Download The Muscular System

Muscular System
Mrs. Yanac
Anatomy & Physiology
Big Ideas
Muscle makes us over ½ of the body’s mass
 Consists of over 600 muscles
 Consumes a large amount of energy
obtained through diet
 Muscles can ONLY contract & shorten in
length
 Categorized into 3 categories

– Skeletal, Cardiac, Smooth
Muscle Types

All body movements are determined by three
types of muscles
– Smooth (Involuntary)
 cannot be controlled by will
– Cardiac (Involuntary)
 control the contractions of the heart
– Skeletal (Voluntary)
 can be controlled by will
Functions of Skeletal Muscle

Provides voluntary
movement of body
– Enables breathing,
blinking, and smiling
– Allows you to hop, skip,
jump, or do push-ups
Maintains posture
 Produces heat

Function of Smooth Muscle

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Called smooth muscle because they are
unmarked by striations, small spindle shaped
Unattached to bones, act slowly, do not tire
easily and can remain contracted for a long
time
Not under conscious control so they are also
called involuntary muscles
Found in walls of internal organs (intestines,
bladder, stomach, uterus, blood vessels)

Provides movement of
internal organs
– Moves food through
digestive tract (peristalsis)
– Enables bladder control

Causes involuntary actions
– Reflex actions
– Adjusts opening of pupils
– Causes hair to stand on
end
Function of Cardiac Muscle
Found only in the heart
 Involuntary muscle
 Requires a continuous supply of
oxygen to function
 Cardiac muscle cells begin to die
after 30 seconds of oxygen cutoff
 Striated and branched
 Directs circulation of blood

Special muscles

Sphincter (dilator) muscles are openings
between
– the esophagus and stomach
– the stomach and small intestines
– walls of the anus, urethra and mouth

Open and close to control passage of
substances
Characteristics of Muscles

All muscles have 4 common characteristics
– Excitability – ability to respond to a stimulus
(ie: nerve impulse)
– Contractibility – muscle fibers that are
stimulated by nerves contract (become
shorter) and causes movement
– Extensibility – ability to be stretched
– Elasticity – allows the muscle to return to its
original shape after it has been stretched
Sources of Heat/Energy
When muscles work, they produce heat
that our body needs to function properly
 Major source of this energy is ATP – a
compound found in muscle cells
 ATP requires muscle cells to have oxygen,
glucose and other materials circulated by
the blood
 When the muscle is stimulated, ATP is
released, thus producing heat

Muscle Contraction

Sliding Filament Theory
Attachments & Actions of
Skeletal Muscles


Actions depend largely
on what the muscles are
attached to
Attachment sites
– Origin – an attachment
site for a less movable
bone
– Insertion – an
attachment site for a
more moveable bone
Attachments & Actions

(cont.)
Movement usually produced by a group of
muscles
– Prime mover – muscle responsible for most
of the movement
– Synergists – muscles that help the prime
mover by stabilizing joints
– Antagonist (agonist) – produces movement
opposite to prime mover
 Relaxes when prime mover contracts
Attachments & Actions:
Body Movements
Flexion – bending a body
part
Extension –
straightening a body
part
Hyperextension –
extending a body part
past the normal
anatomical position
Dorsiflexion – pointing
the toes up
Plantar flexion –
pointing the toes down
Abduction – moving a
body part away from the
anatomical position
Adduction – moving a
body part toward the
anatomical position
Attachments & Actions:
Body Movements (cont.)
Circumduction – moving a
Inversion – turning the
body part in a circle
sole of the foot medially
Pronation – turning the
Eversion – turning the sole
palm of the hand down
Supination – turning the
palm of the hand up
of the foot laterally
Retraction – moving a
body part posteriorly
Protraction – moving a
body part anteriorly
Attachments & Actions:
Body Movements (cont.)
Elevation – lifting a body
part; for example,
elevating the shoulders
as in a shrugging
expression
Depression – lowering a
body part; for example,
lowering the shoulders
Let’s watch Hank give his
overview
Crash Course – Big Guns
https://www.youtube.com/watch?v=jqy0i1K
XUO4
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Major Skeletal Muscles

The muscle name
indicates
–
–
–
–
Location
Size
Action
Shape
OR
– Number of
attachments of the
muscle

As you study muscles,
you will find it easier
to remember them if
you think about what
the name describes.
MUSCLES YOU SHOULD KNOW
THE FUNCTIONS OF:
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Biceps – flexes lower arm
Deltoid – abducts arm; injection site
Sternocleidomastoid – turns head
Gastrocnemius – flexes sole of feet
Latissimus dorsi – extends & adducts upper arm
Pectoralis major – adducts and flexes upper arm
Intercostals – moves ribs for breathing
Trapezius – extends head, moves shoulder
 Triceps – extends lower arm
 Gluteus maximus – extends thigh;
injection site
 Sartorius – abducts thigh, flexes leg
 Vastus lateralis – extends leg
 Rectus abdominus – compresses the
abdomen
 Rectus femoris – flexes thigh & extends
lower leg
 Tibialis anterior – flexes and inverts foot

Muscle Strains and Sprains

Strains – injuries due to over-stretched
muscles or tendons
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Sprains – more serious injuries that result in
tears to tendons, ligaments, and/or cartilage of
joints
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RICE is recommended treatment for either
–
–
–
–
Rest
Ice
Compression
Elevation
Muscle Strains and Sprains

(cont.)
Prevention
– Warm up muscles

A few minutes before an intense activity raises
muscle temperature and makes muscle more
pliable
– Stretching

Improves muscle performance and should always
be done after the warm-up or after exercising
– Cooling down or slowing down

Before completely stopping prevents pooling of
blood in the legs and helps remove lactic acid
from muscles
Aging and the Musculoskeletal System

Contractions become slower and not as
strong
– Dexterity and gripping ability decrease
– Mobility may decrease
Assistive devices helpful
 Routine exercise

– Swimming
– Physical therapy
Diseases and Disorders of the Muscular
System
Disease
Botulism
Description
Affects the gastrointestinal tract and various
muscle groups
Fibromyalgia
Fairly common condition that causes chronic
pain primarily in joints, muscles, and tendons
Muscular
Inherited disorder characterized by muscle
Dystrophy
weakness and a loss of muscle tissue
Myasthenia gravis Autoimmune condition in which patients
experience muscle weakness
Diseases and Disorders of the Muscular
System (cont.)
Disease
Description
Tennis/Golfer’s
elbow
Tendonitis
Tendon damage in the area of the elbow from
repeated use of forearm
Painful inflammation of a tendon and the
tendon-muscle attachment to a bone
Carpal Tunnel
Syndrome
Compression in nerves in the wrist leads to
tingling and pain in the hand, wrist, & forearm
Fibromyalgia
Chronic, widespread pain in specific muscle
site; numbness and tingling in arms or legs;
headaches. Cause unknown.
Problems from lack of movement
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Contractures
– Tightening and shortening of a muscle resulting in a
permanent flexing of a joint

Muscle atrophy
– Muscles become weak and joints become stiff
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Circulatory impairment
– Blood clots and pressure ulcers can develop

Mineral loss
– Especially calcium from the bones making bones
brittle and easily to be fractured

Other problems
– Poor appetite; constipation; urinary infections;
respiratory problems; and pneumonia
Everyone has a 'risk muscle.' You
keep it in shape by trying new
things. If you don't, it atrophies.
Make a point of using it at least
once a day.
~Roger von Oech
Check out this link to learn more

Interactive Body