The Muscular System
An Overview:
The human body is made up of several main
systems, one of which is the muscular system.
They are responsible for more than 40 percent of a
person's total body weight. These muscles are
controlled by the nervous system.
Some are involuntarily controlled, meaning they
contract and relax without thought.
Other muscles are voluntarily controlled, meaning
that we must make them contract and relax.
There are a few major components of the
muscular system.
In this section you will need to understand how muscles work in
different physical activities. To show your understanding you will need
to know the major muscle groups, the types of muscle and how they
attach to the skeleton and finally how these muscles create
movement.
Muscles to remember:
pectorals
(Skeletal muscles)
trapezius
deltoids
abdominals
latisimus dorsi
triceps
biceps
gluteus
maximus
(gluteals)
hamstrings
gastrocnemius
quadriceps
3 TYPES OF MUSCLE
Voluntary (Skeletal muscle)
- These muscles make up the majority of the muscle amount in
your body and help to give your body its shape.
- They are attached to your skeleton by the tendons.
-They are called voluntary because it takes a conscious
thought process for them to contract and therefore create
movement.
Cardiac (Heart muscle)
- This is also a form of involuntary muscle.
- They ensure that the heart works automatically and
constantly.
-The shape of the muscle is designed to transmit electric
message quickly so to keep the heart working in an ordered
fashion and react to exercise or rest.
Involuntary (Smooth muscle)
- It is not possible to consciously control these muscles.
- They are essential in maintaining the ‘working body.’
- They are found in the in the walls of your arteries, blood
vessels and intestines creating dilation and constriction which
forces blood, food etc to move around in your body.
MUSCLE ATTACHMENT
-A tendon is a very
strong, non-elastic
cord that joins the
muscle to the bone.
- Here you can see the
tendon attaching the
bicep and tricep to the
humerus.
-The bone (radius and
ulna) is pulled by the
tendon when the
muscle contracts.
THE ACTIONS OF MUSCLES
Muscles are designed to contract, therefore they can only pull and not push.
Therefore muscles always work in pairs, so that contractions of one muscle
moves the joint in one direction, while contraction of the other muscle moves it
in the opposite direction.
-For example, the contraction of the biceps bends the elbow, while the
contraction of the triceps straightens the elbow.
ORIGIN AND INSERTION
Look at this diagram again. The terms origin and insertion are used to describe
where movement is inititiated from and the point at where the movement will
begin.
The diagram shows a bending
elbow.
The origin depicts the end of
the muscle that is attached to
the fixed bone.
Insertion describes the end of
the muscle that is attached to
the bone that moves.
TYPES OF MUSCLE ACTION
l
PRIME MOVERS (AGONISTS)
- Agonists are the muscles which work to create motion.
- It is the muscle that initially contracts to create a movement.
ANTAGONISTS
-These are the opposing muscles to the agonists.
-They relax to allow a movement to take place.
SYNERGISTS
-Synergistic muscles are those which aid in a movement, but they are
not meant to be the main action causing muscle for the desired
movement.
- Eg. a perfect example of this relationship is the Hamstring
group. The hamstrings are designed to assist with hip extension, but
the primary mover for hip extension are the Glutes.
Using this picture again, describe how the
man raises his arm. Include the terminology
that we have just covered.
This picture shows a man raising his forearm by bending at
the elbow. This occurs due to an agonistic movement
(contraction) by the bicep and antagonistic response
(relaxation) by the tricep. The point of origin for this
movement is at the top of the humerus by the shoulder
joint, and the point of insertion is at the base of the
humerus at the elbow joint.
What is this skeleton doing?
Which is the prime mover involved in raising his leg?
Which is the antagonistic muscle during this action?
When the other leg rises to take the next
step, this leg lowers to the ground, describe
this movement in relation to agonist and
antagonistic muscles.
Where is the point of origin and insertion
for this movement?