1. Chapter 11: The Muscular System Biol 141 A&P

2. The Muscular System Consists only of skeletal muscles
How are fascicles arranged in the various types of muscles, and what are the resulting functional differences?

3. Muscle Organization and Function
Muscle organization affects power, range, and speed of muscle movement
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. Organization of Skeletal Muscle Fibers
4 patterns of fascicle organization:
1) Parallel-
Fibers parallel to the long axis of muscle
- e.g., biceps brachii
2) Convergent-
3) Pennate-
4) Circular-

5. Parallel Muscles
Figure 11–1a

6. Parallel Muscle Body
The center or body of the muscle thickens when parallel muscle contracts
Parallel muscles contract about 30%
Parallel Muscle 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. Convergent Muscles
Figure 11–1b

8. Convergent Muscles
A broad area converges on attachment site (tendon, aponeurosis, or raphe)
Muscle fibers pull in different directions, depending on stimulation
e.g., pectoralis muscles

9. Pennate Muscles
Figure 11–1c, d, e

10. 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

11. Pennate Muscles Form an angle with the tendon
Do not move as far as parallel muscles
Contain more myofibrils than parallel muscles
Develop more tension than parallel muscles

12. Circular Muscles
Figure 11–1f

13. Circular Muscles Also called sphincters
Open and close to guard entrances of body
e.g., obicularis oris

14. Skeletal Motion Skeletal muscles attach to skeleton, produce motion
Type of muscle attachment affects power, range, and speed of muscle movement

15. What are the classes of levers, and how do they make muscles more efficient?
Mechanically, each bone is a lever (a rigid, moving structure):
and each joint a fulcrum (a fixed point)
Muscles provide applied force (AF):
required to overcome resistance (R)

16. Functions of a Lever To change: direction of an AF
distance and speed of movement produced by an AF
effective strength of an AF

17. 3 Classes of Levers
Depend on the relationship between applied force, fulcrum, and resistance:
first class
second class
third class
PLAY
First, Second, and Third-Class Levers

18. First-Class Levers
Figure 11–2a

19. First-Class Levers Seesaw is an example
Center fulcrum between applied force and resistance
Force and resistance are balanced

20. Second–Class Levers
Figure 11–2b

21. Second-Class Levers Wheelbarrow is an example
Center resistance between applied force and fulcrum
A small force moves a large weight

22. Third-Class Levers
Figure 11–2c

23. Third-Class Levers Most common levers in the body
Center applied force between resistance and fulcrum
Greater force moves smaller resistance
Maximizes speed and distance traveled

24. KEY CONCEPT Skeletal muscles can shorten to 70% of resting length
Power, speed, and range of movement
Depend on positions of muscle attachment
Relative to joints

25. How are actions of a muscle based on the relative positions of its origin and insertion?

26. Origins and Insertions
Muscles have 1 fixed point of attachment (origin) and 1 moving point of attachment (insertion)
Most muscles originate or insert on the skeleton
Origin is usually proximal to insertion

27. Actions Movements produced by muscle contraction Body movements
e.g., flexion, extension, adduction, etc.
Described in terms of bone, joint, or region

28. How do muscles interact to produce or oppose movements
How do muscles interact to produce or oppose movements? Muscle Interactions
Muscles work in groups to maximize efficiency
Smaller muscles reach maximum tension first, followed by larger, primary muscles

29. Muscle Terminology Based on Function
Agonist (prime mover):
produces a particular movement
Antagonist:
opposes movement of a particular agonist
Synergist:
a smaller muscle that assists a larger agonist
helps start motion or stabilize origin of agonist (fixator)

30. Muscle Opposition Agonists and antagonists work in pairs:
when 1 contracts, the other stretches
i.e., flexors–extensors, abductors–adductors, etc.

31. How does the name of a muscle help identify its location, appearance, or function?

32. Names of Skeletal Muscles
Correct names of muscles include the term muscle
Exceptions:
platysma
diaphragm

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

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

35. Descriptive Names for Skeletal Muscles
Location in the body-Identifies body regions: e.g.- temporalis muscle
Origin and insertion- First part of name indicates origin, Second part of name indicates insertion: e.g. genioglossus muscle
Fascicle organization-Describes fascicle orientation within muscle:
i.e., rectus (straight), transversus, oblique

36. Descriptive Names for Skeletal Muscles
4. Relative position- Externus (superficialis):
visible at body surface
Internus (profundus):deep muscles
Extrinsic:muscles outside an organ
Intrinsic:muscles inside an organ
5. Structural characteristics- Number of tendons:
bi = 2, tri = 3
Shape: trapezius, deltoid, rhomboid
Size-
6. Action- Movements: e.g., flexor, extensor, retractor
Occupations or habits: e.g., risor = laughter

37. Names for Muscle Size (1 of 2)
Longus = long
Longissimus = longest
Teres = long and round
Brevis = short
Magnus = large
Major = larger
Maximus = largest
Minor = small
Minimus = smallest

38. Axial and Appendicular Muscles
Figure 11–3a

39. Axial and Appendicular Muscles
Figure 11–3b

40. 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

41. What are the principle axial muscles of the body, their origins, insertions, actions, and innervation? 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

42. 6 Muscle Groups of the Head and Neck
Muscles of facial expression:
originate on skull
Extrinsic eye muscles:
originate on surface of orbit
control position of eye
3D Peel-Away of Muscles of the Head and Neck
PLAY

43. 6 Muscle Groups of the Head and Neck
Muscles of mastication:
move the mandible
Muscles of the tongue:
names end in glossus
Muscles of the pharynx:
begin swallowing process

44. 6 Muscle Groups of the Head and Neck
Anterior muscles of the neck:
control position of larynx
depress the mandible
support tongue and pharynx

45. Muscles of Facial Expression
Figure 11–4a

46. Muscles of Facial Expression
Figure 11–4b

47. Muscles of Facial Expression
Orbicularis oris:
constricts the mouth opening
Buccinator:
moves food around the cheeks
Muscles of the epicranium (scalp)

48. Muscles of the Epicranium (Scalp)
Temporoparietalis
Occipitofrontalis:
frontal and occipital bellies
separated by epicranial aponeurosis
Platysma:
covers anterior surface of neck

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

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

51. Extrinsic Eye Muscles
Also called extra-ocular muscles
Figure 11–5a, b

52. Extrinsic Eye Muscles Inferior rectus Medial rectus Superior rectus
Lateral rectus
Inferior oblique
Superior oblique
Figure 11–5c

53. Summary: Extrinsic Eye Muscles
Table 11–3

54. Muscles of Mastication
Figure 11–6

55. 3 Muscles of Mastication
Masseter:
the strongest jaw muscle
Temporalis:
helps lift the mandible
Pterygoid muscles:
position mandible for chewing

56. Summary: Muscles of Mastication
Table 11–4

57. Muscles of the Tongue
Figure 11–7

58. 4 Muscles of the Tongue Palatoglossus: Styloglossus: Genioglossus:
originates at palate
Styloglossus:
originates at styloid process
Genioglossus:
originates at chin
Hypoglossus:
originates at hyoid bone

59. Summary: Muscles of the Tongue
Table 11–5

60. Muscles of the Pharynx
Figure 11–8

61. 3 Muscles of the Pharynx Pharyngeal constrictor muscles:
move food into esophagus
Laryngeal elevator muscles:
elevate the larynx
Palatal muscles:
lift the soft palate

62. Summary: Muscles of the Pharynx
Table 11–6

63. Anterior Muscles of the Neck
Figure 11–9

64. 6 Anterior Muscles of the Neck
Digastric:
from chin to hyoid
and hyoid to mastoid
Mylohyoid:
floor of the mouth
Geniohyoid:
between hyoid and chin
Stylohyoid:
between hyloid and styloid
Sternocleidomastoid:
from clavicle and sternum to mastoid
Omohyoid:
attaches scapula, clavicle, first rib, and hyoid

65. Summary: Anterior Muscles of the Neck
Table 11–7

66. Muscles of the Vertebral Column
Figure 11–10a

67. Muscles of the Vertebral Column
Spinal extensors or erector spinae muscles (superficial and deep)
Spinal flexors (transversospinalis)

68. Superficial Spinal Extensors
Spinalis group
Longissimus group
Iliocostalis group
Deep Spinal Extensors
Semispinalis group
Multifidus muscle
Interspinalis muscles
Intertransversarii muscles
Rotatores muscles

69. Spinal Flexors Neck: Lumbar: longus capitis and longus colli
rotate and flex the neck
Lumbar:
quadratus lumborum muscles
flex spine and depress ribs

70. Summary: Muscles of the Vertebral Column
Table 11–8 (1 of 2)

71. Summary: Muscles of the Vertebral Column
Table 11–8 (2 of 2)

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

73. Oblique and Rectus Muscles
Figure 11–11a, c

74. Oblique and Rectus Muscles
Oblique muscles:
compress underlying structures
rotate vertebral column
Rectus muscles:
flex vertebral column
oppose erector spinae

75. Oblique Muscles Cervical region: Thoracic region: scalene muscles
flex the neck
Thoracic region:
intercostal muscles (external and internal intercostals):
respiratory movements of ribs
transversus thoracis:
cross inner surface of ribs

76. Oblique Muscles Abdominopelvic region (same pattern as thoracic):
external oblique muscles
internal oblique muscles
Transversus abdominis

77. Rectus Group Rectus abdominis: Diaphragmatic muscle or diaphragm:
between xiphoid process and pubic symphysis
divided longitudinally by linea alba
divided transversely by tendinous inscriptions
Diaphragmatic muscle or diaphragm:
divides thoracic and abdominal cavities
performs respiration

78. Summary: Oblique and Rectus Muscles
Table 11–9 (1 of 2)

79. Summary: Oblique and Rectus Muscles
Table 11–9 (2 of 2)

80. Muscles of the Pelvic Floor
Figure 11–12a

81. Muscles of the Pelvic Floor
Figure 11–12b

82. Functions of Pelvic Floor Muscles
Support organs of pelvic cavity
Flex sacrum and coccyx
Control movement of materials through urethra and anus

83. Perineum Pelvic Diaphragm
Muscular sheet forming the pelvic floor, divided into:
anterior urogenital triangle
posterior anal triangle
Pelvic Diaphragm
Deep muscular layer extending to pubis:
supports anal triangle

84. Urogenital Diaphragm Deep muscular layer between pubic bones:
supports the pelvic floor
and muscles of the urethra
Superficial muscles of the urogenital triangle:
support external genitalia

85. Summary: Muscles of the Pelvic Floor
Table (1 of 2)

86. Summary: Muscles of the Pelvic Floor
Table (2 of 2)

87. What are the principal appendicular muscles of the body and their origins, insertions, actions, and innervations?

88. The Appendicular Muscles
Figure 11–13a

89. The Appendicular Muscles
Figure 11–13b

90. The Appendicular Muscles
Position and stabilize pectoral and pelvic girdles
Move upper and lower limbs

91. Divisions of Appendicular Muscles
1) Muscles of the shoulders and upper limbs:
Position the pectoral girdle
Move the arm
Move the forearm and hand
Move the hand and fingers
2) Muscles of the pelvis and lower limbs

92. Muscles that Position the Pectoral Girdle
3D Peel-Away of Muscles of the Pectoral Girdle
PLAY
Figure 11–14a

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

94. 6 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

95. 6 Muscles that Position the Pectoral Girdle
Serratus anterior:
on the chest
originates along ribs
inserts on anterior scapular margin
Subclavius:
originates on ribs
inserts on clavicle
Pectoralis minor:
attaches to scapula

96. Summary: Muscles that Position the Pectoral Girdle
Tables 11–11

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

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

99. 9 Muscles that Move the Arm (1 of 3)
Deltoid:
the major abductor
Supraspinatus:
assists deltoid
Subscapularis and teres major:
produce medial rotation at shoulder
PLAY
3D Rotation: Muscles of the Arm

100. 9 Muscles that Move the Arm (2 of 3)
Infraspinatus and teres minor:
produce lateral rotation at shoulder
Coracobrachialis:
attaches to scapula
produces flexion and adduction at shoulder

101. 9 Muscles that Move the Arm (3 of 3)
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

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

103. Summary: Muscles that Move the Arm
Table 11–12

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

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

106. Muscles that Move the Forearm and Hand
Originate on humerus and insert on forearm
Exceptions:
the major flexor (biceps brachii)
the major extensor (triceps brachii)
3D Rotation: Muscles of the
Forearm and Hand
PLAY

107. Extensors and Flexors Extensors: Flexors:
mainly on posterior and lateral surfaces of arm
Flexors:
mainly on anterior and medial surfaces

108. 13 Muscles that Move the Forearm and Hand
Biceps brachii:
flexes elbow
stabilizes shoulder joint
Triceps brachii:
extends elbow
originates on scapula
inserts on olecranon
Brachialis and brachioradialis:
flex elbow
inserts on radial tuberosity

109. 13 Muscles that Move the Forearm and Hand
Anconeus:
opposes brachialis
Palmaris longus:
superficial
flexes wrist
Flexor carpi ulnaris:
adducts wrist

110. 13 Muscles that Move the Forearm and Hand
Flexor carpi radialis:
superficial
flexes wrist
abducts wrist
Extensor carpi radialis:
extends wrist
Extensor carpi ulnaris:
adducts wrist

111. 13 Muscles that Move the Forearm and Hand (8 of 8)
Pronator teres and supinator:
originate on humerus and ulna
rotate radius
Pronator quadratus:
originates on ulna
assists pronator teres

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

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

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

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

116. Muscles that Move the Hand and Fingers
Also called extrinsic muscles of the hand
Lie entirely within forearm
Only tendons cross wrist (in synovial tendon sheaths)

117. Tendon Sheaths Extensor retinaculum: Flexor retinaculum:
wide band of connective tissue
posterior surface of wrist
stabilizes tendons of extensor muscles
Flexor retinaculum:
anterior surface of wrist
stabilizes tendons of flexor muscles

118. Summary: Muscles that Move the Hand and Fingers
Table 11–14

119. The Intrinsic Muscles of the Hand
Figure 11–18a

120. The Intrinsic Muscles of the Hand
Figure 11–18b

121. Summary: The Intrinsic Muscles of the Hand
Table 11–15 (1of 2)

122. Summary: The Intrinsic Muscles of the Hand
Table 11–15 (2of 2)

123. Muscles of the Pelvis and Lower Limbs
Pelvic girdle is tightly bound to axial skeleton:
permits little movement
has few muscles
Muscles that Position the Lower Limbs
Muscles that move the thigh
Muscles that move the leg
Muscles that move the foot and toes

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

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

126. Muscles that Move the Thigh
Gluteal muscles
Lateral rotators
Adductors
Iliopsoas
PLAY
3D Peel-Away of Muscles of the Thigh
PLAY
3D Peel-Away of Rectus Muscle

127. Gluteal Muscles (1 of 2) Cover lateral surfaces of ilia
Gluteus maximus:
largest, most posterior gluteal muscle
produces extension and lateral rotation at hip

128. Gluteal Muscles (2 of 2) Tensor fasciae latae:
works with gluteus maximus
stabilizes iliotibial tract
Gluteus medius and gluteus minimus:
originate anterior to gluteus maximus
insert on trochanter

129. Lateral Rotators
Group of 6 muscles, including:
piriformis
obturator

130. Adductors Adductor magnus: Adductor brevis: Adductor longus:
produces adduction, extension, and flexion
Adductor brevis:
hip flexion and adduction
Adductor longus:
Pectineus:
Gracilis:

131. Iliopsoas
2 hip flexors insert on the same tendon:
psoas major
iliacus

132. Summary: Muscles that Move the Thigh
Table 11–16 (1 of 2)

133. Summary: Muscles that Move the Thigh
Table 11–16 (2 of 2)

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

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

136. 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

137. Flexors of the Knee Biceps femoris- Hamstrings Semimembranosus- “
Semitendinosus “
Sartorius:
originates superior to the acetabulum
Popliteus:
rotates the tibia to unlock the knee

138. Extensors of the Knee 4 muscles of the quadriceps femoris:
3 vastus muscles
rectus femoris muscle

139. Summary: Muscles that Move the Leg
Table 11–17 (1 of 2)

140. Summary: Muscles that Move the Leg
Table 11–17 (2 of 2)

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

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

143. 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

144. 4 Muscles that Produce Extension at the Ankle
Gastrocnemius
Soleus
Fibularis
Tibialis posterior
+ The Achilles Tendon-
The calcaneal tendon (Achilles tendon):
shared by the gastrocnemius and soleus

145. Muscles that Produce Flexion at the Ankle
Tibialis anterior:
opposes the gastrocnemius
Muscles that Produce Flexion at the Toes
Flexor digitorum longum
Flexor hallucis longus:
oppose the extensors

146. Muscles that Produce Extension at the Toes
Extensor digitorum longum
Extensor hallucis longus
Extensor retinacula:
fibrous sheaths hold tendons of toes as they cross the ankle

147. Summary: Muscles that Move the Foot and Toes
Table 11–18

148. The Intrinsic Muscles of the Foot
Figure 11–22a

149. The Intrinsic Muscles of the Foot
Figure 11–22b, c

150. Summary: The Intrinsic Muscles of the Foot
Table 11–19

151. 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

152. Integration with Other Systems
Figure 11–24

153. Integration with Other Systems
Cardiovascular system:
delivers oxygen and fuel
removes carbon dioxide and wastes
Respiratory system:
responds to oxygen demand of muscles
Integumentary system:
disperses heat from muscle activity
Nervous and endocrine systems:
direct responses of all systems

154. 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

155. 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