Download Muscular System

Lesson 1
- Types of Muscles
- Characteristics
PowerPoint® Lecture Slide Presentation
by Patty Bostwick-Taylor,
Florence-Darlington Technical College
The Muscular
System
6
PART A
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The Muscular System
 Muscles are responsible for all types of
body movement
 Three basic muscle types are found in the
body
 Skeletal muscle
 Cardiac muscle
 Smooth muscle
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Characteristics of Muscles
 Skeletal and smooth muscle cells are
elongated (muscle cell = muscle fiber)
 Contraction of muscles is due to the
movement of microfilaments
 All muscles share some terminology
 Prefixes myo and mys refer to “muscle”
 Prefix sarco refers to “flesh”
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Comparison of Skeletal, Cardiac,
and Smooth Muscles
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Table 6.1 (1 of 2)
Comparison of Skeletal, Cardiac,
and Smooth Muscles
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Table 6.1 (2 of 2)
Anatomical (structural) differences
(possible answers may include)
Cell shape and appearance
1. Skeletal muscles are multinucleate while
smooth and cardiac muscles are uninucleate
2. Skeletal & cardiac muscles have striations
while smooth do not
3. Only cardiac muscle has intercalated discs
Location
4. Skeletal muscle is attached to bones,
cardiac muscle is in the heart, smooth
muscle lines the walls of hollow organs (ex.
Digestive tract)
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Physiological (functional) differences
(possible answers may include)
Regulation of contraction
1. Skeletal muscle is under voluntary control
while smooth and cardiac muscle are under
involuntary control
Speed of contraction
2. Skeletal muscles can be slow or fast to
contract but cardiac muscles contract slow &
smooth muscles contract very slow.
Rhythm of contraction
3. Cardiac and some smooth muscles have
rhythmic contraction, skeletal does not
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Smooth Muscle Characteristics
 Lacks striations
 Spindle-shaped
cells
 Uninucleate
 Involuntary— no
conscious
control
 Found mainly in
the walls of
hollow organs
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Figure 6.2a
Cardiac Muscle Characteristics
 Striations
 Usually
uninucleate
 Branching cells
 Joined to another
muscle cell at an
intercalated disc
 Involuntary – no
conscious control
 Found only in the
heart
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Figure 6.2b
Skeletal Muscle Characteristics
 Most are attached by tendons to bones
 Cells are multinucleate
 Striated — have visible banding
 Voluntary — subject to conscious control
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Skeletal Muscle Attachments
 Epimysium blends into a connective tissue
attachment
 Tendons—cord-like structures that connect
muscle to bone
 Mostly collagen fibers
 Often cross a joint due to toughness and
small size
 Aponeuroses—sheet-like structures
 Attach muscles indirectly to bones,
cartilages, or connective tissue coverings
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Skeletal Muscle Attachments
 Sites of muscle attachment
 Bones
 Cartilages
 Connective tissue coverings
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Skeletal Muscle Functions
 Produce movement
 Maintain posture
 Stabilize joints
 Generate heat
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Lesson 2
- Skeletal Muscle Structure
- connective tissue wrappings
- microscopic anatomy
Connective Tissue Wrappings of Skeletal Muscle
 Cells are surrounded and bundled by connective
tissue
 Endomysium — encloses a single muscle fiber
 Perimysium — wraps around a fascicle
(bundle of muscle fibers)
 Epimysium — covers the entire skeletal
muscle
 Fascia — on the outside of the epimysium
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Connective Tissue Wrappings of Skeletal Muscle
Figure 6.1
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Microscopic Anatomy of Skeletal Muscle
 Sarcolemma— specialized plasma (cell)
membrane
 Myofibrils— long organelles inside muscle cell
 Sarcoplasmic reticulum— specialized smooth
endoplasmic reticulum
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Microscopic Anatomy of Skeletal Muscle Figure 6.3a
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Microscopic Anatomy of Skeletal Muscle
 Myofibrils are aligned to give distinct bands
 I band = light band
 Contains only thin filaments (actin)
 A band = dark band
 Contains the entire length of the thick
filaments (myosin)
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Microscopic Anatomy of Skeletal Muscle Figure 6.3b
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Microscopic Anatomy of Skeletal Muscle
 Sarcomere— contractile unit of a muscle fiber
 Organization of the sarcomere
 Thick filaments
 Composed of the protein myosin
 have heads (extensions, or cross bridges)
 Thin filaments
 Composed of the protein actin
 Anchored to the Z disc
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Microscopic Anatomy of Skeletal Muscle
Figure 6.3c
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Microscopic Anatomy of Skeletal Muscle
 At rest, there is a bare zone that lacks
actin filaments called the H zone
 Sarcoplasmic reticulum (SR)
 Stores and releases calcium
 Surrounds the myofibril
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Microscopic Anatomy of Skeletal Muscle
Figure 6.3d
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Lesson 3
- Muscle Stimulation
- stimulation & contraction
- nerve stimulus & action potential
- transmission of impulse to muscle
- sliding filament theory
Stimulation and Contraction of
Single Skeletal Muscle Cells
 Excitability (also called responsiveness or
irritability)—ability to receive and respond to a
stimulus
 Contractility—ability to shorten when an adequate
stimulus is received
 Extensibility—ability of muscle cells to be
stretched
 Elasticity—ability to recoil and resume resting
length after stretching
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The Nerve Stimulus and Action Potential
 Skeletal muscles must be stimulated by a
motor neuron (nerve cell) to contract
 Motor unit— one motor neuron and all the
skeletal muscle cells stimulated by that
neuron
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The Nerve Stimulus and Action Potential
Figure 6.4a
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The Nerve Stimulus and Action Potential
Figure 6.4b
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The Nerve Stimulus and Action Potential
 Neuromuscular junction
 Association site of axon terminal of the
motor neuron and muscle
 Synaptic cleft
 Gap between nerve and muscle
 Nerve and muscle do not make contact
 Area between nerve and muscle is filled
with interstitial fluid
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The Nerve Stimulus and Action Potential
Figure 6.5a
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The Nerve Stimulus and Action Potential
Synaptic cleft
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Figure 6.5b
Transmission of Nerve Impulse to Muscle
 Neurotransmitter—chemical released by nerve
upon arrival of nerve impulse
 Carries the impulse across the synaptic cleft
 The neurotransmitter for skeletal muscle is
acetylcholine (ACh)
 Acetylcholine attaches to receptors on the
sarcolemma of the muscle cells
 Sarcolemma becomes permeable to sodium
(Na+)
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Transmission of Nerve Impulse to Muscle
Figure 6.5c
 Sodium
rushes into
the cell
generating an
action
potential
 Once started,
muscle
contraction
cannot be
stopped
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Transmission of Nerve Impulse to Muscle
Figure 6.6
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The Sliding Filament Theory
of Muscle Contraction
 Activation by nerve causes myosin heads
(cross bridges) to attach to binding sites on the
thin filament; requires energy in form of ATP
 Myosin heads then pull thin filaments toward
the center of the sarcomere
 This continued action causes a sliding of the
actin past the myosin
 The result is that the muscle is shortened
(contracted)
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The Sliding Filament Theory
of Muscle Contraction
Video:
Sliding
Filament
Theory
Figure 6.7a–b
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The Sliding Filament Theory
Figure 6.8a
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The Sliding Filament Theory
Figure 6.8b
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The Sliding Filament Theory
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Figure 6.8c
Lesson 4
Contraction of Skeletal Muscle
Graded responses
Energy sources
Contraction of Skeletal Muscle
 Muscle fiber contraction is “all or none”
 Within a skeletal muscle, not all fibers may be
stimulated during the same interval
 Different combinations of muscle fiber
contractions may give differing responses
 Graded responses—different degrees of
skeletal muscle shortening
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Contraction of Skeletal Muscle
 Graded responses can be produced by
changing:
 The frequency of muscle stimulation
 The number of muscle cells being stimulated
at one time
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Types of Graded Responses
 Twitch
 Single, brief
contraction
 Not a normal
muscle function
Figure 6.9a
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Types of Graded Responses
 Tetanus (summing
of contractions)
 One contraction
is immediately
followed by
another
 The muscle does
not completely
return to a
resting state
 The effects are
added
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Figure 6.9b
Types of Graded Responses
 Unfused
(incomplete)
tetanus
 Some
relaxation
occurs
between
contractions
 The results are
summed
Figure 6.9c
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Types of Graded Responses
 Fused
(complete)
tetanus
 No relaxation
before the
following
contractions
 The result is
a sustained
muscle
contraction
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Figure 6.9d
Muscle Response to Strong Stimuli
 Muscle force depends upon the number of
fibers stimulated
 More fibers contracting results in greater
muscle tension
 Muscles can continue to contract unless they
run out of energy
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Energy for Muscle Contraction
 Initially, muscles use stored ATP for energy
 ATP bonds are broken to release energy
 Only 4–6 seconds worth of ATP is stored
by muscles
 After this initial time, other pathways must
be utilized to produce ATP
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Energy for Muscle Contraction
 Direct phosphorylation of ADP by creatine
phosphate (CP)
 Muscle cells store creatine phosphate
 CP is a high-energy molecule
 After ATP is depleted, ADP is left
 CP transfers energy to ADP, to regenerate ATP
 CP supplies are exhausted in less than 15
seconds
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Energy for Muscle Contraction
Figure 6.10a
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Energy for Muscle Contraction
 Aerobic respiration
 Glucose is broken down to carbon dioxide
and water, releasing energy (ATP)
 This is a slower reaction that requires
continuous oxygen
 A series of metabolic pathways occur in the
cell’s mitochondria
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Energy for Muscle Contraction
Figure 6.10b
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Energy for Muscle Contraction
 Anaerobic glycolysis and lactic acid formation
 Reaction that breaks down glucose without
oxygen
 Glucose is broken down to pyruvic acid to
produce a small amount of ATP
 Pyruvic acid is converted to lactic acid
 This reaction is not as efficient, but is fast
 Huge amounts of glucose are needed
 Lactic acid produces muscle fatigue
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Energy for Muscle Contraction
Figure 6.10c
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Muscle Fatigue and Oxygen Deficit
 When a muscle is fatigued, it is unable to
contract even with a stimulus
 Common cause for muscle fatigue is oxygen
debt
 Oxygen is required to get rid of accumulated
lactic acid
 Increasing acidity (from lactic acid) and lack of
ATP causes the muscle to contract less
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Types of Muscle Contractions
 Isotonic contractions
 Myofilaments are able to slide past each
other during contractions
 The muscle shortens and movement occurs
 Isometric contractions
 Tension in the muscles increases
 The muscle is unable to shorten or produce
movement
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Muscle Tone
 Some fibers are contracted even in a
relaxed muscle
 Different fibers contract at different times
to provide muscle tone
 The process of stimulating various fibers
is under involuntary control
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Lesson 5
Types of Movement
- Effect of Exercise on Muscles
- Muscles & Body Movements
- Types of Ordinary & Special
Movements
Effect of Exercise on Muscles
 Exercise increases muscle size, strength, and
endurance
 Aerobic (endurance) exercise (biking,
jogging) results in stronger, more flexible
muscles with greater resistance to fatigue
 Makes body metabolism more efficient
 Improves digestion and coordination
 Resistance (isometric) exercise (weight
lifting) increases muscle size and strength
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Effect of Exercise on Muscles
Figure 6.11
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Five Golden Rules of Skeletal Muscle Activity
Table 6.2
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Muscles and Body Movements
 Movement is due to a muscle pulling an
attached bone
 Muscles are attached to at least two points
 Origin
 Attachment to a moveable bone
 Insertion
 Attachment to an immovable / less
moveable bone
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Muscles and Body Movements
Figure 6.12
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Types of Ordinary Body Movements
 Flexion
 Decreases the angle of the joint
 Brings two bones closer together
 Typical of hinge joints like knee and elbow
 Extension
 Opposite of flexion
 Increases angle between two bones
 Hyperextension: increases angle of a joint
more than 180 degrees
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Types of Ordinary Body Movements
Figure 6.13a
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Types of Ordinary Body Movements
Figure 6.13b
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Types of Ordinary Body Movements
 Rotation
 Movement of a
bone around its
longitudinal axis
 Common in balland-socket joints
 Example: moving
the atlas around the
dens of axis (shake
your head “no”)
Figure 6.13c
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Types of Ordinary Body Movements
 Abduction
 Movement of a
limb away from
the midline
 Adduction
 Opposite of
abduction
 Movement of a
limb toward the
midline
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Figure 6.13d
Types of Ordinary Body Movements
 Circumduction
 Combination of
flexion,
extension,
abduction, and
adduction
 Common in
ball-and-socket
joints
Figure 6.13d
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Special Movements
 Dorsiflexion
 Lifting the foot so
that the superior
surface
approaches the
shin
 Plantar flexion
 Depressing the
foot (pointing the
toes)
Figure 6.13e
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Special Movements
 Inversion
 Turn sole
of foot
medially
 Eversion
 Turn sole
of foot
laterally
Figure 6.13f
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Special Movements
 Supination
 Forearm
rotates
laterally so
palm faces
anteriorly
 Pronation
 Forearm
rotates
medially so
palm faces
posteriorly
Figure 6.13g
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Special Movements
 Opposition
 Move thumb
to touch the
tips of other
fingers on
the same
hand
Figure 6.13h
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Lesson 6
Naming Skeletal Muscles
- Types of Muscles
- Naming Muscles
- Head and Neck Muscles
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
 Fixator—stabilizes the origin of a prime mover
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Naming Skeletal Muscles
 By direction of muscle fibers
 Example: Rectus (straight), Oblique
(diagonal)
 By relative size of the muscle
 Example: Maximus (largest), Longus (long)
 By location of the muscle
 Example: Temporalis (on temporal bone)
 By number of origins
 Example: Biceps (2 heads), Triceps (3 heads)
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Naming Skeletal Muscles
 By location of the muscle’s origin and insertion
 Example: Sternocleidomastoid (on the
sternum, clavicle, and mastoid process)
 By shape of the muscle
 Example: Deltoid (triangular)
 By action of the muscle
 Example: Flexor and extensor (flexes or
extends a bone)
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Arrangement
of Fascicles
Convergent – converge
toward tendon; fan shaped
Fusiform – spindle shape
with expanded midsection
Parallel – strap like
Circular – concentric rings
Unipennate – oblique
fibers from 1 side of tendon
Bipennate – oblique fibers
into opposite side of tendon
Multipennate – oblique
Figure 6.14
fibers
into several sides
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Head and Neck Muscles
 Facial muscles
 Frontalis— raises eyebrows
 Orbicularis oculi— closes eyes, squints,
blinks, winks
 Orbicularis oris— closes mouth and protrudes
the lips
 Buccinator— flattens the cheek, chews
 Zygomaticus— raises corners of the mouth
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Head and Neck Muscles
 Chewing muscles
 Masseter— closes the jaw raising the
mandible
 Temporalis— synergist of the masseter, aids
in closing the jaw
 Neck muscles
 Platysma— pulls the corners of the mouth
inferiorly
 Sternocleidomastoid—flexes the neck,
rotates the head
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Head and Neck Muscles
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Figure 6.15
Lesson 7
Skeletal Muscles
- Trunk Muscles
Muscles of Trunk, Shoulder, Arm
 Anterior muscles
 Pectoralis major— adducts and flexes the
humerus
 Intercostal muscles (rib cage)
 External intercostals— raise rib cage
during inhalation
 Internal intercostals— depress the rib
cage to move air out of the lungs during
exhalation
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Muscles of Trunk, Shoulder, Arm
 Muscles of the abdominal girdle
 Rectus abdominis—flexes vertebral column
and compresses abdominal contents
(defecation, childbirth, forced breathing)
 External and internal obliques—flex vertebral
column; rotate trunk and bend it laterally
 Transversus abdominis— compresses
abdominal contents
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Muscles of Trunk, Shoulder, Arm
 Posterior muscles
 Trapezius—elevates, depresses, adducts, and
stabilizes the scapula
 Latissimus dorsi—extends and adducts the
humerus
 Erector spinae— extension of back
 Quadratus lumborum—flexes the spine
laterally
 Deltoid—arm abduction
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Anterior Muscles of Trunk, Shoulder, Arm
1. Pectoralis major
2. Rectus abdominis
3. Transversus abdominis
4. Internal oblique
5. External oblique
6. Aponeurosis
Figure 6.16b
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Muscles of Posterior Neck, Trunk, Arm
Figure 6.17a
ANSWERS:
14. Occipital bone
15. Sternocleidomastoid
16. Trapezius
17. Deltoid
18. Spine of scapula
19. Deltoid (cut)
20. Triceps brachii
21. Latissimus dorsi
22. Humerus
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Muscles of Posterior Neck, Trunk, Arm
Figure 6.17b
ANSWERS:
23. Iliocostalis
24. Longissimus
25. Spinalis
26. Quadratus lumborum
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Lesson 8
Skeletal Muscles
- Limb Muscles
Muscles of the Upper Limb
 Biceps brachii— supination of forearm, flexion
of elbow
 Brachialis— elbow flexion
 Brachioradialis— weak muscle of forearm
 Triceps brachii— elbow extension (antagonist
to biceps brachii)
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Muscles of the Lower Limb
 Gluteus maximus— hip extension
 Gluteus medius—hip abduction, steadies
pelvis when walking
 Iliopsoas— hip flexion, keeps the upper
body from falling backward when standing
erect
 Adductor muscles— adduct the thighs
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Anterior Muscles of
Trunk, Shoulder, Arm
ANSWERS:
7. Clavicle
8. Deltoid
9. Sternum
10. Pectoralis major
11. Biceps brachii
12. Brachialis
13. Brachioradialis
Figure 6.16a
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Muscles of the Pelvis, Hip, Thigh
Answers:
27. Gluteus medius
28. Gluteus maximus
29. Adductor magnus
30. Iliotibial tract
31. Hamstring group
32. Gastrocnemius
Figure 6.19a
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Muscles of the Pelvis, Hip, Thigh
Answers:
33. Sartorius
34. Quadriceps
35. Adductor group
Figure 6.19c
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Muscles of the Lower Limb
 Muscles causing movement at the knee joint
 Hamstring group—thigh extension and
knee flexion
 Biceps femoris
 Semimembranosus
 Semitendinosus
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Muscles of the Lower Limb
 Muscles causing movement at the knee joint
 Sartorius—flexes the thigh
 Quadriceps group—extends the knee
 Rectus femoris (also flexes hip on thigh)
 Vastus muscles (three)
 Vastus medialis
 Vastus lateralis
 Vastus intermedius
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Muscles of the Lower Limb
 Muscles causing movement at ankle and foot
 Tibialis anterior— dorsiflexion and foot
inversion
 Extensor digitorum longus— toe extension
and dorsiflexion of the foot
 Fibularis muscles— plantar flexion and
eversion the foot
 Soleus— plantar flexion of foot
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Muscles of the
Lower Leg
Answers:
36. Fibularis longus
37. Fibularis brevis
38. Tibialis anterior
39. Extensor digitorum
longus
40. Fibularis tertius
Figure 6.20a
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Muscles of the Lower Leg
Figure 6.20b
Answers:
41. Gastrocnemius
42. Soleus
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Lesson 9
Skeletal Muscles
- Overview of all Superficial
Muscles
Superficial
Muscles: Anterior
Figure 6.21
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Superficial
Muscles: Anterior
Figure 6.21
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Superficial
Muscles: Anterior
Answers:
1. Temporalis
2. Masseter
3. Trapezius
4. Deltoid
5. Triceps brachii
6. Biceps brachii
7. Brachialis
8. Brachioradialis
9. Flexor carpi
ulnaris
10. Iliopsoas
11. Rectus femoris
12. Vastus lateralis
Answers:
13. Vastus medialis
14. Fibularis longus
15. Extensor digitorum
longus
16. Tibialis Anterior
17. Frontalis
18. Orbicularis oculi
19. Zygomaticus
20. Orbicularis oris
21. Platysma
22. Sternocleidomastoid
23. Pectoralis minor
24. Pectoralis major
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Answers:
25. Serratus anterior
26. Intercostals
27. Rectus
abdominus
28. External oblique
29. Internal oblique
30. Transverse
abdominus
31. Sartorius
32. Adductor muscle
33. Gracilis
34. Gastrocnemius
35. Soleus
Superficial
Muscles: Posterior
Figure 6.22
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Superficial
Muscles: Posterior
Figure 6.22
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Superficial
Muscles: Posterior
Answers:
1. Occipitalis
2. Sternocleidomastoid
3. Trapezius
4. Triceps brachii
5. Brachialis
6. Brachioradialis
7. Extensor carpi radialis longus
8. Flexor carpi ulnaris
9. Extensor carpi ulnaris
10. Extensor digitorum
11. Iliotibial tract
12. Gastrocnemius
Answers:
13. Soleus
14. Fibularis longus
15. Deltoid
16. Latissimus dorsi
17. Gluteus medius
18. Gluteus maximus
19. Adductor muscle
20. Biceps femoris
21. Semitendinosus
22. Semimembranosus
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Table 6.3 (1 of 3)
Superficial Anterior Muscles of the Body
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Table 6.3 (2 of 3)
Superficial Anterior Muscles of the Body
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Table 6.3 (3 of 3)
Superficial Anterior Muscles of the Body
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Table 6.4 (1 of 3)
Superficial Posterior Muscles of the Body
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Table 6.4 (2 of 3)
Superficial Posterior Muscles of the Body
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Table 6.4 (3 of 3)
Superficial Posterior Muscles of the Body
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Lesson 10
Developmental Aspects
- Muscle development
- Homeostatic Imbalances
Developmental Aspects of Muscular System
Embryo Development
 Muscular system is laid
down in segments
 Develops early in
pregnancy
 First movements of the
fetus, called
quickening, occur by
the 16th week of
pregnancy
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Developmental Aspects of Muscular System
Infancy
 Initial movements of baby are gross reflexes
 Nervous system must mature before baby can
control muscles
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Developmental Aspects of Muscular System
 Development proceeds in a
cephalic to caudal direction
 Gross muscular movements
precede fine motor
movements
 Can raise their head
before they sit up
 Can sit up before they can
walk
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Developmental Aspects of Muscular System
 Development also proceeds in a proximal to
distal direction
 Can wave bye-bye before can use pincher
grasp
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Developmental Aspects of Muscular System
As we age
 Amount of connective tissue in muscle
increases while amount of muscle tissue
decreases
 Body weight begins to decline in an older
person due to loss of muscle mass
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Developmental Aspects of Muscular System
 Muscle strength decreases by 50% by age 80
 Weight training can rebuild muscle mass and
increase strength in older people
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Homeostatic Imbalances
Duchenne’s Muscular Dystrophy
 Muscle destroying disease that progresses
from the extremities upward, final effects on
the head and chest muscles
 Caused by lack of muscle protein called
dystrophin that helps maintain the
sarcolemma
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Homeostatic Imbalances
Duchenne’s Muscular Dystrophy
 Almost exclusively in boys
(sex-linked genetic disorder)
 Diagnosed between age 2 – 7
 Active normal children
become clumsy and fall
frequently as muscles
weaken
 Rarely live beyond their 20s
 Die of respiratory failure
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Homeostatic Imbalances
 Myasthenia Gravis
 Rare disease that affects muscles during
adulthood, thought to be an autoimmune
disease
 Drooping of upper eyelids, difficulty
swallowing & talking, generalized muscle
weakness and fatigue
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Homeostatic Imbalances
 Myasthenia Gravis
 Shortage of acetylcholine receptors at
neuromuscular junctions
 Death usually due to respiratory failure
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Lesson 11 Review
Lesson 12 Exam