Transcript THE MUSCULAR SYSTEM

Dr Idara
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Muscles are responsible for all types of body
movement
3 basic muscle types are found in the body.
They are:
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Skeletal muscle
Cardiac muscle
Smooth muscle
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Muscle cells are elongated
(muscle cell = muscle fiber)
Contraction of muscles is due to the
movement of microfilaments
All muscles share some terminology
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Prefix myo refers to muscle
Prefix mys refers to muscle
Prefix sarco refers to flesh
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Scaterred throughout the sarcoplasm is the
sarcoplasmic reticulum
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The sarcoplasm contains myoglobin
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It stores Calcium ions
Red pigmented protein related to Hemoglobin
that carries oxygen
Along entire length are myofibrils
Myofibrils made of protein filaments
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Come in thick and thin filaments
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Most attach to bones
by tendon
Cells are multinucleate
Striated—have visible
binding
Voluntary
Cells surrounded &
bundled by connective
tissue
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Picture sub A
Has no striations
Spindle-shaped cells
Single Nucleus
Involuntary—no
conscious control
Found mainly in the
walls of hollow organs
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Picture sub B
Has striations
Usually has a single
nucleus
Joined to another
cardiac muscle cell
Involuntary
Found only in the heart
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Functions of Skeletal
Muscle
 Produce Movement
 Maintain posture
 Stabilize joints
 Generate Heat
Sites of Muscle
Attachment
 Bones
 Cartilage
 Connective tissue
coverings
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Muscle Fibers blend into a
connective tissue attachment
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Tendon—cordlike structure
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Aponeurosis—sheet-like
structure
Properties of Muscle
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Irritability – ability to receive
and respond to a stimulus
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Contractibility – ability to
shorten when an adequate
stimulus is received
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Extensibility – ability to
lengthen when an adequate
stimulus is received
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Elasticity – ability to return to
normal shape
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A muscle cell is also called a muscle Fiber
A discrete bundle of muscle cells is called a
Fascicle
The thin connective tissue that surrounds
each muscle cell is called Endomysium
The connective tissue that surrounds each
Fascicle is called Perimysium
The connective tissue surrounding the entire
muscle is called Epimysium
Direction of
Muscle
Fibers
Location
Action
Skeletal
Muscle
Origin
&
Insertion
Size
Shape
Number
Of
Origins
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Structure near which
muscle is found
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FRONTALIS = near
FRONTAL bone
OCCIPITALIS = near
OCCIPITAL bone
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Relative Size of Muscle and
location
MAXIMUS = largest
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MEDIUS = middle
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Fibularis Longus
BREVIS = short
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Gluteus Minimus
LONGUS = longest
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Gluteus Medius
MINIMUS = smallest
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Gluteus Maximus
Fibularis Brevis
TERTIUS = shortest
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Fibularis Tertius
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Number of tendons of
origin
BICEPS = Two
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TRICEPS = Three
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Biceps Brachii
Biceps Femoris
Triceps Brachii
QUADRICEPS = Four
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Quadriceps Femoris
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Relative Shape of the
Muscle
DELTOID = triangular
shape Δ
TRAPEZIUS = trapezoid
shape 
SERRATUS = sawtoothed ♒
RHOMBOIDEUS =
rhomboid shape 
TERES = round ○
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Origin – attachment to
an immoveable bone
Insertion – attachment
to a movable bone
ILIO COSTALIS=
attaches to the ilium &
ribs (costal = ribs)
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Prime mover (Agonist) – muscle with the
major responsibility for a certain movement
Antagonist – muscle that opposes or
reverses a prime mover
Synergist – muscle that aids a prime mover
in a movement and helps prevent rotation
Fixator – stabilizes the origin of a prime
mover
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Smiling Muscles
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Orbicularis Oculi
Nasalis
Levator Labii Superioris
Levator Anguli oris
Zygomaticus
Risorius
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Frowning Muscles
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Frontalis
Orbicularis Oris
Depressor Anguli Oris
Depressor Labii
Inferioris
Mentalis
Platysma
Frontalis - Used in frowning
Orbicularis Oculi –
Surrounds the eye, eyelid
and orbit. Used to close
the eyes
Zygomaticus - Used in
smiling
Buccinator- A flat muscle of
the cheek, draws in
the cheek and puffs up the
cheeks. Called the
Trumpeter’s Muscle.
Orbicularis Oris- surrounds
the mouth, closes the
lips when contracted and
used for whistling and
kissing.
Masseter- Is the Prime
mover for jaw closure.
Also used for chewing.
Temporalis - is the
synergist for jaw closure
and assists with
chewing.
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Intrinsic Muscles
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Erector Spinae: maintain
posture of back/extension
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Spinalis
Longissimus
Iliocostalis
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Semispinalis
Multifidus
Rotatores
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Diaphragm
External Intercostals
Internal Intercostals—deep
breaths
Abdominal Muscles
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Oblique Muscles: rotation of
the vertebrae
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Muscles of Quiet Respiration
External Obliques
Internal Obliques
Transverse Abdominus
Rectus Abdominus
Quadratus Lumborum – Fixes
the lower rib during
respiration and cause lateral
flexion of the vertebral
column.
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Cerebral Palsy: This disorder is
characterized by paralysis and or weakened
muscles due to loss of muscle tone.
It can be caused due to lack of oxygen to the
region of the motor region of the cerebrum
of the brain which controls conscious control
of muscles.
This is often attributed to complication
during birth.
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Myalgia: Muscle pain due to strain, tearing of
muscle fibers. It also is a symptom of an
immune response along with a fever.
Myositis: Inflammation of muscle tissue due to
injury or disease.
Charley Horse (fibromyositis): Inflamation of
muscle tissue and the tendons associated with
that muscle due to injury (tear or severe
bruising- contusion).
Cramps: Painful, involuntary muscle
contraction, typically caused by fatigue or
strain.
A Series of genetic disorders characterized by
the atrophy or wasting away of skeletal
muscle.
 Duchenne Muscular Dystrophy is the most
common and affects primarily males.
X- linked recessive mutation i.e. mother’s
transmit disease to their sons.
Onset before 5 years of age.
Deletion of the dystrophin gene
Onset in adolesence or early adulthood.
Mutated dystrophin gene