Download Muscular System

Muscular System
Muscles in Humans
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There are approximately 650 muscles in the human
body, each performing a unique role.
Muscles are the driving force behind the
musculoskeletal systems, enabling us to sit, stand,
walk, talk and do anything else that requires
movement.
They also keep our heart beating and help us
breathe.
In order to function, they must be able to react to
stimuli, contract, extend and return to their normal
shape.
Muscular System
Muscles are responsible for all types
of body movement
 3 basic muscle types are found in the
body
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Skeletal muscle
 Cardiac muscle
 Smooth muscle
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Characteristics of Muscles
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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Nervous system to muscles
Within the nervous system, nerve
impulses travel from neuron to neuron
along complex nerve pathways. The
junction between the parts of two such
neurons is called a "synapse.“
 If a sufficient amount of the substance
(called "neurotransmitter") is released,
the membrane is stimulated, and a
nerve impulse is triggered
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Neuromuscular junction occurs when a nerve
cell contacts a muscle
Comparison of Types of
Muscle
Types of Muscle, cont.
Myofilaments
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Muscle cells are unique because of the
contractible protein fibers, called myofilaments,
within them.
the filaments of myofibrils constructed from
proteins are of two types, thick and thin.
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Thin filaments consist primarily of the protein actin.
Thick filaments consist primarily of the protein myosin.
Muscle contraction occurs because of the myosin
filaments pull on actin filaments
Skeletal Muscle
Characteristics
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Most attach to
bones by tendon
Cells are
multinucleate
Striated—have
visible binding
Voluntary
Cells surrounded &
bundled by
connective tissue
Smooth Muscle
Characteristics
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Has no striations
Spindle-shaped
cells
Single Nucleus
Involuntary—no
conscious control
Found mainly in the
walls of hollow
organs
Characteristics of Cardiac
Muscle
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Has striations
Usually has a single nucleus
Joined to another cardiac
muscle cell
Involuntary
Found only in the heart
Connects cytoplasm between
2 cells (Gap junction)
Gap junctions are responsible for electrochemical and metabolic
coupling. They allow Each heart muscle cell is coupled to its
neighbors electrically by tiny holes, producing depolarization of the
heart muscle
Skeletal Muscle
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Functions of Skeletal
Muscle
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Produce Movement
Maintain posture
Stabilize joints
Generate Heat
Sites of Muscle
Attachment
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Bones
Cartilage
Connective tissue
coverings
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Muscle Fibers blend into a
connective tissue
attachment
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Tendon—cordlike structure
Aponeurosis—sheet-like
structure
Properties of Muscle
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Irritability – ability to receive
and respond to a stimulus
Contractibility – ability to
shorten when an adequate
stimulus is received
Extensibility – ability to
lengthen when an
adequate stimulus is
received
Elasticity – ability to return
to normal shape
Anatomy of a Muscle Cell
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Each fiber is built up from smaller
strands called myofibrils, and each
myofibril contains interlaced
filaments of muscle proteins.
Naming Skeletal Muscles
Direction of
Muscle
Fibers
Location
Action
Skeletal
Muscle
Origin
&
Insertion
Size
Shape
Number
Of
Origins
Direction of Muscle Fibers
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Relative to the Midline
RECTUS = parallel to the
midline
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TRANSVERSE =
perpendicular to midline
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Rectus Abdominus
Transverse Abdominus
OBLIQUE = diagonal to
midline
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External Oblique
Location
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Structure near
which muscle is
found
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FRONTALIS =
near FRONTAL
bone
OCCIPITALIS =
near OCCIPITAL
bone
Size
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Relative Size of Muscle
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
Number of Origins
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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
Shape
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Relative Shape of
the Muscle
DELTOID =
triangular shape Δ
TRAPEZIUS =
trapezoid shape 
SERRATUS = sawtoothed ♒
RHOMBOIDEUS =
rhomboid shape 
TERES = round ○
Origin & Insertion
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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)
Action
NAME
FLEXOR
EXTENSOR
ACTION
EXAMPLE
Decrease angle at a joint
Flexor Carpi Radialis
Increase angle at a joint
Extensor Carpi Ulnaris
ABDUCTOR
Move bone away from
midline
Abductor Pollicis Longus
ADDUCTOR
LEVATOR
Move bone toward midline
Adductor Longus
Produce upward movement
Levator Scapulae
DEPRESSOR
Produce downward
movement
Depressor Labii Inferioris
SUPINATOR
Turn palm upward/anterior
Supinator
PRONATOR
Turn palm
downward/posterior
Pronator Teres
Types of Muscle--Actions
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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
Head & Neck Muscles
Head & Neck Muscles
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Frontalis: elevate
eyebrows 
Orbicularis Oculi: close
eyelid 
Zygomaticus: draw angle
of lip upward 
Buccinator: draws cheeks
against teeth
Orbicularis Oris: closes
mouth 
Platysma: draws lower lip
down & back 
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Cranial Aponeurosis:
connects frontalis to
occipitalis
Temporalis: elevates
mandible
Occipitalis: draws
scalp back
Masseter: elevates
mandible
Sternocleidomastoid:
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Flexes head
Draws head toward
shoulder
Muscles of Mastication
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Masseter: elevates
mandible
Temporalis:
elevates mandible
Medial pterygoid:
elevates mandible
Lateral pterygoid:
depresses
mandible
Key Muscles of Facial Expression
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Smiling Muscles
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Orbicularis Oculi
Nasalis
Levator Labii
Superioris
Levator Anguli
Superioris
Zygomaticus
Risorius
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Frowning Muscles
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Frontalis
Orbicularis Oris
Depressor Anguli
Oris
Depressor Labii
Inferioris
Mentalis
Platysma
Muscles of the Axial Skeleton
Muscles of the Axial Skeleton
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Intrinsic Muscles
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Erector Spinae:
maintain posture of
back/extension
• Spinalis
• Longissimus
• Iliocostalis
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Oblique Muscles:
rotation of the
vertebrae
Muscles of Quiet
Respiration
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Abdominal Muscles
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• Semispinalis
• Multifidus
• Rotatores
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Diaphragm
External Intercostals
Internal Intercostals—
deep breaths
External Obliques
Internal Obliques
Transverse
Abdominus
Rectus Abdominus
Quadratus Lumborum
Muscles of Scapular
Stabilization
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Trapezius:
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Retraction (M)
Elevation (S)
Depression (I)
Upward Rotation (S, M)
Rhomboid—retraction
Levator Scapular—Elevation
Pectoralis Major—Protraction
Serratus Anterior—Protraction
Anterior Muscles of Shoulder
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Deltoid
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Pectoralis Major
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Flexion (A, M)/Extension (P,
M)
Abduction (M)/Adduction (A)
Internal (A) /External Rotation
(P)
Adduction
Flexion
Extension
Internal Rotation
Biceps Brachii—Flexion
Posterior Muscles of Shoulder
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Teres Major
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Latissimus Dorsi
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Adduction
Extension
Internal Rotation
Adduction
Extension
Internal Rotation
Triceps Brachii
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Adduction
Extension
Rotator Cuff Muscles (SITS)
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Supraspinatus
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Abduction
Infraspinatus
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External Rotation
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Teres Minor
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External Rotation
Subscapularis
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Internal Rotation
Muscles of the
Elbow/Forearm
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Triceps Brachii—
Extension
Bicep Brachii—
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Brachialis—Flexion
Brachioradialis—
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Flexion
Supination
Flexion
Pronation
Pronator Teres
Pronator Quadratus
Supinator Longus
Muscles of the Wrist & Hand
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Flexor Carpi
Ulnaris
Flexor Carpi
Radialis
Flexor Digitorum
Extensor Carpi
Ulnaris
Extensor Carpi
Radialis
Extensor Digitorum
Anterior (Palmar) View
Posterior (Dorsal) View
Muscles Of Hip:
Anterior Muscles
Muscles of Hip:
Anterior Muscles
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Medial/Adductor
Muscles:
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Adductor Magnus
Adductor Longus
Adductor Brevis
Gracilis
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Anterior Muscles
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Iliopsoas—Flexion
Pectineus—
• Flexion
• Adduction
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Sartorius—
• Flexion
• Lateral Rotation
Muscles of Hip:
Gluteal Muscles
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** Gluteus Minimus is under the
Gluteus Medius
Gluteus Maximus—
Extension
Gluteus Medius—
Abduction
Gluteus Minimus—
Abduction
Tensor Fasciae
Latae—
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Flexion
Abduction
Muscles of Anterior Thigh
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“Quadriceps”
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Rectus Femoris—
• Hip flexion
• Knee extension
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Vastus Lateralis—
knee extension
Vastus Medialis—
knee extension
Vastus Intermedius—
knee extension
Sartorius—
• Hip & Knee Flexion
• Lateral Hip Rotation
**Vastus Intermedius is
beneath Rectus Femoris
Muscles of Posterior Thigh
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“Hamstrings”
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Responsible for
Knee Flexion & Hip
Extension
Semimembranosus
Semitendinosus
Biceps Femoris
Gastrocnemius
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Knee Flexion
Muscles of the Lower Leg
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Anterior Compartment
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Posterior Compartment
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Tibialis Anterior—Dorsiflexion &
inversion
Extensor Digitorum Longus
Fibularis Tertius—dorsiflexion &
eversion
Gastrocnemius—plantarflexion,
knee flexion
Soleus—plantarflexion
Lateral Compartment
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Fibularis Longus—plantarflexion
& eversion
Fibularis Brevis—plantarflexion &
eversion
Throwing Movement
Running & Kicking
Tendinitis
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Inflammation of tendons and of
tendon-muscle attachments
Many patients report stressful
situations in their life in
correlation with the beginnings
of pain which may contribute to
the symptoms. If the symptoms
of tendinitis last for several
months or longer it is probably
tendinitis.
Muscular Diseases
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Muscular Dystrophy
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Muscular Dystrophy (MD) is a group of genetic diseases that cause
the muscle fibers to become easily damaged.
There are over one dozen different types, but the most common
general symptoms are muscle weakness, lack of coordination and
loss of mobility.
The most severe type, Duchenne's muscular dystrophy, can cause
mental retardation and primarily affects young boys.
MD is diagnosed through genetic tests, muscle biopsies, blood tests
that measure for high levels of creatine kinase and ultrasounds.
There is no cure for MD but it can be treated to reduce the severity
with physical therapy, medication, surgery and special braces.
Muscular Diseases
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Compartment Syndrome
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Compartment syndrome occurs when too
much pressure builds up in and around the
muscles.
It can result from crushing injuries, extended
pressure on a blood vessel, swelling inside a
cast or complications from surgery.
Symptoms include severe pain, a feeling of
fullness or tightness in the muscle and a
tingling sensation.
Numbness indicates cellular death and it may
be difficult to restore full function once it
reaches that point. Surgery to relieve the
pressure is usually required.
Fibromyalgia
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is a medical disorder characterized by chronic
widespread pain and allodynia, a heightened and
painful response to pressure
Fibromyalgia is estimated to affect 2–4% of the
population, with a female to male incidence ratio of
approximately 9:1
Fibromyalgia is considered a controversial diagnosis,
due to lacking scientific consensus to its cause
Signs and symptoms:
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Muscle spanms, weakness, nerve pain, muscles twitching,
palpitations, bowel disturbances, sleep disturbances,
short/long term memory, impaired speed performace, inability
to multitask, anxiety, depression, RA, headaches, etc…
Mitochondrial Myopathies
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On biopsy, the muscle
tissue of patients with this
disease category usually
demonstrate 'ragged red'
muscle fibers.
These 'ragged red' fibers
contain mild accumulations
of glycogen and neutral
lipids, and may show an
increased reactivity for
succinate dehydrogenase
and a decreased activity for
cytochrome c oxidase.
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Examples of Mitochondrial myopathy
include:
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varying degrees of cognitive impairment
and dementia
lactic acidosis (breakdown food)
strokes
transient ischemic attacks
hearing loss
Dysmotility (digestive muscles don’t work)
weight loss
cardiac conduction defects