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Muscular System
Week 4 - Overview of Muscular
System
• The body has over 600 muscles.
• These muscles function to allow a large range
of movement, both consciously and
unconsciously.
• The body’s health relies on subconscious
movements, for example the diaphragm and
intercostal muscles for breathing.
Functions of the Muscular System
1. Body Movement
2. Adequate Posture
3. Essential Bodily Functions
Body Movement
• All muscles that we constantly control are
attached to our bones.
• The central nervous system sends a message
to the relevant muscle.
• The muscle then pulls the bones to produce
the desired movement.
Adequate Posture
• Muscles are continually in a state of ‘tone’
that affects their ability to help our body
maintain an upright posture when awake and
to function safely during sleep.
• People with poor muscle tone generally have
poor posture and resultant aches and pains
because gravity is defeating the muscles’
resistance.
• Muscles of the back influence muscle posture.
Essential Body Functions
• The involuntary muscles that we have no
control over are continuously functioning and
preserving our ongoing bodily needs whether
we are awake or not.
• The heart is a muscle over which we generally
have little control, and muscular effort also
controls our digestive and breathing demands.
Structure of Muscles
• The middle of each muscle is normally the
thickest part, this is known as the muscle belly.
• At the ends of each muscle is a tendon that
attaches the muscle to bone that it is to move.
• Muscles are made up of 2 types of proteins that
are able to contract and relax.
• Inside muscle is stored energy that can be used
when desired.
• Muscles also have a rich supply of nerves and
blood vessels, and like bones, they contain water
which adds to their weight.
Muscles of the Body
You will need to know:
- Deltoids
- Hamstrings
- Quadriceps
- Pectoralis Major
- Biceps
- Gluteals
- Abdominals
- Trapezius
- Triceps
- Gastrocnemius
- Latissimus Dorsi
Week 5 – Names and
Classifications of Muscles
• There are three different types of muscle in
the body.
• They are skeletal, smooth and cardiac muscle.
• Each type of muscles has a different role to
play within the body.
Skeletal Muscles
• These types of muscles are often called
striated muscles because of their appearance.
• Skeletal muscles have a microscopic striped
appearance.
• These muscles are voluntary muscles and
work to produce movement of the limbs etc.
Skeletal Muscle cont…
• Skeletal muscles create movement by pulling on the muscles
which they are attached to.
• Muscles can only pull not push, so they need to work in pairs to
produce movement.
• For example, when the bicep pulls up, the tricep needs to relax or
stretch to allow movement.
• Then, when the arm is pulled back down the bicep needs to relax
while the tricep contracts.
• The same process occurs when you kick a football, the quadriceps
pull and contract while the hamstring relax and lengthen.
Smooth Muscle
• Are found in the digestive system and the
walls of other vital organs such as the bladder
and blood vessels.
• These muscles are classed as involuntary as
we have no conscious control over their
movements.
• Smooth muscles help with the digestion of
food. For example the oesophagus contracting
to move food to the stomach.
Cardiac Muscle
• Is the muscle of the heart.
• It is also striated, like the skeletal muscle, but
is involuntary, like smooth muscle.
• This is an effective combination for its
demanding role for a persons health and
wellbeing.
Connective Tissue…in detail
• Has an important role in both the skeletal and
muscular system.
• It is classed as soft tissue as it does not have
the rigidity that bone has and it does have the
flexibility of soft tissue, as well as all the
strength that collagen provides.
Cartilage
• This smooth, elastic tissue is found in different
forms in the body.
• Hyaline cartilage coats the ends of bones in
synovial joints.
• Discs of cartilage separate the vertebrae in the
spine.
• Ribs attach to the sternum via cartilage.
• The hard part of the ear, and your nose are
also cartilage.
Tendons
• As we already know, connect muscle to bone.
• They are inelastic and very strong to allow movement by
muscles pulling through the joint and on the bones.
• The biceps muscle is an example of a muscle that works
through two joints
• It has two tendonous origins at the scapular (allowing the
humerus to flex away from the body) and the tendonous
insertion into the radius in the forearm allows the forearm to
flex upwards towards the humerus.
Muscle Fibres
• There are two muscle fibre types within the
muscular system.
• These are called slow twitch fibres (red) and
fast twitch fibres (white).
• Each is better suited to a different intensity of
physical activity.
Fibre Types
Week 6
Skeleton and Muscle Quiz
http://videos.howstuffworks.com/hsw/
11527-the-skeletal-and-muscularsystems-video-quiz-video.htm
Week 7 - Muscular Contractions
• There are three types of muscular
contractions:
– Isotonic
– Isokinetic and;
– Isometric
Isotonic Contractions
• These contractions change the length of the
muscle when creating a force.
• Muscle shortening = concentric contraction
• Muscle lengthening = eccentric contraction
Isokinetic Contractions
• These contractions allow the performer to work at a
constant velocity against a weight or resistance that
changes as the performer moves through the
working muscles possible range of movement.
• These contractions are only possible with specialised
equipment.
• Muscles are stronger or weaker depending on the
degree of flexion around the joint.
• Isokinetic equipment is able to accommodate these
differences and allow the muscle to work maximally
at all degrees of flexion throughout the training
movement
Isometric Contractions
• This contraction creates force but there is no
change in the muscle length.
• This contraction produces the most amount of
force for any contraction type and as such the
muscle tires quickly.
• Eg, rugby scrum, balance in gymnastics.
Origin and Insertion to Create
Movement
• The origin is the attachment that is closer
(proximal) to the body.
• The insertion is further away (distal) from the
midline of the body.
• The insertion is usually attached to the bone
that moves the most when the muscle
contracts.
Week 8 – Nervous Control of
Muscles
• To enable the muscles to move, the brain must send electrical
nervous messages to the muscle.
• These message travel through the spinal cord to the motor
nerves which branch from the spinal cord to the appropriate
muscle.
• Leaving the spinal cord, the nerve splits into motor neurons
which then divide a number of times to attach to individual
muscle fibres.
• When the neurons meets the muscle fibres there is a gap
(called the neuromuscular junction or synaptic cleft) across
which the nerve impulse has to jump.
Neurotransmitter
• Acetylcholine is the name of the
neurotransmitter that helps the nerve impulse
make that jump.
• The muscle will continue to contract for as
long as the brain continues to send it
messages and the relevant energy sources
lasts.
Motor unit
• One motor neuron and the fibres that it controls is called a
motor unit.
• When an electrical impulse tells the fibres to contract, all the
fibres linked to this nerve contract totally.
• This is called the all or none principle.
• This does not mean that all of the fibres within one muscle
are always contracted, just the ones connected to that
particular motor neuron.
• For example, fewer motor neurons would be stimulated for
picking up a can then to perform a bicep curl.
The Process of Muscular
Contraction