The Muscular System
of the most amazing things about the human body is the incredible range of
movement and mobility it has. This day to day activity is accomplished by our
muscles through the extraordinary and fascinating ability of converting
chemical energy, energy stored in nutrients, into mechanical energy, energy of
movement. Muscles are often views as the "machines" of the body. They
help move food from one organ to another, and carry out our physical movement.
There are three different kinds of muscles in our body: cardiac, smooth,
Cardiac muscles are involuntary and
found only in the heart. They are controlled by the lower section of the brain
called the medulla oblongata, which controls involuntary action throughout your
body. Think about how horrible it would be to have to consciously tell your
heart to beat, with the consequence of forgetting being death. What about when
you went to sleep!?! But luckily enough, the medulla oblongata does all that
Your heart cells come in long strips, each containing a single nucleus, one of
the key factors in determining which of the three classes any particular muscle
is. Located at the walls of the heart, its main function is to propel blood
into circulation. Contraction of the cardiac tissue is caused by an impulse
sent from the medulla oblongata to the SA nerve located at the right atrium
Your smooth muscles, like your
cardiovascular muscles, are involuntary. They make up your internal organs,
such as your stomach-hyper link, throat-hyper link, small
intestine-hyper link, and all the others, except your heart.
Unlike cardiovascular muscles,
smooth muscles are generally spherical, as most other human cells are, and each
contains one nucleus.
The skeletal muscles are the only
voluntary muscles of your body, and make up what we call the muscular system.
They are all the muscles that move you bones and show external movement.
Unlike either of the other two classes, skeletal muscles contain multiple
nuclei because of its large size, being in strips up to a couple of feet long.
The muscles we have in our body are
divided into three classes of muscles: cardiac, smooth, and skeletal. Usually,
when we think of muscular system we often only remember the skeletal muscles
because they make up what is recognized as the muscular system. The muscular system,
composed of over 600 muscles, comes in a variety of shapes and forms. Differences
between each muscle are recognized by location, function, structure, and the
way they are contracted.
A lever is a rigid bar on which a
given load is moved with supporting help from a fulcrum. A fulcrum is a fixed-point
on which lever can move in different ways or angles. The whole muscular system
interacts in this kind of way with the skeletal system-hyperlink. Given
a load the muscles pull the bone up or in any direction against the load. Your joints-hyperlink
usually seem to be the fulcrum on which you move the lever or bone. For
example, try lifting a book with your hand and putting your elbow on the table.
You can move the book in any direction with the help of the joints in your
elbow, and the book is lifted in any direction due to the muscles contractions.
Skeletal muscles can be broken down into groups based upon the type of movement
they portray. The movement of the muscle is based upon the type of joint
(hyperlink-Skeletal system) upon which the muscle works. Skeletal muscles
can't expand, or make themselves longer, but they can contract, or make
themselves shorter, so they generally work in pairs. One contracts, and in
doing so stretches the other, and reverses its effects on the joint. For
example, when you contract your major arm muscle, which is called the bicep, in
return the lower arm muscle, called the triceps, extends. So as you contract
one muscle the other one extends. These effects can be broken down into groups
of their own: flexors, extensors, adductors, and abductors. Flexors and
extensors become plantar flexors and dorsiflexors, respectively, when located
within either the wrist or ankle joints.
Flexors bend at the joint,
decreasing the interior angle of the joint «put graphic of this here». The
«bracius» humorous, or bicep, is a flexor of the elbow joint, bringing the fist
towards the shoulder. If a flexor appears in either the wrist or ankle joints,
it becomes a plantarflexor «try to put a graphic of this too».
Opposites of flexors, extensors
unbend at the joint, increasing the interior angle «graphic here, possibly the
same as that above». The «tracius» humorous, or tricep, is an extensor of the
elbow joint, taking the fist farther away from the shoulder. If an extensor is
found in the wrist or ankle joints, it becomes a dorsiflexor «graphic here,
again maybe the same as above».
Abductors take away from the body,
like lifting the arm to the side. Abd- means to take away, like abduct and
abdicate. Spreading out your fingers uses abductors, because you are taking
away your fingers from an imaginary line running down your arm «graphic».
Adductors, the opposites of
abductors, move toward the body. Add- means to increase or include. By lowing
an arm raised to the side, or moving your fingers together while keeping them
straight, your muscles are adducting. «graphic»
As fascinating as they are, muscles
alone can't do the job. At every joint, tendons and ligaments also help out.
Muscles wouldn't be very useful alone because they don't directly connect to
the bone, so even if they contract, they wouldn't be moving anything. Instead,
muscles are connected to tendons, when they are connected to the bones. When
the muscles contract, they pull on the tendons, which in turn pull on the
muscles, and that causes movement.
But without ligaments, that movement wouldn't be too useful because it would
not be directed movement. Without ligaments, instead of bones bending or
rotating about each other when muscles contract, they would slide by each
other. Ligaments are what hold the bones together. They connect at the ends of
muscles and keep them from slipping and sliding, and force them to bend.
Major Skeletal Muscles
The muscular body is divided into
ten different areas where muscles can be found: facial, neck, shoulder, arm,
forearm, thorax, abdomen, hip, pelvis/thigh, leg.
In the facial are one finds all the
muscles wich move the face. Orbicularis oculi-sound are the two muscles
that move the eye are. Frontalis-sound and Temporalis-sound are
the two muscles which move the forehead and sides of your head. Zygomaticus-sound
ands Masseter-sound are the two muscle that work in conjunction to move
tyoou jaw and upper lip area. Orbicularis oris-sound is the muscle which
moves your lips.
The neck area is almost entirely
moved by the sternohyoid-sound and Sternocleidomastoid-sound.
These muscles allow the neck to move your head left and right. They work with
the platysma muscle to control how far you can move your head left and right.
What allows your head to move up and down is the trapezius-sound. The
trapezius is so large that it extend down to the shoulder and thorax area. The
trapezius is a good example of how some muscles are named by their shape. the
trapezius looks just like a trapezoid.
A group of muscles all work together
to move the whole shoulder area. This group takes into account the trapezius-sound,
deltoid-sound, infraspinatus-sound, teres major-sound, and
the rhomboid major-sound. The rhomboid major is called so because its
shaped like the geometric shape of a rhombus. Along with the help of the ball
and socket joint-hyperlink in your shouder, these gruop of muscles allow
your arm to throw a softball, pick things over your head, and give your arms a
good strech early in the morning.
Most known amongst teenage weight
lifters is the arm area. The famous bicep brachii-sound is the muscle
that allows you to bring your forearm close to your body and form a huge ball
of muscle wich catches a lot of attention amongst weight lifters. The tricep
brachii-sound and brachialis-sound are the two other muscles located
in the arm region. These muscles allow a person to do push-ups!
A majority of the muscle in the
forearm help control a part of the arm. Amongst these is the Berachiodialis
major-sound, palmaris longus-sound, and Flexor carpi
radialis-sound. The name of the flexor carpi radialis is a good example of
how muscles are named by their function and location. This muscle is named carpi
because of the bones that it helps move, the carples. Also, the name of radialis
is made by the bone that its attached to, the radius.
The thorax is the set of muscles
which carrying your head, arms, stomach, and any other upper body areas. These
muscles are the trapezius-sound and latissimus dorsi-sound.
Usually, the majority of the muscles of the thorax can be damaged easly is one
dose not streach before excersice, or lifts a heave load.
The abdominal area consists of the
muscles that allows you to bend down and move your waist from side to side. The
interanl oblique-sound and external oblique-sound are the muscles
that move your body from left to right. The Transversus abdominus-sound
and Rectus abdominus-sound, along with the trapezius-sound an latissimus
dorsi-sound allow you to bend down and grab objects.
Only two muscles make up the hip
area. These are the gluteus medius-sound and gluteus maximus-sound.
Probably the laziest muscles in the whole system the gluteus set of muscles are
used only to sit down on.
An overlaping of muscles is what
makes this area so firm. The pelvis area is usualy refered to as the upper part
of the leg. Muscles like the pectineus-sound and illiopsoas-sound
, which help support the upper leg area are known as pelvic muscles. Thigh
muscles are very rich in capillaries and support the whole body. The upper
thigh muscles are abductor longus-sound, Gracilis-sound, Sartorius-sound,
and Tensor fasciae latea. The lower thigh muscles are rectus
femoris-sound, vastus lateralis-sound and medialis-sound. Located
in the back of your leg are the hamstrings-sound. These muscles help you
run, jump, and walk!
Helping the thigh region support the body is the
Leg region. These muscles like the Gastrocnemius-sound, soleus-sound,
porenius longus-sound, and Tibialis anterior-sound absorb the
impact when one walks and runs. they also give beter cordination for moving.
the thigh region trust the body forward while the leg region coordinates where
it should be thrusted and where it should stand.