Download Skeletal Muscles

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Approximately 40% of your body weight
Approximately 650 muscles
Muscles only pull (they can’t push)
You have over 30 facial muscles
Eye muscles move more than 100,000 times a
day
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Skeletal
Cardiac
Smooth
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Definition - organs that are composed
mainly of skeletal muscle tissue, but they
also contain connective tissues, nerves,
and blood vessels.
Each cell is a single muscle fiber.
Muscle fibers form bundles called
fascicles.
Directly or indirectly attached to the
bones of the skeleton
Muscle plays six important roles in the body:
1. Produce skeletal movement
2. Maintains posture and body position
3. Support soft tissues (abdominal wall & pelvic
cavity)
4. Guard entrances and exits (digestive and urinary
tracts)
5. Maintain body temperature (energy is converted
to heat)
6. Store nutrient reserves (proteins are broken
down & amino acids are used)
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The muscle fibers in a single fascicle are parallel, but
the organization of fascicles in skeletal muscles can
vary
The arrangement is correlated with muscle power and
range of motion (structure determines function)
Skeletal muscles are classified as:
Parallel muscles (most common) – fascicles are parallel
to the long axis of the muscle
Convergent muscles – converge at a common
attachment site; fibers spread out and pull in different
directions
Pennate muscles – form a common angle with the
tendon
Circular muscles – cocentrically arranged around an
opening
Three layers of connective tissue are part of each
muscle:
1.
Epimysium – dense layer of collagen fibers that
surround the entire muscle
2.
Perimysium – divides the muscle into a series of
compartments each containing a bundle of muscle
fibers (fascicle); contains collagen & elastic fibers,
blood vessels and nerves that maintain blood flow
3.
Endomysium – flexible, elastic connective tissue
layer; surrounds the individual skeletal muscle
cells and interconnects adjacent muscle fibers
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At the end of the muscle, the collagen fibers of
the epimysium, perimysium, and endomysium
come together to form a tendon or aponeurosis
Tendons and aponeuroses attach muscles to
bone
Origin – where the fixed end of the muscle
attaches to the bone (cartilage or connective
tissue)
Insertion – where the movable end of the
muscle attaches to another structure
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Gastrocnemius – calf
muscle that extends from
the distal portion of the
femur to the calcaneus
When it contracts it pulls
the calcaneus toward the
knee
Origin – femur
Insertion - calcaneus
Naming of Skeletal Muscles
 Direction of muscle fibers
Example: rectus (straight)
 Relative size of the muscle
Example: maximus (largest)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Naming of Skeletal Muscles
 Location of the muscle
Example: many muscles are named
for bones (e.g., temporalis)
 Number of origins
Example: triceps (three heads)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Naming of Skeletal Muscles
 Location of the muscles origin and insertion
 Example: sterno (on the sternum)
 Shape of the muscle
 Example: deltoid (triangular)
 Action of the muscle
 Example: flexor and extensor
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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Axial muscles arise on the axial skeleton (60%
of skeletal muscles) ; position the head and
spinal column and move the rib cage
Appendicular muscles stabilize and move the
appendicular skeleton (40% of skeletal
muscles)
Head and Neck Muscles
Figure 6.14
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Trunk Muscles
Figure 6.15
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Deep Trunk and Arm Muscles
Figure 6.16
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Muscles of the Pelvis, Hip, and Thigh
Figure 6.18c
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Muscles of the Lower Leg
Figure 6.19
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Superficial Muscles: Anterior
Figure 6.20
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Superficial Muscles: Posterior
Figure 6.21
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Agonist (prime mover) – a muscle whose
contraction is mostly responsible for producing a
particular movement
Example – biceps brachii
 Antagonist – a muscle whose action opposes that
of a particular agonist
Example – triceps brachii
 Agonists and antagonists are functional opposites
 Synergists – help a larger agonist work efficiently
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Muscle Tone – resting tension in a
skeletal muscle
Isotonic muscle contraction – tension
rises and the skeletal muscle’s length
changes (lifting)
Isometric muscle contraction – the
muscle as a whole does not change
length, and the tension produced never
exceeds the load (holding)
Types of Ordinary Body
Movements
 Flexion – bending at the joint
 Extension - straightening at the joint
 Hyperextension
 Rotation – rotating on axis
 Abduction – moving away from the
midline
 Adduction – moving toward the body
 Circumduction – circular movement
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Body Movements
Figure 6.13
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Special Movements
 Dorsifelxion
 Plantar flexion
Special Movements
 Inversion
 Eversion
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Opposition
 Supination
 Pronation
Strain vs. Sprain
What is a strain?
Strains are injuries that involve the stretching
or tearing of a musculo-tendinous (muscle and
tendon) structure
What is a sprain?
A sprain is an injury involving the stretching or
tearing of a ligament (tissue that connects bone
to bone)
Ankle Sprains
Examples of Strains
Grade I (mild) sprain or strain involves
some stretching or minor tearing of a
ligament or muscle.
Grade II (moderate) sprain or strain is a
ligament or muscle that is partially torn
but still intact.
Grade III (severe) sprain or strain means
that the ligament or muscle is completely
torn, resulting in joint instability.
R
– rest
I - immobilize (ice)
C - compression
E - elevation
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Most surgery for ACL injuries involves
replacing the ACL with tissue called a graft
Usually an autograft (tendon taken from
another part of the body) is used
The most common grafts used are the tendon
of the kneecap or one of the hamstring tendons
Another choice is allograft tissue, which is
taken from a deceased donor
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Repairs an injured elbow ligament (UCL
construction)
A surgeon replaces the injured UCL with a
tendon taken from somewhere else in the
patient’s body
Duchenne Muscular Dystrophy (DMD)
Definition - One of nine types of muscular dystrophy, a group of
genetic, degenerative diseases primarily affecting voluntary muscles.
Cause - An absence of dystrophin, a protein that helps keep muscle cells
intact.
Information obtained from: http://www.mda.org/disease/dmd.html
Onset - Early childhood - about 2 to 6 years.
Symptoms - Generalized weakness first affecting the
muscles of the hips, pelvic area, thighs and shoulders.
Calves are often enlarged.
Progression - DMD eventually affects all voluntary
muscles, and the heart and breathing muscles.
Inheritance - X-linked recessive. DMD primarily affects
boys, who inherit the disease through their mothers.
Women can be carriers of DMD but usually exhibit no
symptoms.
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