1. Chapter 11: The Muscular System

2. The Muscular System Consists only of skeletal muscles
Muscle organization affects power, range, and speed of muscle movement

3. 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

4. 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:
Parallel Muscles
Convergent Muscles
Pennate Muscles
- Unipennate, Bipennate, Multipennate
Circular Muscles

5. 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
Figure 11–1a

6. 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

7. 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
Unipennate
B. Bipennate
C. Multipennate

8. Pennate Muscles Unipennate: Bipennate: Multipennate:
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

9. 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
Figure 11–1b

10. 4. Circular Muscles Also called sphincters
Concentric arrangement of fascicles
Function:
Decrease diameter of openings to guard entrances and exits
e.g., obicularis oris
Figure 11–1f

11. Why does a pennate muscle generate more tension than does a parallel muscle of the same size?
Parallel fibers do not respond to calcium.
A pennate muscle contains more muscle fibers.
Muscle force is concentrated on the insertion in pennate muscles.
This is not a true statement.

12. Which type of muscle would you expect to be guarding the opening between the stomach and the small intestine?
convergent muscle
multipennate muscle
parallel muscle
circular muscle (sphincter)

13. 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.

14. Muscles interact to produce or oppose movements.

15. Muscle Interactions Muscles work in groups to maximize efficiency
Smaller muscles reach maximum tension first, followed by larger, primary muscles

16. 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 movement by the agonist

17. Muscle Opposition Agonists and antagonists work in pairs:
when 1 contracts, the other stretches
i.e. flexors–extensors
abductors–adductors
AnnMarie Armenti, MS SCCC BIO 130

18. The name of a muscle helps identify its location, appearance, or function.

19. Descriptive Names for Skeletal Muscles
Location in the body
Fascicle organization
Relative position
Structure, Size and Shape
Origin and insertion
Action

20. Naming Muscles
Names of muscle are derived from aspects of their features:
Location:
- Named for part of the body where they’re located
- e.g. Brachii, Abdominis
Fascicle Organization:
- Named for how fascicles are organized with respect to the body
- e.g. Rectus = straight
Oblique = angle
Relative Position:
- Named for depth when layered
- e.g. Externus/Superficialis = top, surface
Internus/Profundus = deep

21. Naming Muscles 4. Structure, Size and Shape: Number of tendons
- e.g. triceps, biceps
Shape of Muscle
e.g. trapezius = trapezoid
deltoid = triangle
soleus = fish
Size of muscle relative to others
Major = bigger
Maximus = biggest
Longus = long
Vastus = great

22. Naming Muscles 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.

23. Naming Skeletal Muscles
Table 11–1 (1 of 2)

24. Naming Skeletal Muscles
Table 11–1 (2 of 2)

25. Effects of Aging on the Muscular System
Skeletal muscle fibers become smaller in diameter
Skeletal muscles become less elastic:
develop increasing amounts of fibrous tissue (fibrosis)
Decreased tolerance for exercise
Decreased ability to recover from muscular injuries

26. Muscle A abducts the humerus, and muscle B adducts the humerus
Muscle A abducts the humerus, and muscle B adducts the humerus. What is the relationship between these two muscles?
synergists
antagonists
agonists
fixators

27. What does the name flexor carpi radialis longus tell you about this muscle?
its size
its function
its location
1, 2, and 3 are correct

28. A Closer Look
at the Muscular System

29. Axial and Appendicular Muscles
Figure 11–3a

30. Axial and Appendicular Muscles
Figure 11–3b

31. Divisions of the Muscular System
Axial muscles:
position head and spinal column
move rib cage
60% of skeletal muscles
Appendicular muscles:
support pectoral and pelvic girdles
support limbs
40% of skeletal muscles

32. 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

33. Muscles of Facial Expression
Figure 11–4b

34. Summary: Muscles of Facial Expression
Table 11–2 (1 of 2)

35. Summary: Muscles of Facial Expression
Table 11–2 (2 of 2)

36. Anterior Muscles of the Neck
Figure 11–9

37. Oblique and Rectus Muscles
Lie within the body wall
Figure 11–11a, b

38. Functions of Oblique and Rectus Muscles
Oblique muscles:
compress underlying structures
rotate vertebral column
Rectus muscles:
flex vertebral column

39. 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

40. Rectus Group Rectus abdominis:
between xiphoid process and pubic symphysis
divided transversely by tendinous inscriptions

41. Oblique Muscles
Table 11–9 (1 of 2)

42. Oblique and Rectus Muscles
Table 11–9 (2 of 2)

43. The structures and functions of the major muscle groups of the upper and lower limbs.

44. The Appendicular Muscles
Figure 11–13b

45. The Appendicular Muscles
Figure 11–13a

46. 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

47. Muscles that Position the Pectoral Girdle
Figure 11–14b

48. Muscles that Position the Pectoral Girdle
Figure 11–14a

49. 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

50. Muscles that Position the Pectoral Girdle
Tables 11–11

51. Muscles that Move the Arm
Figure 11–15a

52. Muscles that Move the Arm
Figure 11–15b

53. 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

54. 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

55. The Rotator Cuff Muscles involved in shoulder rotation
supraspinatus, subscapularis, infraspinatus, teres minor,and their tendons

56. Muscles that Move the Arm
Table 11–12

57. Baseball pitchers sometimes suffer from rotator cuff injuries
Baseball pitchers sometimes suffer from rotator cuff injuries. Which muscles are involved in this type of injury?
rhomboid major and minor, teres major and minor muscles
teres major, teres minor and serratus anterior muscles
pectoralis major and minor muscles
supraspinatus, infraspinatus, subscapularis, and teres minor muscles

58. Muscles that Move the Forearm and Hand
Figure 11–16a

59. Muscles that Move the Forearm and Hand
Figure 11–16b

60. 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

61. 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
inserts on olecranon
Brachialis and brachioradialis:
flex elbow

62. Muscles that Move the Forearm and Hand
Flexor carpi ulnaris:
superficial
flexes wrist
adducts wrist
Flexor carpi radialis:
abducts wrist
Extensor carpi radialis:
extends wrist

63. Muscles that Move the Forearm and Hand
Extensor carpi ulnaris:
superficial
extends wrist
adducts wrist

64. Summary: Muscles that Move the Forearm and Hand
Table 11–13 (1 of 2)

65. Summary: Muscles that Move the Forearm and Hand
Table 11–13 (2 of 2)

66. Muscles that Move the Hand and Fingers
Figure 11–17a, b

67. Muscles that Move the Hand and Fingers
Figure 11–17c, d

68. Summary: Muscles that Move the Hand and Fingers

69. Muscles of the Pelvis and Lower Limbs
Pelvic girdle is tightly bound to axial skeleton:
permits little movement
has few muscles

70. Muscles that Position the Lower Limbs
Muscles that move the thigh
Muscles that move the leg
Muscles that move the foot and toes

71. Muscles that Move the Thigh
Figure 11–19a, b

72. Muscles that Move the Thigh
Figure 11–19c, d

73. Muscles that Move the Thigh
Gluteal muscles
Lateral rotators
Adductors
Iliopsoas

74. 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

75. Muscles that Move the Leg
Figure 11–20a

76. Muscles that Move the Leg
Figure 11–20b, c

77. 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

78. 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

79. Hamstrings Hamstrings are made up of: biceps femoris semimembranosus
semitendinosus

80. Muscles that Move the Leg
Table 11–17 (1 of 2)

81. Muscles that Move the Leg
Table 11–17 (2 of 2)

82. You often hear of athletes who suffer a pulled hamstring
You often hear of athletes who suffer a pulled hamstring. To what does this phrase refer?
biceps femoris, gracilis, and adductor magnus damage
rectus femoris, vastus lateralis and vastis medialis damage
semitendinosus, biceps femoris, and semimembranosus muscle damage
sartorius, gracilis and rectus femoris damage

83. Muscles that Move the Foot and Toes
Figure 11–21a, b

84. Muscles that Move the Foot and Toes
Figure 11–21c, d

85. Muscles that Move the Foot and Toes
Extrinsic muscles that move the foot and toes include:
muscles that produce extension at the ankle
muscles that produce flexion at the ankle
muscles that produce extension at the toes
muscles that produce flexion at the toes

86. 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

87. The Achilles Tendon The calcaneal tendon (Achilles tendon):
shared by the gastrocnemius and soleus

88. 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

89. 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

90. 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
AnnMarie Armenti, MS SCCC BIO 130