Muscles

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Muscles
Muscles can be divided into three main categories

• Skeletal
• Smooth
• Cardiac

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Skeletal Muscle
Skeletal or voluntary muscles work under our
control. They make our bodies move and allow us
to perform every day activities and to take part
in sport.
Skeletal/Voluntary Muscle (also known as
striated)
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Smooth Muscle
Smooth or involuntary muscles work automatically
and our not under our conscious control. They
work our internal organs such as the stomach, gut
and bladder.
Smooth Muscle
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Cardiac Muscle
Cardiac or Heart muscle is a very special type of
involuntary muscle. It is found only in the heart
and contracts regularly, continuously and without
tiring. It works automatically under constant
nervous and chemical control.
Cardiac Muscle
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Major Muscles (Front)
Pectorals
Biceps
Abdominals
Quadriceps
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Major Muscles (Back)
Deltoid
Trapezius
Triceps
Latissimus Dorsi
Gluteals
Hamstrings
Gastrocnemius
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Muscles in action
Our muscles work in different ways, there are
three main types of contraction.
Isotonic Concentric Our muscles shorten as they
contract and the ends of the muscle move closer
together.
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Isotonic Eccentric Our muscles lengthen as they
contract and the ends of the muscle move further
apart.
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Isometric Our muscles stay the same length as
they contract and there is no movement so muscle
stays the same distance apart.
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Muscles working together
Muscles can only contract NOT push therefore they
must work together across a joint in order
provide movement. Muscles have different roles
depending upon the type of movement we are
performing.
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Flexors contract to bend our joints Extensors
contract to straighten our joints Prime movers
(agonists) contract to start a
movement Antagonists relax to allow a movement
to take place Fixators contract to steady parts
of the body Synergists reduce unnecessary
movement when prime mover contracts. They can
fine tune movements
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Origin and Insertion
Our muscles are attached by Tendons to two or
more different bones.
When a muscle moves one bone usually stays fixed
and the other moves. The end of the muscle
attached to the fixed bone is called the origin.
The other end is called the insertion.
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Homework
Worksheets 14 TO 16
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How do our muscles work in pairs?
Muscles work in pairs Prime movers muscle
contracts to start the movement Antagonists
muscles relaxes, but keeps some muscle fibres
contracting to stop the prime mover from moving
the joint too hard. If this system fails it may
cause serious injury !
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