Download Muscular System

Muscular System
Muscles: Designed for Motion
How Muscles are Classified
• Muscles – The three main types of
muscles are skeletal, smooth, and cardiac
– Voluntary Muscles – Muscles that are
generally under conscious control (usually
skeletal)
– Involuntary Muscles – Muscles that not under
conscious control (smooth and cardiac)
• Skeletal Muscles – Primary function is to move
the skeleton, made of muscle fibers
– Muscle Fibers (Cells) – Bound together in
parallel bunches, the contracting mechanism
causes the muscle to be striated or striped.
– Striated Muscle – Another name for skeletal
muscle
• Smooth Muscle – Shorter, wider cells in a looser
arrangement, specialized for long, slow,
powerful contractions, used in circulatory and
digestive systems, in the iris, and in women
during birth
• Cardiac Muscles – Similar to skeletal
muscle but designed to contract
continually, only found in the heart and is
self stimulating
Important Muscles
• Sternocleidomastoid
– Connect the
temporal bones to
the sternum and
clavicle, Allows for
movement of the
head
• Temporalis – Moves
the lower jaw when it
is chewing or talking
• Masseter – Located
near your lower jaw
and works with the
Temporalis
• Trapezius –
Connected to the
spine, head, and
scapula, moves
shoulders back and
up, raises the head
• Intercostal Muscles –
Muscles between the
ribs, used to raise the
rib cage and expand
the thoracic cavity
when they contract
• Pectoralis Major –
Connected to the
sternum, extends
across the chest and
connects to the
humerus, used when
you push your hands
in front of your body
• Deltoid – Connected to
your clavicle and
humerus (shoulder),
used in raising your
arm away from your
body
• Latissimus Dorsi –
Connects each
humerus to the
lumbar region, used
for drawing your arms
toward your body
• Biceps Brachii – Located on the front of each
upper arm, used to bend your forearm toward your
body
• Triceps Brachii – Located on the back of each
upper arm, used to straighten the arm
• Fingers
Flexed/Extended –
Muscles in the
forearm connected to
tendons that run to
the hands allow the
fingers to be flexed
and extended
• Rectus Abdominus –
(6-pack Abs) Extend
from the bottom of the
sternum to the top of
the pelvic girdle, used
when you sit up from
reclining
• External Oblique –
Connect the ribs to the
pelvis, used for
bending sideways
(Laterally)
• Erector Spinae – Extend
vertically along the spine
from the upper back to the
pelvis, used to hold your
body upright
• Gluteus Maximus – (butt)
Largest and strongest
muscle in the whole body,
connected to pelvis and
femur, used to move the
leg downward and to the
rear
• Quadriceps Femoris –
A group of four
muscles on the front
of the upper leg, used
to straighten the leg
• Sartorius – Connects
the outside of the
pelvic bone to the
inside of the tibia,
used to lift the lower
leg and turn it inward
• Hamstrings – A group
of three muscles on
the back of the upper
leg, used to bend the
leg at the knee
• Gastrocnemius –
Largest muscle on the
back of the lower leg,
used to extend the
foot downward
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Engineered for Power
The Design of Skeletal
Muscle
• Fascia (8)
(Epimysium) – The
tough translucent
sheath that covers the
entire muscle
• The fascia tapers at
each end into tendons
(7) that connect the
muscle to the bone
• Fascicle (9) – Inside the muscle there are
bundles of muscle cells called fascicles
• Perimysium (1) – The outer covering of a fascicle
made of connective tissue
• Nerves and vessels (2) run between the fascicles
to supply food and oxygen and signal the muscle
to contract
• Muscle Fiber (Cell)
(4) – Inside the
fascicle there are
many muscle fibers
that are made of
many microfibrils
– Each muscle is made
of millions of muscle
fibers (cells)
– Each muscle cell has
many nuclei and an
unusually large
amount of
mitochondria
• Microfibril (6) – Long tubes bunched
together to make each muscle fiber; they
are made of many sarcomeres
• Endomysium (3) – Tough connective
tissue between the muscle fibers
• Sarcolemma (Cell Membrane) (5) - The
outer covering of the muscle fiber (cell)
• Sarcomere (12) – Overlapping protein fibers
made of thick (myosin) and thin (actin) filaments
that work together to contract the muscle (this is
why skeletal muscles have a striated
appearance)
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Muscle contraction
• Neuromuscular
Junction – Where the
nerve connects to the
muscle, triggers the
muscle to contract
• On average one nerve
can stimulate 100
muscle cells
• The group of muscle cells stimulated by a nerve
cell is called a motor unit
• A motor unit allows there to be less nerve cells for
every muscle cell
• If there are less muscle cells per nerve
cell, those muscles are more precise
• If there are more muscle cells per nerve
cell, those muscles are less precise
• Each muscle has thousands of motor
units, when you use a muscle some of the
units contract while others are relaxed
• All-or-none Principle – When motor units
are stimulated, they completely contract
and completely relax until stimulated again
Muscles in Strength and Weakness
Exercise is Healthy for Muscles
• Hypertrophy – The enlargement of muscles
through use
• Atrophy – The
degeneration of
muscles through
the lack of use
• Red Fibers – Muscle fibers that contain a large
amount of mitochondria and myoglobin; have
a pronounced red color
– Contract more slowly, but have more endurance, are
called slow-twitch fibers
– Myoglobin – A protein that stores oxygen
• White Fibers – Muscle fibers that
contain smaller amounts of
mitochondria and myoglobin; do not
have a pronounced red color
– Have more myofibrils and contract faster
and more strongly, are called fast-twitch
fibers
• You can train your muscles to perform a
certain task
• A weightlifter and marathon runner have
about the same amount of muscle cells,
they are just trained for a different task.
• Weight Lifter
Has more White
Fibers
• Marathon Runner
Has more Red
Fibers
Exercise
• We need to continue to exercise so the muscle
will at least remain in the same condition
• If we do not exercise our muscles will
deteriorate
• Warming up –
Allows muscle
contraction and
cellular respiration
to occur more
efficiently
• Cooling down –
Allows excess lactic
acid to be removed
from the muscle to
reduce soreness
• If a muscle is strained,
there is usually no
noticeable strength loss
after healing
• Muscle Fatigue – When
a muscle becomes stiff,
sore, and difficult to
contract
– Caused by a build-up of
waste products in the
muscle
• Cramp – A sudden ,
painful, involuntary
contraction, caused by a
lack of ATP
• Muscle Tone – A state of slight tension
in a relaxed muscle, which a small
number of cells are contracted
– Allows your muscles to be ready for action
– Needed for good posture
• A Functioning Unit
• Both skeletal and muscular systems need all
the other systems to be working together with
them.
• Skeletal system gives the muscular system a
support
• Nervous system sends electrochemical signals
to the muscular system to contract
• Muscle Sense – Sensors in the muscle
tissue relay messages to the brain,
informing it of location and tension