
is the primary focus and receptors are extremely sensitive to hormones, which is
why you will want to take advantage of the situation. It is for this reason,
that future issues of the magazine will discuss how you can naturally improve
specific hormone production! I will also stress how to further improve
sensitivity to these hormones!
Journey Inside Of The Muscle
Fiber!
I just covered what a muscle fibers " gateway " was, but
what exactly do you find once you have gained access? You find the cells
Cytoplasm, which in regards to a muscle cell is called the Sarcoplasm. This is
literally everything inside of the plasma membrane (cell membrane, or sarcolema
) aside from the nucleus ( which will be discussed in further articles ). Using
your residence as an example again, the Sarcoplasm is essentially the interior
of your house and everything contained in it. These contents can be broken
down into two clear areas. In order to explain this, I will compare a muscle
fiber to a cigar. When you cut a cigar what do you see? Tiny threads of
tobacco running the length of it correct? It is the same concept here, if you
look into a muscle fiber, it will appear to be stuffed with little threads.
These threads are called myofibrils and are a prime target for growth! They
contain the elements that allow our muscles to contract. The second aspect we
will discuss is what lies between these tiny threads. The muscle fiber is moist
like the cigar. This moisture is similar to the texture of the gel you use for
hair styling, and you will find it between and all around the myofibrils. It is
called the cells " Cytosol " and has some very, very important features, vital
to your success in this sport!
Cytosol Explained
The cytosol is the intracellular fluid inside of the
muscle fiber. This structure is extremely busy! It takes raw materials from
the outside of the cell (passed through the cell membrane), then stores or
converts those materials to useable energy. In other words this transparent gel
contains such foods as amino acids for maintenance and repair, and glycogen (a
complex carbohydrate) for energy. You see a muscle fiber must have a fuel
source in order to contract. This is why the cytosol also has tiny organs
called organelles, or microscopic organs. Perhaps the most significant of these
is mitochondria, because it converts carbohydrates, and fats into ATP, which is
our muscle cell's main energy currency (fuel).
Have you every wondered why your muscles are flat some
days and on others full? As you recall the cytosol contains stored
carbohydrates. Guess what? For every carbohydrate gram you store an additional
2.7 grams of water! Whenever you consume plenty of carbs, your cytosol becomes
saturated with them, and each carb pulls nearly 3 grams of water into this jelly
environment! Therefore your muscles fill up like a balloon! You can always
tell how anabolic your nutrition is by how full your muscle cells are. Usually
on a cut, they become flat and your skin doesn't look very tight. This causes
what I call, dieting blues. Because many athletes feel they are losing muscle,
when in fact they are simply low on carbohydrate stores in their cytosol.
Just think about it....What is more impressive, a balloon
filled up tightly with water, or one that is only half full? Since
carbohydrates pull water inside of the cell, bodybuilders can use this to draw
extra-cellular water that is outside of the muscle cell, into the cytosol before
a contest or photo shoot. I'd tell you all the secrets to doing this now, but
that would ruin my article on pre-contest carb manipulation! I know there are a
lot of panicking dieters out there. Next time your training partner starts to
panic, just tell him that he does not have enough glycogen in his cytosol.
Let me also add, that these macronutrient (food) stores in
the cytoplasm are very important to both training and growth! As I stated, your
muscles use ATP as their fuel for both growth processes and contraction.
Macronutrients are the main source of raw materials used to form ATP.
Therefore, if your carb stores are low, your energy will suffer in the weight
room.
Note:
To place a functional bearing on what the cytosol and
mitochondria do. I have included detailed useful descriptions about them in the
muscle fiber 1-3 series. The information here, combined with that series will
show you just how vital these are!
Also inside of the intracellular fluid is the Mitochondria
(organelles). These are our cellular furnaces! They take the raw material
inside of the cell and turn it into ATP. These tiny organs look like jelly
beans spread throughout the cytosol. Let me just say this: " Your body depends
on Mitochondria to produce ATP. If you cannot produce enough ATP you will lower
energy levels in the weight room and eventually not be able to gain any more
muscle! The opposite also holds true!
Myofibrils
These are the threadlike tissue
spread throughout a muscle fibers sarcoplasm. They are the contractile units of
our muscles, which just shows their importance. A bodybuilder will spend most
of his/her time stimulating growth and increasing the number of myofibrils in
their cells! The reason for this, is that they comprise approximately 80
percent of the volume of a muscle fiber!
Using the picture as a reference, what do you notice about
the myofibrils? They are made up of a series of smaller segments right!? You
see those white lines? One white line (actually the black line between the
white lines) to another makes up one segment of a myofibril and these are known
as " sarcomeres. " A sarcomere literally means " muscle segment. " Therefore
myofibrils, which are the functional units of skeletal muscle are made up of a
chain of sarcomere units laid end to end, or " in series. " This is actually
very important and is one of the reasons why a person can build up the lower
sections of a muscle group, such as the lower biceps. I will cover this in
greater detail in my
physiological aspects of bodybuilding article.
What else do you notice? A series of dark and white bands
correct? These dark and light bands make up each sarcomere and as they spread
across a myofibril, they give it the appearance of being striped or striated, as
we bodybuilders like to refer to it! The organized stripes that you are viewing
are the main elements of each muscle segment, and are responsible for
contraction (I will discuss how shortly)! They are actually two specific types
of protein filaments or threads known as " myofilaments. " Here is a closer
picture (this is simply the myofibril above magnified) of what they look like:
What we will do is dissect this particular structure. You
can see several labels on this myofibril. There are Z-lines, I bands, A bands,
M lines, actin and myosin. These can look confusing, but they are simply "
labels " or " names " for the regions of each sarcomere. As I stated, there are
two specific protein filaments that make up the sarcomeres and are responsible
for contraction (4). The first is the blue " thin filament " called actin and
the thicker (red) filament is called myosin. Again, these are protein threads.
The A band is the darker section of the sarcomeres and this is where the thick
myosin filaments extend all the way through and the thin actin filaments extend
partway across it. Therefore the A band is where the actin overlaps the myosin
proteins. The A actually stands for Anisotropic, which in German means that it
appear darker as more light is absorbed. As German scientists looked through
the microscope, this is what they noted and the name reflects this.
The I band is where only the actin proteins go across and
meet each other, but where no thick filaments are found. In German, I stands for
Isotropic and means that the area appears to be lighter as more light can go
through it. The Z-line is simply a thin protein sheet that connects the actin
filaments to each other and also connects each sarcomere to each other. The Z
stands for Zwishensheibe for ‘between disk.’ A sarcomere is everything between
successive Z-Lines. The H-Zone is the spot on the A band, in which the actin
proteins do not overlap the myosin proteins. The H stands for Hellerscheibe,
which is German for clear disk. Finally the M line is darker because tiny
protein strands connect one thick myosin filament to another. The M stands for
Mitelsheibe for middle disk. To break this down into two simple sentences. The
A band is darker because actin and myosin filaments overlap each other and the I
band is lighter because they do not overlap each other, in turn giving a muscle
fiber it's striated appearance. Furthermore all the seemingly confusing names
for regions of a myofibril/sarcomere are simply labels for those regions based
on how German scientists saw these regions under the microscope.
How A Muscle Contracts
If we get a closer look at the contractile proteins (actin
and myosin) of the myofibrils we can see that the process of contraction flows
very nicely.
When magnified you will notice that the myosin filaments
(thick) have tiny heads protruding out of them. These heads make contact with
the actin filaments. Think of them as oars coming out of a boat and the actin
protein as water. When your brain sends the signal for the muscle to contract,
the myosin heads pull the actin proteins closer together, which in turn pulls
the z-lines closer together, which in turn shortens or contracts the sarcomeres,
and finally when thousands of these sarcomeres are contracting in a muscle
group, the whole muscle shortens and pulls the bone that it is attached to in a
the desired direction. Next time you flex your biceps, realize that your
myosin heads are pulling your actin filaments closer together, which shortens
the sarcomeres. Remember, sarcomeres in series are what make up a myofibril.
Myofibrils are the main unit of a muscle fiber.
Note: For more detail on initiation of muscular
contraction, see Wilson (2003, Is The All
Or None Principle Applicable to An Entire Muscle?)
In order to fuel contractions, the myosin needs ATP and
calcium. You see the actin proteins have binding sites that the myosin heads
bind with to slide the actin molecules closer to each other. The problem is
that these binding sites are covered or hidden by a protein called tropomyosin.
In order to shift the tropomyosin to reveal the binding sites, calcium must be
released from the muscle cells calcium storage bin( known as the sarcoplasmic
reticulum). This calcium then binds with a protein associated with the
tropomysosin known as troponin, which causes the former molecule to be removed
from its place on the binding site. Following this the actin can bind with the
myosin heads by using ATP as its fuel. The binding of Ca++ serves as the
molecular switch which not only removes the binding site, but triggers the
breakdown of ATP to ADP + Pi. This process is called the " sliding filament "
theory and was first analyzed by a man named Hugh E. Huxley (1957). It is the
number one accepted theory today! Here is a review of what happens when a
Muscle Contracts:
A. In a relaxed state, the thin
filaments of the actin are separated.
B.
When The Muscle is contracting, the thin actin filaments are sliding toward each
other as the thick myosin filaments stay stationary . This causes the distance
between the Z lines to decrease.
C.
In a maximally
contracted state, the thin filaments have overlapped one another and the
sarcomeres have shortened to their maximum amount. The H zone has disappeared,
and the I band has decreased in size dramatically.
The particular adaptation that
bodybuilders seek is an increase in muscular size. In order to adapt to
contractions a muscle fiber can increase the number of myofibrils it has,
thereby increasing its contraction ability and the fibers overall size.
Moreover they can add sarcomeres in series to the myofibril, which would
lengthen it. All of these adaptations occur when you are lifting for " muscular
hypertrophy. " This type of training is specific! In fact you have three
different muscle fiber subtypes and each must be trained differently in order to
stimulate hypertrophy. This is why I have dedicated three articles to this
subject entitled Muscle Fibers - An in Depth Analysis 1-3.
Veins,
Capillaries
and
Arteries!
Muscular contraction requires the energy
contained within the ATP molecule.
In
order
to
synthesize ATP, vital nutrients such as carbohydrates are required, as well as
the terminal electron acceptor oxygen.
Further, metabolic
waste
products
from
muscular
contraction as well as other cellular actions must be
cleared
out
of
the
cell,
in
order
to
maintain
proper function.
Thus,
muscles
need
a
rich
blood
supply
to
deliver
these
nutrients.
This
process
is
carried
out
by
blood
vessels.
In
a
general
sense,
a
vessel
is
defined
as
a
hollow
utensil
for
carrying
something:
a
cup,
a
bucket,
a
tube.
Blood
vessels,
then,
are
hollow
utensils
for
carrying
blood.
The
largest
of
these
are
the
arteries.
They
are
the
largest
because
they
carry
blood
directly
from
the
heart
to
the
tissues and therefore must
withstand
the
highest
pressures.
Capillaries
are
of
prime
concern
here,
as
they
are
plentiful
in
muscle
tissue.
Think
of
capillaries
as
miniature
vessels.
Once
the
arteries
carry
their
blood
to
the
capillaries
an
exchange
occurs,
in
nutrients
and
oxygen
diffuse from
the
red
blood
cells
into
the
surrounding
muscle
tissue
and
the
blood
cells
in
the
capillaries
then
pick
up
the
waste
such
as
carbon
dioxide. In actuality this process occurs due to concentration and
pressure gradients. For example, the metabolic bi product of energy
production via aerobic metabolism is carbon dioxide. As blood courses
through the capillaries, the gradient favors this C02 to diffuse from its
higher concentration in the tissue, to its lower gradient in the capillaries.
So to, the oxygen in the capillaries favors its movement toward the tissue until
equilibrium is reached.
Veins
are
the
opposite
of
arteries
in
that
they
carry
blood
back
to
the
heart.
Ever
wonder
why
they
have
that
cool
greenish,
blue
color,
that
adds
an
incredible
freakiness
to
the
outer
appearance
of
your
muscles?
It
is
due
to
the
fact
that
veins
in the systemic circuit carry
deoxygenated blood. Hemoglobin, the molecule which carries 02,
assumes a more reddish hue when bound to this molecule, and when unbound it
assumes the color coursing through your veins.
Veins are very elastic to accommodate for blood flow and
actually have muscle in the middle of their structure. When forced to
accommodate for greater blood flows veins become stronger and can handle more
blood volume. Moreover the muscle
which is in the middle of the veins can be hypertrophied( 1 ) by increased
circulatory needs, therefore
enhancing
the
size
of
your
veins! Anyone
who
emphasizes
extreme
blood
pumps
will
increase
the
size
and
strength
of
their
veins.
Capillaries
connect
a
muscle
to
our
cardiovascular
system.
They
do
contribute
to
the
size
of
a
muscle
as
well.
A
increased
blood
demand
will
actually
cause
muscle
capillarization.
Therefore,
exercises
such
as
supersets,
flexing
between
sets
and
anything
that
increases
the
blood
pump
will
increase
vascularity, muscle size and your ability to recover faster between sets!
I say it will improve recovery for obvious reasons. You will have a
greater ability to deliver precious nutrients and carry waste products outside
of your muscles.
Connective
Tissue
-
The
Stuff
That
Puts
Everything
Together!
We
now
have
a
clear
anatomical
understanding
of
the
functional
unit
of
a
muscle,
which
is
the
muscle
fiber.
What
is
important
to
grasp
is
that
most
muscles
contain
hundreds
and
thousands
of
these
fibers.
Which
means
that
the
body
must
arrange
them
in
an
organized
fashion
in
order
to
form
a
working
muscle
group,
such
as
the
biceps,
pecs
and
quads!
Further,
we
need
to
understand
the
function
of
a
muscle
group,
which
essentially
is
to
stabilize
and
move
our
skeletal
system.
Therefore,
once
these
muscle
cells
are
organized
in
a
functional
pattern
they
need
to
be
attached
or
indirectly
attached
to
the
bone
they
are
responsible
to
move.
In
order
to
accomplish
these
important
aspects
that
allow
us
to
freely
walk,
talk,
run
and
eat
pizza
(
like
I
said
I'm
dieting!
)
our
body
uses
connective
tissue
called
"
fascia.
"
An ndividual
muscle
is
separated
from
neighboring
muscles
and
held
into
place
or
position
by
layers
of
this
fascia.
In
addition
to
holding
a
muscle
in
place,
this
connective
tissue
(
called
connective
because
it
literally
binds
and
connects
structures
)
also
extends
away
from
the
muscle
fibers
and
protrudes
into
a
cord
like
shape,
attaching
the
muscle
group
to
the
bone.
This
extension
of
the
fascia
is
called
a
"
tendon.
"
The
word
fascia
means
bundle
or
band
and
it
does
exactly
that,
it
bands
tissues
and
organs
together
in
a
collective
manner.
On
a
whole
it
is
a
very
fibrous, course,
flexible,
and
strong
tissue.
Just
to
show
you
how
strong,
a
tendon,
can
resist
8,
600
to
18,
000
pounds
per
square
inch!
(
2
)
That
boggles
the
mind
does
it
not?
As
does
the
entire
human
body!
It
is
without
a
doubt
the
most
amazing
machine
ever
created!
Breakdown
of
Connective
Tissues
and
How
A
Muscle
Fiber
Is
Organized
There
are
two
types
of
fascia.
The
first
is
called
superficial
fascia
and
it
lies
immediately
underneath
the
skin.
This
is
the
tissue
that
holds
water
and
fat.
The
reason
why
I
mention
it,
is
obvious.
From
an
anatomical
standpoint
you
can
see
why
fat
obstructs
your
muscles
form
showing
clearly.
You
have
to
first
burn
the
fat
from
within
the
superficial
fascia.
What
we
are
concerned
with
is
the
deep
fascia,
which
holds
the
muscles
together.
Here
is
an
illustration
of
a
diced
open
muscle
and
all
of
its
layers:
As
You
can
see
the
outer
most
layer
of
the
muscle
is
the
deep
fascia.
Again
this
is
very
dense
tissue
and
is
strong
from
every
direction
to
provide
the
muscle
fibers
with
the
absolute
highest
level
of
protection
and
mobility.
You
can
also
see
that
the
deep
fascia
extends
out
into
a
cord
like
arrangement
which
is
the
tendon.
The
tendon
attaches
to
the
bone.
What
I
am
going
to
tell
you
is
very
important!
The
part
of
the
muscle
that
attaches
to
the
more
fixated
bone
is
the
origin
of
a
muscle
group,
and
the
part
of
the
muscle
that
attaches
to
the
more
moveable
bone
is
called
the
insertion
point.
This
will
be
elaborated
on
this
in
many
articles.
I
will
now
break
down
the
above
picture
from
the
smallest
unit
to
the
largest.
1.
Muscle
Fiber
-
This
is
the
functional
cell
of
a
muscle
group.
2.
Endomysium
(
Sheath
)
-
Every
muscle
fiber
is
wrapped
with
a
thin
sheath
or
casing
of
connective
tissue.
This
surrounds
each
muscle
fiber,
protects
and
separates
it
from
neighboring
muscle
fibers(
3
).
Think
of
the
endomysium
as
the
casing
on
a
pen.
Inside
you
have
the
inch
filled
plastic
containing
ink.
It
is
the
functional
part
of
the
pin,
but
the
ruff
plastic
around
it
simply
protects
the
ink
inside
and
makes
the
pen
more
functional
for
you.
If
the
pen
didn't
have
this,
then
the
thin
plastic
would
break
in
your
book
bag
or
brief
case
and
probably
get
all
over
your
clothes!
This
is
essentially
the
same
principle.
The
Endomysium
is
a
sheath
for
the
muscle
fiber
or
container.
It
is
very
thin
and
hugs
the
fiber. However, there are other functions it is involved in. For
example, it serves to insulate the muscle fiber, such that electrical
impulses are contained within it( see Wilson, 2004 - Is the All Or None
Principle Applicable to An Entire Muscle Group? )
3. Fascicles
(
bundles
)
-
Fascicles
are
bundles
of
muscle
fibers
encased
in
their endomysiums.
If
I
picked
up
a
stack
of
pens
and
held
them
in
a
bundle,
they
would
look
like
fascicles.
This
term
literally
means
bundles,
so
these
two
words
should
stick
together
and
you
shouldn't
have
a
problem
envisioning
them.
I
will
come
back
to
this
over
and
over,
but
a
muscle's
overall
ability
and
function
is
determined
by
the
arrangement
of
these
fascicles.
Just
hold
on
to
that
and
I
will
address
it
again.
4.
Perimysium
-
The
perimysium
is
to
the
fascicles
what
the
endomysium
is
to
the
muscle
fiber.
In
other
words
each
bundle
of
fascicles
is
wrapped
by
a
strong,
dense
tissue
called
the
perimysium.
By
the
way,
Peri
means
around!
So
think
of
this
connective
tissue
as
simply
rapping
around
and
protecting
and
organizing
the
fascicles
so
they
can
work
together.
5.
Epimysium
-
Remember
a
fascicle
is
a
bundle
of
muscle
fibers
bound
up
in
the perimysium.
In
order
to
form
a
muscle
group
you
need
several
bundles
to
work
together!
Therefore
we
now
take
the
fascicles
wrapped
in
perimysium,
bundle
them
up
and
wrap
them
in
an
even
stronger
and
courser
connective
tissue
called
Epimysium.
Epi
means
to
surround.
So
this
thick
layer
of
connective
tissue
"
surrounds
"
and
binds
together
all
of
the
bundles
of
muscle
fibers
called
fascicles.
6.
Finally
the
whole
thing
is
covered
by
deep
fascia
which
holds
the
muscle
fiber
in
place.
This
as
shown
by
the
picture
above
extends
out
to
form
the
tendon
which
is
attached
to
the
bone.
Fascicle
Arrangements
=
Biceps,
Delts
etc!
The
arrangement
of
the
fascicles(
within
a
muscle
group
)
will
determine
the
overall
shape
and
functional
capabilities
of
the
muscle
group.
Here
is
a
list
of
the
main
muscle
group
"
types
"
you
will
find
in
the
human
body.
1.
Parallel
-
The
name
says
it
all!
The
fascicles(
which
are
bundles
of
muscle
fibers!
)
run
parallel
to
each other.
They
begin
and
end
at
one
tendon
to
another.
The
biceps
are
a
perfect
example
of
a
parallel
arrangement
of
fascicles.
They
are
side
by
side
and
terminate
from
insertion
to origin.
What
do
you
notice
as
far
as
function
in
muscles
such
as
the
biceps?
They
have
a
very
long
range
of
motion
correct? The reason why they have such a great range of motion is due to
the length of the muscle group. You see a muscle can shorten to about 70
percent of its resting length when contracted and lengthen to about 130 percent
of it resting length. Therefore the longer and closer to being parallel
the muscle is the greater its range of motion will be.
2.
Pennate
-
The
word
Penna
actually
means
feather.
Pennate
muscles
literally
look
like
feathers!
In
a
parallel
arrangement
the
fascicles
are
long
and
run
between
the
tendons.
In
a
pennate arrangement
the
fascicles
are
very
short
and
attach
obliquely
to
the
tendon
that
runs
the
length
of
the
muscle
group.
Obliquely
essentially
means slanted
and
to
the
side.
Imagine
the
tendon
as
being
the
shaft
of
a
feather,
and
the
fascicles
being
the
barbs
that
protrude
out
of
the
shaft.
There
are
three
main
subtypes.
The
first
is
unipennate
(
one
)
in
which
the
fascicles
insert
into
only
one
side
of
the
tendon.
When
they
insert
into
opposite
sides
or
both
sides
they
are
known
as
bipennate
(
bi
meaning
two
).
The
third
is
multipennate,
which
resembles
many
feathers
side
by
side,
all
inserted
into
one
large
tendon.
The
best
example
of
this
is
the
deltoid
muscle!
What
is
one
thing
that
stands
out
about
the
deltoid
and
rectus
femoris
muscles?
They
are
strong
right!?
This
is
because
these
stocky
muscles
can
carry
the
most
muscle
fibers.
Think
about
it,
the
pennate
arrangement
allows
fascicles
to
pack
themselves
in
all
along
the
sides
of
the
tendon,
where
a
parallel
muscle
does
not. However range of motion is lessened compared to parallel
arrangements.
3.
Convergent
-
In
this
type
of
arrangement
the
muscle
fibers
spread
out
over
a
wide
area
but
they
all
converge
or join
together
into
one
attachment
site.
The
muscle
fibers
literally
spread
out
like
fan!
One
muscle
that
fits
the
bill
here
is
the
pectoralis.
The
most
prominent
feature
of
a
convergent
muscle
is
its
versatility!
The
reason
for
this,
is
that
different
portions
of
this
muscle
can
pull
in
different
directions!
A
convergent
muscle
has
versatility,
because
the
stimulation
of
only
one
portion
of
the
muscle
can
change
the
direction
of
pull.
However,
when
the
entire
muscle
contracts,
its
fibers
do
not
pull
as
hard
on
the
attachment
site
as
would
a
parallel
muscle
of
the
same
size.
The
reason
is
that
the
convergent
muscle
fibers
pull
in
different
directions
rather
than
all
pulling
in
the
same
direction.
Conclusion
There
was
a
tremendous
amount
of
information
presented
today.
In
order
to
enhance
your
comprehension
I
will
constantly
refer
back
to
the
principles
in
this
article
and
re-explain
them
throughout
the
anatomy
section!
Before
I
leave
however
I
would
like
you
to
know
the
real
reason
why
I
wrote
this
article.....You
see,
I
believe
that
you
are
the
one!
Sincerely
Jacob
Wilson
jwilson@abcbodybuilding.com
President
Abcbodybuilding / Co-Editor of The Journal of HYPERplasia Research
References
1.
Frank
Netter,
Atlas
of
Human
Anatomy
CIBA-GEIGY
1989.
ISBN
0-914168-19-3
2.
Hollinshead
and
Jenkins
1986
3.
Harold
Ellis,
Bari
Logan,
Adrian
Dixon,
Human
Cross-Sectional
Anatomy
Butterworth
Heinemann,
1991.
ISBN
0-7506-1241-X
4.
Man-Chung
Han,
Chu-Wan
Kim
Sectional
Human
Anatomy
©
the
authors,
1989.
ISBN
0-89640-165-0
5.
Gray's
Anatomy
:
The
Anatomical
Basis
of
Medicine
and
Surgery
(British
Edition.
38th
Ed);
Henry
Gray,
et
al;
Hardcover
