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Prepared by Patty Bostwick-Taylor,
Florence-Darlington Technical College
CHAPTER
6
The Muscular
System
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Characteristics of Muscles
•Skeletal and smooth muscle cells are
elongated (muscle cell = muscle fiber)
•Contraction and shortening 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”
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Table 6.1
Comparison of Skeletal, Cardiac,
and Smooth Muscles
Characteristic
Skeletal
Cardiac
Smooth
Body location
Attached to bone
or skin (for some
facial muscles)
Walls of the heart
Mostly in walls of
visceral organs
(other than the
heart)
Cell shape and
appearance
Single, very long,
cylindrical,
multinucleate
cells with very
obvious striations
Branching chains
of cells,
uninucleate,
striations,
intercalated discs
Single, fusiform,
uninucleate, no
striations
Connective
tissue
components
Endomysium,
perimysium, and
epimysium
Endomysium
Endomysium
© 2012 Pearson Education, Inc.
Comparison of Skeletal, Cardiac,
and Smooth Muscles
Characteristic
Skeletal
Cardiac
Smooth
Regulation of
contraction
Voluntary
Involuntary
Involuntary
Speed of
contraction
Slow to fast
Slow
Very slow
Rhythmic
contractions
No
Yes
Yes, in some
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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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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
© 2012 Pearson Education, Inc.
Muscle
fiber
(cell)
Blood vessel
Perimysium
Epimysium
(wraps entire
muscle)
Fascicle
(wrapped by
perimysium)
Endomysium
(between
fibers)
Tendon
Bone
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Figure 6.1
Skeletal Muscle Attachments
•Epimysium blends into a connective tissue
attachment
•Tendons—cord-like structures
•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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Smooth Muscle Characteristics
•Lacks striations
•Spindle-shaped cells
•Single nucleus
•Involuntary—no conscious control
•Found mainly in the walls of hollow organs
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Mucosa
Submucosa
Circular layer
of smooth muscle
(longitudinal view
of cells)
Longitudinal layer
of smooth muscle
(cross-sectional
view of cells)
(a)
© 2012 Pearson Education, Inc.
Figure 6.2a
Cardiac Muscle Characteristics
•Striations
•Usually has a single nucleus
•Branching cells
•Joined to another muscle cell at an
intercalated disc
•Involuntary
•Found only in the walls of the heart
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Cardiac
muscle
bundles
(b)
© 2012 Pearson Education, Inc.
Figure 6.2b
Skeletal Muscle Functions
•Produce movement
•Maintain posture
•Stabilize joints
•Generate heat
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Microscopic Anatomy of Skeletal Muscle
•Sarcolemma—specialized plasma membrane
•Myofibrils—long organelles inside muscle cell
•Sarcoplasmic reticulum—specialized smooth
endoplasmic reticulum
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Sarcolemma
Myofibril
Light
Dark
(A) band (I) band
Nucleus
(a) Segment of a muscle fiber (cell)
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Figure 6.3a
Microscopic Anatomy of Skeletal Muscle
•Myofibrils are aligned to give distinct bands
•I band = light band
•Contains only thin filaments
•A band = dark band
•Contains the entire length of the thick
filaments
© 2012 Pearson Education, Inc.
Z disc
H zone
Z disc
Thin (actin) filament
Thick (myosin) filament
(b) Myofibril or fibril
(complex organelle
composed of bundles
of myofilaments)
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I band
A band
I band
M line
Figure 6.3b
Microscopic Anatomy of Skeletal Muscle
•Sarcomere—contractile unit of a muscle fiber
•Organization of the sarcomere
•Myofilaments
•Thick filaments = myosin filaments
•Thin filaments = actin filaments
© 2012 Pearson Education, Inc.
Microscopic Anatomy of Skeletal Muscle
•Thick filaments = myosin filaments
•Composed of the protein myosin
•Has ATPase enzymes
•Myosin filaments have heads (extensions, or
cross bridges)
•Myosin and actin overlap somewhat
•Thin filaments = actin filaments
•Composed of the protein actin
•Anchored to the Z disc
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Sarcomere
Z disc
M line
Z disc
Thin (actin) filament
Thick (myosin) filament
(c) Sarcomere (segment of a myofibril)
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Figure 6.3c
Microscopic Anatomy of Skeletal Muscle
•Sarcoplasmic reticulum (SR)
•Stores and releases calcium
•Surrounds the myofibril
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Thick filament
Bare zone
Thin filament
(d) Myofilament structure (within one sarcomere)
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Figure 6.3d
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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Axon terminals at neuromuscular junctions
Spinal cord
Motor Motor
unit 1 unit 2
Nerve
Motor neuron
cell bodies
Muscle
Axon of
motor
neuron
Muscle fibers
(a)
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Figure 6.4a
Axon terminals at neuromuscular junctions
Muscle fibers
Branching axon
to motor unit
(b)
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Figure 6.4b
The Nerve Stimulus and Action Potential
•Neuromuscular junction
•Association site of axon terminal of the
motor neuron and muscle
PLAY
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A&P Flix™: Events at the Neuromuscular Junction
© 2012 Pearson Education, Inc.
Figure 6.5
The Nerve Stimulus and Action Potential
•Synaptic cleft
•Gap between nerve and muscle
•Nerve and muscle do not make contact
•Area between nerve and muscle is filled with
interstitial fluid
•Action potential reaches the axon terminal of
the motor neuron
•Calcium channels open and calcium ions enter
the axon terminal
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Transmission of Nerve Impulse to Muscle
•Calcium ion entry causes some synaptic
vesicles to release their contents
(acetylcholine, a neurotransmitter) by
exocytosis
•Neurotransmitter—chemical released by nerve
upon arrival of nerve impulse in the axon
terminal
•The neurotransmitter for skeletal muscle is
acetylcholine (ACh)
© 2012 Pearson Education, Inc.
Transmission of Nerve Impulse to Muscle
•Acetylcholine attaches to receptors on the
sarcolemma of the muscle cell
•In response to the binding of ACh to a
receptor, the sarcolemma becomes permeable
to sodium (Na+)
•Sodium rushes into the cell generating an
action potential and potassium leaves the cell
•Once started, muscle contraction cannot be
stopped
© 2012 Pearson Education, Inc.
Synaptic vesicle containing ACh
1 Action potential reaches axon
terminal of motor neuron.
Axon terminal of motor neuron
Mitochondrion
Ca2+
Synaptic
cleft
Ca2+
ACh
ACh
receptor
© 2012 Pearson Education, Inc.
Sarcolemma
Fusing synaptic
vesicle
Sarcoplasm
of muscle fiber
Folds of
sarcolemma
Figure 6.5, step 1
Synaptic vesicle containing ACh
1 Action potential reaches axon
terminal of motor neuron.
Axon terminal of motor neuron
Mitochondrion
2 Calcium (Ca2+) channels
open and Ca2+ enters the axon
terminal.
Ca2+
Synaptic
cleft
Ca2+
ACh
ACh
receptor
© 2012 Pearson Education, Inc.
Sarcolemma
Fusing synaptic
vesicle
Sarcoplasm
of muscle fiber
Folds of
sarcolemma
Figure 6.5, step 2
Synaptic vesicle containing ACh
1 Action potential reaches axon
terminal of motor neuron.
Axon terminal of motor neuron
Mitochondrion
2 Calcium (Ca2+) channels
open and Ca2+ enters the axon
terminal.
3 Ca2+ entry causes some
synaptic vesicles to release their
contents (acetylcholine, a
neurotransmitter) by exocytosis.
© 2012 Pearson Education, Inc.
Ca2+
Synaptic
cleft
Ca2+
ACh
ACh
receptor
Sarcolemma
Fusing synaptic
vesicle
Sarcoplasm
of muscle fiber
Folds of
sarcolemma
Figure 6.5, step 3
Synaptic vesicle containing ACh
1 Action potential reaches axon
terminal of motor neuron.
Axon terminal of motor neuron
Mitochondrion
2 Calcium (Ca2+) channels
open and Ca2+ enters the axon
terminal.
3 Ca2+ entry causes some
synaptic vesicles to release their
contents (acetylcholine, a
neurotransmitter) by exocytosis.
Ca2+
Synaptic
cleft
Ca2+
ACh
ACh
receptor
Sarcolemma
Fusing synaptic
vesicle
Sarcoplasm
of muscle fiber
Folds of
sarcolemma
4 Acetylcholine diffuses across
the synaptic cleft and binds to
receptors in the sarcolemma.
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Figure 6.5, step 4
5 ACh binds and channels open
that allow simultaneous passage
of Na+ into the muscle fiber and
K+ out of the muscle fiber. More
Na+ ions enter than K+ ions leave
and this produces a local change
in the electrical conditions of the
membrane (depolarization), which
eventually leads to an action
potential.
© 2012 Pearson Education, Inc.
Na+ K+
Ion channel in
sarcolemma opens;
ions pass.
Figure 6.5, step 5
ACh
Degraded ACh
Na+
Ion channel closed;
ions cannot pass.
6 ACh effects are ended by its
breakdown in the synaptic cleft by
the enzyme acetylcholinesterase.
Acetylcholinesterase
K+
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Figure 6.5, step 6
Neuromuscular junction
Nerve
fiber
Small twig
Match
flame
1 Flame ignites
the twig.
(a)
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Muscle cell
or fiber
Striations
1 Na+ diffuses
into the cell.
2 Action potential spreads
rapidly along the sarcolemma.
2 Flame spreads
rapidly along the twig.
(b)
Figure 6.6a-b
The Sliding Filament Theory
of Muscle Contraction
•Activation by nerve causes myosin heads
(cross bridges) to attach to binding sites on
the thin filament
•Myosin heads then bind to the next site of the
thin filament and pull them toward the center
of the sarcomere
•This continued action causes a sliding of the
myosin along the actin
•The result is that the muscle is shortened
(contracted)
© 2012 Pearson Education, Inc.
Actin
Myosin
Z
H
Z
I
A
I
(a)
Z
I
© 2012 Pearson Education, Inc.
(b)
Z
A
I
Figure 6.7a–b
Protein complex
(a)
Myosin
myofilament
© 2012 Pearson Education, Inc.
In a relaxed muscle cell, the regulatory proteins forming
part of the actin myofilaments prevent myosin binding
(see a). When an action potential (AP) sweeps along its
sarcolemma and a muscle cell is excited, calcium ions
(Ca2+) are released from intracellular storage areas (the
sacs of the sarcoplasmic reticulum).
Actin
myofilament
Figure 6.8a
Myosin-binding site
Ca2+
Upper part of thick filament only
The flood of calcium acts as the final trigger for
contraction, because as calcium binds to the regulatory
proteins on the actin filaments, the proteins undergo a
change in both their shape and their position on the thin
filaments. This action exposes myosin-binding sites on
the actin, to which the myosin heads can attach (see b),
and the myosin heads immediately begin seeking out
binding sites.
(b)
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Figure 6.8b
PLAY
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A&P Flix™: The Cross Bridge Cycle
Figure 6.8c
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 CP
•CP is a high-energy molecule
•After ATP is depleted, ADP is left
•CP transfers a phosphate group to ADP, to
regenerate ATP
•CP supplies are exhausted in less than 15
seconds
•About 1 ATP is created per CP molecule
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Figure 6.10a
Energy for Muscle Contraction
•Aerobic respiration
•Glucose is broken down to carbon dioxide
and water, releasing energy (about 32 ATP)
•A series of metabolic pathways occur in the
mitochondria
•This is a slower reaction that requires
continuous oxygen
•Carbon dioxide and water are produced
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Figure 6.10c
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 about 2 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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© 2012 Pearson Education, Inc.
Figure 6.10b
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 must be “repaid” to tissue to remove
oxygen deficit
•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
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Figure 6.11a-b
Skeletal Muscle
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Smooth Muscle
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Cardiac Muscle
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Five Golden Rules of Skeletal Muscle
Activity
1. With a few exceptions, all skeletal muscles
cross at least one joint.
2. Typically, the bulk of a skeletal muscle lies
proximal to the joint crossed.
3. All skeletal muscles have at least two
attachments: the origin and the insertion.
4. Skeletal muscles can only pull; they never
push.
5. During contraction, a skeletal muscle
insertion moves toward the origin.
© 2012 Pearson Education, Inc.
Muscles and Body Movements
•Movement is attained due to a muscle moving
an attached bone
•Muscles are attached to at least two points
•Origin
•Attachment to a moveable bone
•Insertion
•Attachment to an immovable bone
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Muscle
contracting
Origin
Brachialis
Tendon
Insertion
© 2012 Pearson Education, Inc.
Figure 6.12
Types of Body Movements
•Flexion
•Decreases the angle of the joint
•Brings two bones closer together
•Typical of bending hinge joints like knee and
elbow or ball-and-socket joints like the hip
•Extension
•Opposite of flexion
•Increases angle between two bones
•Typical of straightening the elbow or knee
•Extension beyond 180° is hypertension
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Figure 6.13a
© 2012 Pearson Education, Inc.
Figure 6.13b
Types of Body Movements
•Rotation
•Movement of a bone around its longitudinal
axis
•Common in ball-and-socket joints
•Example is when you move atlas around
the dens of axis (shake your head “no”)
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Figure 6.13c
Types of Body Movements
•Abduction
•Movement of a limb away from the midline
•Adduction
•Opposite of abduction
•Movement of a limb toward the midline
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Figure 6.13d
Types of Body Movements
•Circumduction
•Combination of flexion, extension,
abduction, and adduction
•Common in ball-and-socket joints
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© 2012 Pearson Education, Inc.
Figure 6.13d
Special Movements
•Dorsiflexion
•Lifting the foot so that the superior surface
approaches the shin (toward the dorsum)
•Plantar flexion
•Depressing the foot (pointing the toes)
•“Planting” the foot toward the sole
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© 2012 Pearson Education, Inc.
Figure 6.13e
Special Movements
•Inversion
•Turn sole of foot medially
•Eversion
•Turn sole of foot laterally
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© 2012 Pearson Education, Inc.
Figure 6.13f
Special Movements
•Supination
•Forearm rotates laterally so palm faces
anteriorly
•Radius and ulna are parallel
•Pronation
•Forearm rotates medially so palm faces
posteriorly
•Radius and ulna cross each other like an X
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Figure 6.13g
Special Movements
•Opposition
•Move thumb to touch the tips of other
fingers on the same hand
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Figure 6.13h
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
© 2012 Pearson Education, Inc.
(a) A muscle that crosses on the anterior side of a joint produces flexion*
Example:
Pectoralis
major
(anterior view)
© 2012 Pearson Education, Inc.
Figure 6.14a
(b) A muscle that crosses on the posterior side of a joint produces extension*
Example:
Latissimus
dorsi
(posterior
view)
© 2012 Pearson Education, Inc.
Figure 6.14b
(c) A muscle that crosses on the lateral side of a joint produces abduction
Example:
Medial deltoid
(anterolateral
view)
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Figure 6.14c
(d) A muscle that crosses on the medial side of a joint produces adduction
Example:
Teres major
(posterolateral
view)
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Figure 6.14d
Naming Skeletal Muscles
•By direction of muscle fibers
•Example: Rectus (straight)
•By relative size of the muscle
•Example: Maximus (largest)
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Naming Skeletal Muscles
•By location of the muscle
•Example: Temporalis (temporal bone)
•By number of origins
•Example: Triceps (three heads)
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Naming Skeletal Muscles
•By location of the muscle’s origin and insertion
•Example: Sterno (on the sternum)
•By shape of the muscle
•Example: Deltoid (triangular)
•By action of the muscle
•Example: Flexor and extensor (flexes or
extends a bone)
© 2012 Pearson Education, Inc.
Orbicularis oris
Deltoid
Pectoralis major
(d) Circular
(a) Convergent
(e) Multipennate
Biceps brachii
(d)
Rectus femoris
(e)
(a)
(b)
(b) Fusiform
(c)
(f) Bipennate
Sartorius
(f) Extensor digitorum
longus
(g)
© 2012 Pearson Education, Inc.
(c) Parallel
(g) Unipennate
Figure 6.15
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
•Chewing muscles
•Masseter—closes the jaw and elevates
mandible
•Temporalis—synergist of the masseter,
closes jaw
© 2012 Pearson Education, Inc.
Head and Neck Muscles
•Neck muscles
•Platysma—pulls the corners of the mouth
inferiorly
•Sternocleidomastoid—flexes the neck,
rotates the head
© 2012 Pearson Education, Inc.
Frontalis
Cranial
aponeurosis
Temporalis
Orbicularis
oculi
Occipitalis
Zygomaticus
Buccinator
Orbicularis
oris
Masseter
Sternocleidomastoid
Trapezius
Platysma
© 2012 Pearson Education, Inc.
Figure 6.16
Muscles of Trunk, Shoulder, Arm
•Anterior muscles
•Pectoralis major—adducts and flexes the
humerus
•Intercostal muscles
•External intercostals—raise rib cage
during inhalation
•Internal intercostals—depress the rib cage
to move air out of the lungs when you
exhale forcibly
© 2012 Pearson Education, Inc.
Clavicle
Deltoid
Sternum
Pectoralis
major
Biceps
brachii
Brachialis
Brachioradialis
(a)
© 2012 Pearson Education, Inc.
Figure 6.17a
Muscles of Trunk, Shoulder, Arm
•Muscles of the abdominal girdle
•Rectus abdominis—flexes vertebral column
and compresses abdominal contents
(defecation, childbirth, forced breathing)
•External oblique—flex vertebral column;
rotate trunk and bend it laterally
•Internal oblique—flex vertebral column;
rotate trunk and bend it laterally
•Transversus abdominis—compresses
abdominal contents
© 2012 Pearson Education, Inc.
Pectoralis
major
Rectus
abdominis
Transversus
abdominis
Internal
oblique
External
oblique
Aponeurosis
(b)
© 2012 Pearson Education, Inc.
Figure 6.17b
Muscles of Trunk, Shoulder, Arm
•Posterior muscles
•Trapezius—elevates, depresses, adducts,
and stabilizes the scapula
•Latissimus dorsi—extends and adducts the
humerus
•Erector spinae—back extension
•Quadratus lumborum—flexes the spine
laterally
•Deltoid—arm abduction
© 2012 Pearson Education, Inc.
Muscles of Trunk, Shoulder, Arm
•Muscles that arise from the shoulder girdle
and cross the shoulder joint to insert into the
humerus include:
•Pectoralis major
•Latissimus dorsi
•Deltoid
PLAY
A&P Flix™: Muscles that act on the shoulder joint and humerus:
An overview.
A&P Flix™: Muscles of the pectoral girdle.
PLAY
A&P Flix™: Muscles that cross the glenohumeral joint.
PLAY
A&P Flix™: Movement at the glenohumeral joint: An overview.
PLAY
© 2012 Pearson Education, Inc.
Occipital bone
Sternocleidomastoid
Trapezius
Spine of scapula
Deltoid (cut)
Deltoid
Triceps
brachii
Latissimus
dorsi
(a)
© 2012 Pearson Education, Inc.
Humerus
Olecranon
process of
ulna (deep
to tendon)
Figure 6.18a
C7
T1
Erector spinae
• Iliocostalis
• Longissimus
• Spinalis
Quadratus
Iumborum
(b)
© 2012 Pearson Education, Inc.
Figure 6.18b
Muscles of the Upper Limb
•Biceps brachii—supinates forearm, flexes
elbow
•Brachialis—elbow flexion
•Brachioradialis—weak muscle; elbow flexion
•Triceps brachii—elbow extension (antagonist
to biceps brachii)
PLAY
A&P Flix™: The elbow joint and forearm: An overview.
PLAY
A&P Flix™: Muscles of the elbow joint.
PLAY
A&P Flix™: Movement at the elbow joint.
© 2012 Pearson Education, Inc.
Clavicle
Deltoid
Sternum
Pectoralis
major
Biceps
brachii
Brachialis
Brachioradialis
(a)
© 2012 Pearson Education, Inc.
Figure 6.17a
Occipital bone
Sternocleidomastoid
Trapezius
Spine of scapula
Deltoid (cut)
Deltoid
Triceps
brachii
Latissimus
dorsi
(a)
© 2012 Pearson Education, Inc.
Humerus
Olecranon
process of
ulna (deep
to tendon)
Figure 6.18a
Muscles of the Upper Limb
•Muscles of the forearm, which insert on the
hand bones and cause their movement
include:
•Flexor carpi—wrist flexion
•Flexor digitorum—finger flexion
•Extensor carpi—wrist extension
•Extensor digitorum—finger extension
PLAY
A&P Flix™: Muscles that act on the wrist and fingers:
An overview.
A&P Flix™: Movements of the wrist and fingers (a).
PLAY
A&P Flix™: Movements of the wrist and fingers (b).
PLAY
© 2012 Pearson Education, Inc.
Muscles of the Lower Limb
•Muscles causing movement at the hip joint
include:
•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
PLAY
PLAY
A&P Flix™: Muscles that act on the hip joint and femur:
An overview.
A&P Flix™: Movement at the hip joint: An overview.
© 2012 Pearson Education, Inc.
Gluteus medius
Gluteus maximus
Adductor
magnus
Iliotibial tract
Biceps femoris
Semitendinosus
Hamstring group
Semimembranosus
Gastrocnemius
(a)
© 2012 Pearson Education, Inc.
Figure 6.20a
Posterior superior
iliac spine
IIiac crest
Safe area in
gluteus medius
Gluteus maximus
Sciatic nerve
(b)
© 2012 Pearson Education, Inc.
Figure 6.20b
12th
thoracic vertebra
12th rib
lliopsoas
Iliac crest
Psoas major
lliacus
5th
lumbar vertebra
Anterior superior
iliac spine
Quadriceps
Sartorius
Adductor
group
Rectus femoris
Vastus lateralis
Vastus medialis
Patella
Patellar
ligament
(c)
© 2012 Pearson Education, Inc.
Figure 6.20c
Muscles of the Lower Limb
•Muscles causing movement at the knee joint
•Hamstring group—thigh extension and knee
flexion
•Biceps femoris
•Semimembranosus
•Semitendinosus
© 2012 Pearson Education, Inc.
Gluteus medius
Gluteus maximus
Adductor
magnus
Iliotibial tract
Biceps femoris
Semitendinosus
Hamstring group
Semimembranosus
Gastrocnemius
(a)
© 2012 Pearson Education, Inc.
Figure 6.20a
Muscles of the Lower Limb
•Muscles causing movement at the knee joint
•Sartorius—flexes the thigh
•Quadriceps group—extends the knee
•Rectus femoris
•Vastus muscles (three)
PLAY
A&P Flix™: Muscles that cross the knee joint: An overview.
© 2012 Pearson Education, Inc.
12th
thoracic vertebra
12th rib
lliopsoas
Iliac crest
Psoas major
lliacus
5th
lumbar vertebra
Anterior superior
iliac spine
Quadriceps
Sartorius
Adductor
group
Rectus femoris
Vastus lateralis
Vastus medialis
Patella
Patellar
ligament
(c)
© 2012 Pearson Education, Inc.
Figure 6.20c
Inguinal
ligament
Adductor
muscles
Sartorius
Vastus
lateralis
(d)
© 2012 Pearson Education, Inc.
Figure 6.20d
Muscles of the Lower Limb
•Muscles causing movement at ankle and foot
•Tibialis anterior—dorsiflexion, foot inversion
•Extensor digitorum longus—toe extension
and dorsiflexion of the foot
•Fibularis muscles—plantar flexion, foot
eversion
•Soleus—plantar flexion
PLAY
A&P Flix™: Muscles that act on the ankle and foot:
An overview.
A&P Flix™: Posterior muscles that act on the ankle and foot.
PLAY
A&P Flix™: Movements of the ankle and foot.
PLAY
© 2012 Pearson Education, Inc.
Fibularis longus
Fibularis brevis
Tibialis anterior
Extensor digitorum
longus
Tibia
Soleus
Fibularis tertius
(a)
© 2012 Pearson Education, Inc.
Figure 6.21a
Gastrocnemius
Soleus
Calcaneal (Achilles)
tendon
Medial malleolus
Lateral
malleolus
(b)
© 2012 Pearson Education, Inc.
Figure 6.21b
Facial
• Frontalis
Facial
• Temporalis
• Orbicularis oculi
• Zygomaticus
• Masseter
• Orbicularis oris
Neck
• Platysma
• Sternocleidomastoid
Thorax
• Pectoralis minor
Shoulder
• Trapezius
• Deltoid
Arm
• Triceps brachii
• Biceps brachii
• Brachialis
Forearm
• Brachioradialis
• Flexor carpi radialis
• Pectoralis major
• Serratus anterior
• Intercostals
Abdomen
• Rectus abdominis
• External oblique
• Internal oblique
• Transversus abdominis
Pelvis/thigh
• lliopsoas
Thigh
• Sartorius
• Adductor muscle
Thigh (Quadriceps)
• Rectus femoris
• Vastus lateralis
• Vastus medialis
• Gracilis
Leg
• Fibularis longus
• Extensor digitorum longus
• Tibialis anterior
Leg
• Gastrocnemius
• Soleus
© 2012 Pearson Education, Inc.
Figure 6.22
Neck
• Occipitalis
• Sternocleidomastoid
• Trapezius
Arm
• Triceps brachii
• Brachialis
Forearm
• Brachioradialis
• Extensor carpi radialis
longus
• Flexor carpi ulnaris
• Extensor carpi ulnaris
• Extensor digitorum
Shoulder/Back
• Deltoid
• Latissimus dorsi
Hip
• Gluteus medius
• Gluteus maximus
lliotibial tract
Thigh
• Adductor muscle
• Hamstrings:
Biceps femoris
Semitendinosus
Semimembranosus
Leg
• Gastrocnemius
• Soleus
• Fibularis longus
Calcaneal
(Achilles)
tendon
© 2012 Pearson Education, Inc.
Figure 6.23
Deltoid
muscle
Humerus
© 2012 Pearson Education, Inc.
Figure 6.19
Posterior superior
iliac spine
IIiac crest
Safe area in
gluteus medius
Gluteus maximus
Sciatic nerve
(b)
© 2012 Pearson Education, Inc.
Figure 6.20b
Inguinal
ligament
Adductor
muscles
Sartorius
Vastus
lateralis
(d)
© 2012 Pearson Education, Inc.
Figure 6.20d