Task 2
A)
The Muscular System
B)
Function of the Muscular System:
-Movement: The skeletal muscles contract to produce body movement.
-Support and Structure: The skeletal muscles help to maintain the posture of the body.
-Heat Production: The muscles produce body heat as a by-product of muscular contraction;
which a method of maintaining body temperature.
-Storage of Glycogen: Glycogen is the source of energy most often used for exercise. It is stored
in the muscle for use in exercise.
C)
Muscle
Origin
Insertion
Function
Trapezius
-Clavicle
-Scapula
Elevation, retraction and
depression of the
shoulder girldle.
Adduction and extension
of shoulder.
Deltoid
-Base of the skull
-Cervical and
thoracic vertebrae
-Lower six thoracic
vertebrae
-All lumbar vertebrae
-Illium
-Clavicle
-Sternum
-Shoulder
Biceps Brachii
-Scapula
-Radius
Triceps Brachii
-Humerus
-Scapular
-Scapular
-Ulna
Rectus Abdominis
Obliques
-Pubis
-Ribs
-Illium
Erector Spinae
Vastus Lateralis
Vastus Medialis
Vastus Intermedius
Semimembranosus
-Sacrum
-Illium
-Vertebrae
-Illium
-Illium
-Femur
-Femur
-Femur
-Femur
-Ischium
-Sternum
-Illium
-Pubis
-Ribs
-Ribs
-Vertebrae
-Base of skull
-Femur
-Tibia
Semitendinosis
-Ishium
Bicep Femoris
Gastrocnemius
-Ishium
-Femur
-Femur
Soleus
Tibialis Anterior
-Tibia
-Tibia
Latissimus dorsi
Pectoralis Major
Teres Major
Gluteus Maximus
Rectus Femoris
-Humerus
-Humerus
-Humerus
-Humerus
-Tibia
-Tibia
-Tibia
-Tibia
-Fibula
-Tibia
-Fibula
-Tibia
-Fibula
-Calcaneus
-Calcaneus
-Tarsals
-Metatarsals
Horizontal flexion and
adduction of shoulder.
Abduction, flexion and
extension of the shoulder.
Flexion of elbow and
shoulder. Supination of
forearm.
Extension of elbow and
shoulder.
Medial rotation of the
shoulder.
Flexion of vertebrae.
Rotation of vertebrae.
Extension of the
vertebrae.
Extension of the hip.
Extension of knee.
Extension of knee.
Extension of knee.
Extension of knee.
Flexion of knee.
Flexion of knee.
Flexion of knee.
Plantarflexion of ankle
and flexion of knee.
Plantarflexion of ankle.
Dorsiflexion of ankle.
D)
Muscle Types:
•Skeletal Muscle
Skeletal muscles are predominantly used for movement. They are also known as
‘voluntary muscles’ as they are under our conscious control. Skeletal muscles are given
their names as they are connected to bones and the skeletal system. An example of a
skeletal muscle is the bicep. The skeletal muscles contract to create movement required in
everyday life.
•Smooth Muscle
Smooth muscle can be found in, for example, blood vessels and the digestive system. They
are used in the internal organs of the body. Smooth muscle is not controlled unconsciously
and therefore is also known as ‘involuntary muscles’. A example function of smooth muscle
is when the walls of the intestines contract to force food through.
•Cardiac Muscle
Cardiac muscle is only found in the heart and is the main part of the heart walls. This type
of muscle is also involuntary. Unusually, the cardiac muscle is the only muscle which does
not fatigue. The cardiac muscle contracts and relaxes to fill the heart with blood, to then
pass blood around to the body to working muscles and organs.
E)
Muscle Fibres:
-Type 1: These fibres are known as the slow twitch fibres. They are red in colour due to the large
amounts of myoglobin and oxygen. These fibres are resistant to fatigue and can produce repeated
contractions by producing ATP through an aerobic metabolic cycle. Type 1 fibres are needed in
athletes such as marathon runners and they have a large amount of these fibres.
-Type 2a: These fibres are known as fast oxidative fibres; they are a mixture of both fast and slow
twitch. Type 2a fibres contain large numbers of mitochondria and myoglobin; this explains why
they are red in colour. These fibres produce fast and strong muscle contractions but they are
more likely to tire than type 1. These fibres are needed for athletes such as 400m runners as they
need strong contraction but are also need more muscular endurance than a sprinter.
-Type 2b: These are known as fast glycolytic fibres; they are white in colour due to low levels of
myoglobin and few mitochondria. They are used for anaerobic activities such as sprinting;
therefore they would be required for 100m sprinters. This type of muscle fibre produces the
fastest and strongest muscle contractions but fatigue the quickest.
F)
The table above shows the characteristics of the 3 muscle fibres; type1, type 2a and type 2b.
There are similarities and differences between the muscle fibres and the characteristics they have. Type
1 muscle fibres have a slow speed of contraction compared to the other two; but type 2b’s contraction
speed is quicker than type 2a. Type 2b is has the largest force of contraction whereas type 1 has the
slowest. Although type 2a has a large contraction force it is not higher than type 2b. The size of the
muscle fibres shows a contrast between type 1 and type 2 muscle fibres. Type 1 has smaller size of fibres
than type 2. The mitochondrial density is higher in type 1 than both the type 2 fibres; this allows it to get
more energy to the working muscles making type 1 fibre better for endurance events such as a triathlon.
Type 1 is also the fibre that is the most resistant to fatigue, helping with events involving aerobic
activities and endurance events. In contrast, the type 2b fibre is the least resistant to fatigue and tires
quickly. Type 2a muscle fibres is more resistant to fatiguing than type 2b but is less than type 1. The
highest aerobic capacity is found in the slow twitch fibres, this aids in aerobic events. The type 2a muscle
fibres has a medium aerobic capacity and the type 2b has the smallest aerobic capacity; this makes these
less useful to endurance activities. The anaerobic density is high in the fast twitch fibres; allowing them
to be powerful for short bursts of time. This makes them good for events such as the 100m sprint in
athletics. The type 2a has a medium anaerobic density making it good for events such as 400m in
athletics; this is due to the contractions being less powerful but fatiguing less quickly, when compared to
type 2b.
G) Muscular Movement
Muscles contract as a group because they are dependent on other muscles to allow them to do their
job. Muscles work together in an antagonistic muscle action. Whilst one muscle contracts (the
agonist) the other relaxes (the antagonist). These muscle pairs allow the limb to move through the
joint’s range of movement. For example the biceps contract and the triceps relaxes during the
upwards stage. There are 4 roles a muscle can play; an agonist, antagonist, synergist and fixator.
-The agonist is the prime mover which contracts to produce the wanted movement. They produce a
normal range of movement in a joint by contracting. The agonist is known as the prime mover as it is
largely responsible for generating movements. During the upwards stage of a bicep curl the bicep is
the agonist.
-The antagonist is the muscle which acts oppositely to the agonist and is responsible for returning
the limb to its position. Whilst the agonist contracts, the antagonist relaxes, allowing movement to
occur. During the upwards stage of a bicep curl the tricep is the antagonist.
-The synergist is the muscle which helps the agonist in producing the movement needed. The
brachialis and brachioradrialis are the synergists in a bicep curl.
-The fixator is the muscles that fix the joints and the body in position to enable the movement to
happen. The fixator muscle in a bicep curl is the trapezius.
Types of muscle contractions:
-Concentric contraction; This is where the muscle shortens and tenses. The origin and insertion of the
muscle move closer together and the muscle becomes fatter. A concentric contraction is produced when a
movement occurs against gravity. An example of this is the bicep during the upwards phase of a bicep
curl, as it shortens.
-Eccentric contraction; This is where the muscles lengthens due to the origin and insertion moving further
away from each other. This is seen in the downwards stage of a bicep curl when the tricep is contracting
and lengthens as it works to resist gravity.
-Isometric contraction; This is where the muscle contracts but no movement is produced because the
muscle stays the same length. Isometric contractions occur when the body is in a fixed position. A sporting
example is the plank as you are held in a fixed position but your muscles are contracting.
-Isokinetic contraction; This is similar to isotonic contractions because the muscle changes length during
the contraction. It differs from the isotonic contractions is that it produces movement at a constant
speed. This is seen in swimming, where the water provides a constant resistance to the movement.