Transcript Chapter 11: The Muscular System

Chapter 11:
The Muscular System
1
The Muscular System
• Consists only of skeletal muscles
• Muscle organization affects power,
range, and speed of muscle movement
2
Fascicles
• Muscle cells (fibers) are organized in
bundles (fascicles)
• Classification of Skeletal Muscles
– By the way fascicles are organized
– By relationships of fascicles to tendons
3
Muscle Organization
• Groups of fibers are organized into fascicles
• Fibers in fascicle run parallel to fascicle,
but fascicle can be arranged in 4 different
shapes with respect to tendon:
1. Parallel Muscles
2. Convergent Muscles
3. Pennate Muscles
- Unipennate, Bipennate, Multipennate
4. Circular Muscles
4
1. Parallel Muscles
• Fascicles run parallel
to length of the
muscle
• Most skeletal muscles
are arranged this way
• Able to change length
extensively
• Can move load over a
great distance
5
Figure 11–1a
Parallel Muscle Body
• The center or body of the muscle
thickens when parallel muscle contracts
• Tension
– Depends on total number of myofibrils
• Directly relates to cross section of muscle
• 1 in.2 (6.45 cm2) of cross section develops 50 lb
(23 kg) of tension
6
2. Pennate Muscles
• Fascicles are arranged at an angle to tendon
A. Unipennate: Fascicle angled on one side of tendon
B. Bipennate: Tendon in middle with angled fascicles on either side
C. Multipennate:
- Branched tendon with fascicles organized around each branch
**Pennate muscles produce more tension than parallel muscles but
cannot move so far, less distance produced
A. Unipennate
B. Bipennate
C. Multipennate
7
Pennate Muscles
• Unipennate:
– fibers on 1 side of tendon
– e.g., extensor digitorum
• Bipennate:
– fibers on both sides of tendon
– e.g., rectus femoris
• Multipennate:
– tendon branches within muscle
– e.g., deltoid
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3. Convergent •
Muscles
Fascicles spread out
like a fan on one end
and converge to a
single point on the
other
• Produce less tension
and distance than
parallel muscles but
– Independent contraction
of fascicles can produce
different movement from
the same muscle
– Provides versatility
• Muscle fibers pull in
different directions,
depending on
stimulation
9
Figure 11–1b
4. Circular Muscles
• Also called sphincters
• Concentric
arrangement of
fascicles
• Function:
– Decrease diameter of
openings to guard
entrances and exits
• e.g., obicularis oris
10
Figure 11–1f
Why does a pennate muscle generate
more tension than does a parallel
muscle of the same size?
1. Parallel fibers do not respond to
calcium.
2. A pennate muscle contains more
muscle fibers.
3. Muscle force is concentrated on
the insertion in pennate muscles.
4. This is not a true statement.
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Which type of muscle would you expect
to be guarding the opening between the
stomach and the small intestine?
1.
2.
3.
4.
convergent muscle
multipennate muscle
parallel muscle
circular muscle (sphincter)
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Muscle Terminology
• Muscles have 1 fixed point of attachment (origin)
and 1 moving point of attachment (insertion)
• Origin:
– Where the fixed end of the muscle attached to bone,
cartilage, or CT
– Origin is usually proximal to insertion
• Insertion:
– Where the moveable end attaches
• Action:
– The specific movement produced by the muscle during
contraction
• e.g., flexion, extension, adduction, etc.
13
Muscles interact to produce or
oppose movements.
14
Muscle Interactions
• Muscles work in groups to maximize
efficiency
• Smaller muscles reach maximum
tension first, followed by larger,
primary muscles
15
Muscle Terminology
• Muscle often work in groups to increase tension or
fine tune movement
• Different muscles serve different function:
– Agonist:
• prime mover, muscle most responsible for the
movement
– Synergist:
• a muscle with the same action as the agonist
• assists agonist at the beginning of contraction when
fiber length is not optimal for agonist
– helps start motion or stabilize origin of agonist
(fixator)
– Antagonist:
• a muscle whose action opposes the agonist
– produces the opposite action to fine tune
16
movement by the agonist
Muscle Opposition
• Agonists and antagonists work in pairs:
– when 1 contracts, the other stretches
– i.e. flexors–extensors
abductors–adductors
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The name of a muscle helps
identify its location,
appearance, or function.
18
Descriptive Names
for Skeletal Muscles
1.
2.
3.
4.
5.
6.
Location in the body
Fascicle organization
Relative position
Structure, Size and Shape
Origin and insertion
Action
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Naming Muscles
•
Names of muscle are derived from aspects of
their features:
1. Location:
- Named for part of the body where they’re located
- e.g. Brachii, Abdominis
2. Fascicle Organization:
- Named for how fascicles are organized with respect
to the body
- e.g. Rectus = straight
Oblique = angle
3. Relative Position:
- Named for depth when layered
- e.g. Externus/Superficialis = top, surface
Internus/Profundus = deep
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Naming Muscles
4. Structure, Size and Shape:
A. Number of tendons
- e.g. triceps, biceps
B. Shape of Muscle
- e.g. trapezius = trapezoid
deltoid = triangle
soleus = fish
C. Size of muscle relative to others
- Major = bigger
- Maximus = biggest
- Longus = long
- Vastus = great
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Naming Muscles
5. Origin and Insertion:
- Name of regions of attachment, origin first,
insertion second
- e.g. sternocleidomastoid
Origin = manubrium of sternum and medial clavicle
Insertion = mastoid process
6. Action:
- Named for action performed and region
acted upon
- e.g. extensor digitorum
Usually multiple naming schemes are combined to name
the muscle:
e.g. flexor carpi ulnaris
* Individual muscles, orgins, insertions and actions are
examined in lab.
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Naming Skeletal Muscles
23
Table 11–1 (1 of 2)
Naming Skeletal Muscles
24
Table 11–1 (2 of 2)
Effects of Aging
on the Muscular System
1. Skeletal muscle fibers become
smaller in diameter
2. Skeletal muscles become less elastic:
–
develop increasing amounts of fibrous
tissue (fibrosis)
3. Decreased tolerance for exercise
4. Decreased ability to recover from
muscular injuries
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Muscle A abducts the humerus, and
muscle B adducts the humerus.
What is the relationship between
these two muscles?
1.
2.
3.
4.
synergists
antagonists
agonists
fixators
26
What does the name flexor carpi radialis
longus tell you about this muscle?
1.
2.
3.
4.
its size
its function
its location
1, 2, and 3 are correct
27
A Closer Look
at the Muscular System
28
Axial and Appendicular Muscles
29
Figure 11–3a
Axial and Appendicular Muscles
30
Figure 11–3b
Divisions of the Muscular System
1. Axial muscles:
–
–
–
position head and spinal column
move rib cage
60% of skeletal muscles
2. Appendicular muscles:
–
–
–
support pectoral and pelvic girdles
support limbs
40% of skeletal muscles
31
The Axial Muscles
• Divisions based on location and
function:
–
–
–
–
muscles of head and neck
muscles of vertebral column
oblique and rectus muscles
muscles of pelvic floor
32
Muscles of Facial Expression
33
Figure 11–4b
Summary: Muscles of Facial Expression
34
Table 11–2 (1 of 2)
Summary: Muscles of Facial Expression
35
Table 11–2 (2 of 2)
Anterior Muscles of the Neck
36
Figure 11–9
Oblique and Rectus Muscles
• Lie within the body wall
37
Figure 11–11a, b
Functions of
Oblique and Rectus Muscles
• Oblique muscles:
– compress underlying structures
– rotate vertebral column
• Rectus muscles:
– flex vertebral column
38
Oblique Muscles
• Thoracic region:
– intercostal muscles (external and internal
intercostals):
• respiratory movements of ribs
• Abdominopelvic region (same pattern
as thoracic):
– external oblique muscles
– internal oblique muscles
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Rectus Group
• Rectus abdominis:
– between xiphoid process and pubic
symphysis
– divided transversely by tendinous
inscriptions
40
Oblique Muscles
41
Table 11–9 (1 of 2)
Oblique and Rectus Muscles
42
Table 11–9 (2 of 2)
The structures
and functions of the
major muscle groups of
the upper and lower limbs.
43
The Appendicular Muscles
44
Figure 11–13b
The Appendicular Muscles
45
Figure 11–13a
The Appendicular Muscles
• Position and stabilize pectoral and
pelvic girdles
• Move upper and lower limbs
– Move the arm
– Move the forearm and hand
– Move the hand and fingers
46
Muscles that Position
the Pectoral Girdle
47
Figure 11–14b
Muscles that Position
the Pectoral Girdle
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Figure 11–14a
Muscles that Position the
Pectoral Girdle
• Trapezius:
– superficial
– covers back and neck to base of skull
– inserts on clavicles and scapular spines
• Rhomboid and levator scapulae:
– deep to trapezius
– attach to cervical and thoracic vertebrae
– insert on scapular border
• Serratus anterior:
– on the chest
– originates along ribs
– inserts on anterior scapular margin
49
Muscles that Position the
Pectoral Girdle
50
Tables 11–11
Muscles that Move the Arm
51
Figure 11–15a
Muscles that Move the Arm
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Figure 11–15b
9 Muscles that Move the Arm
• Deltoid:
– the major abductor (away from longitudinal
axis)
• Teres major/minor:
– produce rotation at shoulder
• Coracobrachialis:
– attaches to scapula
– produces flexion and adduction at shoulder
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9 Muscles that Move the Arm
• Pectoralis major:
– between anterior chest and greater
tubercle of humerus
– produces flexion at shoulder joint
• Latissimus dorsi:
– between thoracic vertebrae and humerus
– produces extension at shoulder joint
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The Rotator Cuff
• Muscles involved in shoulder rotation
– supraspinatus, subscapularis, infraspinatus,
teres minor,and their tendons
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Muscles that Move the Arm
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Table 11–12
Baseball pitchers sometimes suffer from
rotator cuff injuries. Which muscles are
involved in this type of injury?
1. rhomboid major and minor, teres
major and minor muscles
2. teres major, teres minor and
serratus anterior muscles
3. pectoralis major and minor muscles
4. supraspinatus, infraspinatus,
subscapularis, and teres minor
muscles
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Muscles that Move
the Forearm and Hand
58
Figure 11–16a
Muscles that Move
the Forearm and Hand
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Figure 11–16b
Muscles that Move
the Forearm and Hand
• Originate on humerus and insert on forearm
• Exceptions:
– the major flexor (biceps brachii)
• mainly on anterior and medial surfaces
– the major extensor (triceps brachii)
• mainly on posterior and lateral surfaces of arm
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Muscles that Move
the Forearm and Hand
• Biceps brachii:
–
–
–
–
flexes elbow
stabilizes shoulder joint
originates on scapula
inserts on radial tuberosity
• Triceps brachii:
– extends elbow
– originates on scapula
– inserts on olecranon
• Brachialis and brachioradialis:
– flex elbow
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Muscles that Move
the Forearm and Hand
• Flexor carpi ulnaris:
– superficial
– flexes wrist
– adducts wrist
• Flexor carpi radialis:
– superficial
– flexes wrist
– abducts wrist
• Extensor carpi radialis:
– superficial
– extends wrist
– abducts wrist
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Muscles that Move
the Forearm and Hand
• Extensor carpi ulnaris:
– superficial
– extends wrist
– adducts wrist
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Summary: Muscles that
Move the Forearm and Hand
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Table 11–13 (1 of 2)
Summary: Muscles that
Move the Forearm and Hand
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Table 11–13 (2 of 2)
Muscles that Move
the Hand and Fingers
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Figure 11–17a, b
Muscles that Move
the Hand and Fingers
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Figure 11–17c, d
Summary: Muscles that
Move the Hand and Fingers
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Muscles of the Pelvis
and Lower Limbs
• Pelvic girdle is tightly bound to axial
skeleton:
– permits little movement
– has few muscles
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Muscles that Position
the Lower Limbs
1. Muscles that move the thigh
2. Muscles that move the leg
3. Muscles that move the foot and toes
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Muscles that Move the Thigh
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Figure 11–19a, b
Muscles that Move the Thigh
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Figure 11–19c, d
Muscles that Move the Thigh
•
•
•
•
Gluteal muscles
Lateral rotators
Adductors
Iliopsoas
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Muscles that Move the Thigh
• Gluteal Muscles
– Gluteus maximus:
• largest, most posterior gluteal muscle
• produces extension and lateral rotation at hip
• Adductors
– Gracilis:
• hip flexion and adduction
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Muscles that Move the Leg
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Figure 11–20a
Muscles that Move the Leg
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Figure 11–20b, c
Muscles that Move the Leg
• Flexors of the knee:
– originate on the pelvic girdle
• Extensors of the knee:
– originate on the femoral surface
– insert on the patella
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Flexors and Extensors of the Knee
• Flexors of the Knee
–
–
–
–
Biceps femoris
Semimembranosus
Semitendinosus
Sartorius:
• originates superior to the acetabulum
• Extensors of the Knee
– 4 muscles of the quadriceps femoris:
• 3 vastus muscles
• rectus femoris muscle
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Hamstrings
• Hamstrings are made up of:
– biceps femoris
– semimembranosus
– semitendinosus
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Muscles that Move the Leg
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Table 11–17 (1 of 2)
Muscles that Move the Leg
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Table 11–17 (2 of 2)
You often hear of athletes who suffer a
pulled hamstring. To what does this
phrase refer?
1. biceps femoris, gracilis, and
adductor magnus damage
2. rectus femoris, vastus lateralis and
vastis medialis damage
3. semitendinosus, biceps femoris,
and semimembranosus muscle
damage
4. sartorius, gracilis and rectus
femoris damage
82
Muscles that Move
the Foot and Toes
83
Figure 11–21a, b
Muscles that Move
the Foot and Toes
84
Figure 11–21c, d
Muscles that Move
the Foot and Toes
• Extrinsic muscles that move the foot and
toes include:
–
–
–
–
muscles
muscles
muscles
muscles
that
that
that
that
produce
produce
produce
produce
extension at the ankle
flexion at the ankle
extension at the toes
flexion at the toes
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Muscles that Produce Movement
at the Ankle
• Muscles that Produce Extension at the Ankle
– Gastrocnemius
– Soleus
– Fibularis
– Tibialis posterior
• Muscles that Produce Flexion at the Ankle
– Tibialis anterior:
• opposes the gastrocnemius
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The Achilles Tendon
• The calcaneal tendon (Achilles
tendon):
– shared by the gastrocnemius and soleus
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Muscles the Produce Movement
of the Toes
• Muscles that Produce Extension at the
Toes
– Extensor digitorum longum
• Muscles that Produce Flexion at the Toes
– Flexor digitorum longum
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SUMMARY
• Effects of muscle structure on function
• Organization of skeletal muscle fibers:
– parallel, convergent, pennate, circular
• Relationships between levers and movement
• Actions of first, second, and third class
levers
• Origins and insertions of skeletal muscles
• Actions of skeletal muscles:
– agonist, antagonist, synergist
• How skeletal muscles are named
89
SUMMARY
• Structures and functions of axial muscles:
–
–
–
–
muscles of head and neck
muscle of vertebral column
oblique and rectus muscles
muscles of pelvic floor
• Structures and functions of the appendicular
muscles:
– muscles of shoulders and upper limbs
– muscles of pelvis and lower limbs
• Effects of aging on the muscular system
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