Download introduction to myology

Introduction to Myology: gross and
microscopic features
Dr hemed El-busaidy
objectives
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Muscle Function
Muscle Characteristics
Muscle Tissue Types
Functional classification of muscle
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Muscle Function
Movement
Respiration (diaphragm, intercostals)
Communication (verbal/facial)
Thermogenesis
Heart beat
Constriction of organs/vessels
• Protection eg abdominal viscera
• Posture Maintenance
• Joint Stabilization
• Stronger muscles = greater protection,
increased joint stability
Properties of Muscle
• Excitability: capacity of muscle to respond
to a stimulus
• Contractility: ability of a muscle to shorten
and generate pulling force
• Extensibility: muscle can be stretched back
to its original length
• Elasticity: ability of muscle to recoil to
original resting length after stretched
Types of Muscle
• Skeletal
– Attached to bones
– Makes up 40% of body weight
– Responsible for locomotion, facial expressions, posture, respiratory
movements, other types of body movement
– Voluntary in action; controlled by somatic motor neurons
• Smooth
– In the walls of hollow organs, blood vessels, eye, glands, uterus, skin
– Some functions: propel urine, mix food in digestive tract, dilating/constricting
pupils, regulating blood flow,
– In some locations, autorhythmic
– Controlled involuntarily by endocrine and autonomic nervous systems
• Cardiac
– Heart: major source of movement of blood
– Autorhythmic
– Controlled involuntarily by endocrine and autonomic nervous systems
Muscle Tissue Types
Cardiac Muscle
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Branching cells
One/two nuclei per cell
Striated
Involuntary
Medium speed contractions
Smooth Muscle
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Fusiform cells
One nucleus per cell
Nonstriated
Involuntary
Slow, wave-like
contractions
Skeletal Muscle
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Long cylindrical cells
Many nuclei per cell
Striated
Voluntary
Rapid contractions
Muscle types based on fiber
orientation
Muscles and Body Movements
 Muscles are
attached to at
least two points
 Origin –
attachment to an
immoveable bone
 Insertion –
attachment to a
movable bone
Figure 6.12
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
Types of Ordinary Body
Movements
 Flexion – decreases angle of joint and
brings two bones closer together
 Extension- opposite of flexion
 Rotation- movement of a bone in
longitudinal axis, shaking head “no”
 Abduction/Adduction (see slides)
 Circumduction (see slides)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.32
Body Movements
Figure 6.13
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.33
More Types of Movement……
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Inversion- turn sole of foot medially
Eversion- turn sole of foot laterally
Pronation- palm facing down
Supination- palm facing up
Opposition- thumb touches tips of fingers on
the same hand
Types of Muscles
 Prime mover – 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
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.35
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
Slide
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
Slide
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 (flexes or
extends a bone)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.37
Muscles of the head (face)
Muscles of the neck
Muscles of the trunk (anterior)
Muscles of the trunk (posterior)
Muscles of upper limb
Muscles of lower limb (thigh)
Muscles of lower limb (leg)
MUSCLE
MAIN ACTION(S)
Deltoid
Raises your arm sideways at the shoulder
Biceps
Bends your arm at the elbow
Abdominals
Pull in your abdomen. Flex your trunk so you can bend
forward
Quadriceps
Straighten your leg at the knee and keep it straight when
you stand
Pectorals
Raises your arm at the shoulder. Draws it across your
chest
Latissimus dorsi
Pulls your arm down at the shoulder. Draws it behind your
back
Trapezius
Holds and rotates your shoulders. Moves your head back
and sideways
Triceps
Straightens your arm at the elbow
Gluteals
Pull your leg back at the hip. Raise it sideways at the hip.
Gluteus maximus is the biggest
Hamstrings
Bend your leg at the knee
gastrocnemius
Straightens the ankle joint so you can stand on tiptoes
Disorders relating to the Muscular
System
• Muscular Dystrophy: inherited, muscle
enlarge due to increased fat and connective
tissue, but fibers degenerate and atrophy
• Duchenne MD: lacking a protein to maintain
the sarcolemma
• Myasthenia Gravis: progressive weakness due
to a shortage of acetylcholine receptors
• Myositis ossificans
Duchenne
Myasthenia Gravis
Myositis ossificans
The end