GCSE Physical
Education
The Muscular System
Muscles
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There are 3 types of muscles within the muscular
system:
 Voluntary (skeletal)
 Involuntary
 Cardiac
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http://uk.youtube.com/watch?v=iat3xk9f40A
http://www.youtube.com/watch?v=TdYN7cePiRI
Video clip
Voluntary (skeletal) muscle
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Are under the control of our will
Attached to the skeleton
Made up of cylindrical fibres
Usually long and thin and found in
pairs
Involuntary muscles
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Found in the organs of our body
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Digestive, circulatory and urinary systems
Controlled by the involuntary nervous system
Made of spindle shaped fibres
Cardiac Muscle
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Found in the wall of the
heart
Involuntary
Made up of interlaced fibres,
which help the nervous
impulses, sent by the brain
to regulate our pulse and the
force of our heart beat.
It never tires (as long as it
has a good blood supply).
Structure of muscle
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Muscles are made up of
many muscle fibres, each
of which contain many
myofibrils.
These can either be slow
twitch or slow twitch.
Types of Muscle Fibre
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Slow twitch (Oxidative) Fibres
Deep red in colour
 Have a good Oxygen supply
 They contract slowly, but can work for long periods
of time without tiring.
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Fast twitch (Glycolytic) Fibres
White in colour
 A more forceful contraction, but fatigue relatively
quickly.
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Muscle Function
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The main function of skeletal muscle is to
produce movement.
Muscles are attached to the skeleton, so that
they can contract and pull on bones
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Muscles are attached to bones by tendons.
Muscles are attached at both ends
One end is called the origin, and is fixed to
something rigid.
 The other end – the insertion – is attached to the
bone that moves.
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Antagonistic pairs
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As muscles can only pull, not push, they are usually
arranged in antagonistic pairs
One muscle will bend (flex) the joint and the other will
straighten (extend) the joint.
Whilst one muscle contracts (agonist), the other relaxes
(antagonist). Allowing full movement at the joint.
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E.g the bicep contracts to flex the elbow whilst the tricep
relaxes.
This is known as an isotonic contraction
If both muscles contract together then no movement takes
place. This is known as an isometric contraction.
Antagonistic pairs
Muscle Tone
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Muscle cells are never all resting at the same time.
Some are muscles are always ready for action – this is
known as muscle tone.
One of the functions of muscle tone is that it keeps the
body primed and ready for instant action.
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Also keeps the body in an upright position
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This is called POSTURE
Our joints are held firm by the flexor and extensor
muscles both working at the same time
Major muscles of the body
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REFER- 140
MUSCLES OF THE BODY DIAGRAMS AND
HANDOUTS, USE OVERHEAD PROJECTOR AND
GET PUPILS TO FILL IN.
COPY AND FILL IN TABLE AT THE BOTTOM OF 142.
MAIN TASK – LIST THE MAJOR MUSCLE GROUPS
AND BRIEFLY DESCRIBE THEIR FUNCTION IN
RELATION TO MOVEMENTS. PLEASE USE
SPORTING EXAMPLES. PERFORM MOVEMENTS
WITH PARTNER IF NECESSARY.
THIS CAN BE DONE IN THE FORM OF A TABLE –
SPLIT INTO LOWER AND UPPER. P138-142
ANTAGONISTIC MUSCLES
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ANTAGONISTIC MUSCLES
MUSCLES CAN ONLY CONTRACT AND RELAX. THEY
CANNOT LENGHTHEN ON THEIR OWN ACCORD.THEY
HAVE TO BE PULLED BACK TO THEIR ORIGINAL LENGTH.
CONSEQUENTLY, MOST MUSCLES WORK IN PAIRS. ONE
MUSCLE PULLS IN ONE DIRECTION WHILST THE OTHER
PULLS IN THE OPPOSITE DIRECTION. WHERE SUCH
ANTAGONISTIC PAIRS ACT ACROSS A HINGE JOINT THEY
ARE CALLED EXTENSOR NAND FLEXOR MUSCLES. THE
EXTENSOR TENDS TO EXTEND OR STRAIGHTEN THE LIMB
WHILST THE FLEXOR BENDS OR FLEXES IT. ONE IS
USUALLY STRONGER THAN THE OTHER. THE BICEP IS
MUCH STRONGER THAN THE TRICEP FOR EXAMPLE.
SUMMARY OF MOVEMENTS
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TRICEPS – EXTEND THE FOREARM
BICEPS- BENDS THE ARM AT THE ELBOW
DELTOID – RAISES AND ROTATES THE ARM
PECTORALIS MAJOR – CAN EITHER DRAW THE ARM FORWARD OR ROTATE
IT.
TRAPEZIUS – COVERS THE SHOULDER BLADE AND HOLD IT IN POSITION.
IT CAN ROTATE THE SHOULDER BLADE AND MOVE THE HEAD TO THE
BACK AND THE SIDE.
GLUTEALS – (MAXIMUS) EXTENDS AND ROTATES THE THIGH AROUND
THE HIP JOINT. IT ALSO RAISES THE TRUNCK OF THE BODY.
QUADRICEPS – 4 MUSCLES STRAIGHTENS OUT THE LEG AND HOLD IT IN
POSITION WHEN STANDING
HAMSTRINGS – 3 MUSCLES FLEX THE KNEE.
GASTROCNEMIUS – EXTEND THE ANKE JOINT.
RECTUS ABDOMINUS – BENDS THE TUNCK OF THE BODY FORWARD OR TO
THE SIDE.
SARTORIUS – THE LONGEST MUSCLE IN THE BODY. IT ROTATES THE
THIGH OR RAISES IT TO THE ABDOMEN AND ALSO HELPS TO BEND THE
KNEE.
Homework
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Learn the muscles listed on pg139 of the
textbook. Finish off!