Muscles
Function of Muscle
1. Muscle tissue is responsible for all body movements.
This includes body motion as in walking (Skeletal
Muscle) but also organ movement (smooth muscle)
such as dilation of blood vessels or heart contraction
(Cardiac Muscle).
2. Muscles support the functions of most our systems
that keep us alive: ie – respiration, digestion, blood
circulation …
3. Heating of body, muscle contractions give off heat
and help maintain body temperature. Shivering
warms the body when muscles in the skin contract
reflexively due to cold.
Muscle Tissue
Skeletal, Cardiac and Smooth
Cardiac Muscle
• Found only in the heart. Able to contract
independently of the brain but requires
signals from the brain to beat in correct sinus
rhythm.
Anatomy of a Skeletal Muscle
Skeletal muscle attaches to bone and moves our skeleton
Skeletal muscle is called voluntary muscle as it requires a conscious
command from the brain in order to move
Smooth Muscle tissue is found in the organs and vessels of the body.
Smooth muscle is called an involuntary muscle because it requires no
conscious signal from the brain to do its function and movements.
How Many??
• There are over 600 different muscles in our
body. Some are very large for gross motor
movement (kicking a ball) and some very tiny
fine motor control (blinking).
Tendon vs Ligament
Tendon – attaches muscle to bone
Ligament – attaches bone to bone
Properties of Muscle Fibre
Conductivity – can transmit an electrical or neural
impulse
Contractibility – ability to shorten in length
Extensibility – able to extend and become longer over
time (flexibility training/stretching)
Elasticity – able to be stretched and return to normal
length
Irritability – ability to respond to a stimulus (nerve
impulse)
Muscle Fibers
• Muscle Fibers are about the diameter of a human hair, they
can contract about ½ their length and can lift about 1000
times their weight.
• Muscle Fibers are malleable. When stimulated by an
electrical impulse they contract but need to be pulled back by
another force to return to their original length.
Motor Unit
A motor unit consists of the nerve (neuron) and
all the fibers connected to it. When a neuron is
stimulated all of its fibers will contract
completely. This is called the All or None
Principal. The number of motor units stimulated
the stronger the muscle contraction and vice
versa.
Gross Motor Movements
Big muscles with small # of motor units but
each motor unit controls larger numbers of
muscle fibers
Fine Motor
• Small muscles with lots of motor units to control
them but each motor unit controls fewer numbers of
muscle fibers.
Eccentric, Concentric and Isometric
Contractions
Muscle Strength
• Muscles can adapt to use. Muscle fibres get
thicker and stronger if they are exercised
regularly over time.
Micro Tears, Overload, Rest and Recovery
Strength Training
• During weight resistance training we try to
overload a muscle. This means work it beyond its
normal strength
• Overloading results in micro tears in the muscle
fibers. Tiny lesions in the fibers open up.
• During rest and recovery over the next 24 hours
the tears heal and make the fiber a bit larger in
diameter and as a result stronger
• Over time repeated training will result in larger
fibers and bigger, stronger muscles.
Muscle Concepts
• Transient Hypertrophy – Muscle temporarily get larger during
exercise due to increased blood flow. This lasts only for 30 minutes
or so after exercise. Does not increase strength.
• Chronic Hypertrophy – Muscle fibers diameters get bigger as they
adapt to repeated exercise training. As fibers get larger the muscle
gets bigger and stronger over time.
• Muscle Atrophy - Muscle fiber diameters get smaller over time as a
result of lack of use or training. Results in loss of strength.
• Hyperplasia – An unproven theory that increases in strength due to
exercise actually result in muscle fibers splitting and increasing in
number to account for increased strength.
• Voluntary Muscle – muscles that we consciously control like leg
muscles for walking
• Involuntary Muscle – muscles that function without conscious
control like our organs – blood vessels, stomach, heart…
Transient Hypertrophy
the muscle increases size from increased blood
flow, temporary (30 min) and no strength gain
Chronic Hypertrophy – muscle gets
larger and stronger from training
Muscle Atrophy – muscle shrinks from
disuse
Voluntary and involuntary
muscle
• Voluntary like writing
• Involuntary like pupil
dilation
Naming Muscles
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Location:
Shape:
Action:
Direction of Fibres:
Attachment Points:
Number of Heads:
Tibialis Anterior muscle
Trapezius
Extensor Digitorum
Tranversus Abdominus
Sternocleidomastoid
Biceps, Triceps
Location:
Tibialis Anterior muscle
Shape:
Trapezius
Action:
Extensor Digitorum
Direction of Fibres: Tranversus Abdominus
Attachment Points: Sternocleidomastoid
Number of Heads: Biceps, Triceps
Muscle Pairs
Agonist and Antagonist
• Example – Muscles work in pairs to counteract each
other’s movement. Example: the bicep is called the
agonist (primary mover) and the tricep is the
antagonist (returns the arm to its original position.
Tendons, Origin and Insertion
• Tendons connect the muscle to bone.
• Origin is the connection we call an anchor, it does not move
during the contraction
• Insertion is the connection that moves a bone during the
contraction.
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Muscle Strain and Tears
Symptoms: Pain, Weakness &
Function
Muscle Strains/Tears
Treatment of muscle injury
Rest – it takes time for the muscle to repair
Ice – helps reduce the swelling and pain
Compression – helps hold muscle in line and
reduce the pain and swelling
Return to action when function is no longer
impaired.
Returning too soon may result in re injury