1. Chapter 10
The Muscular System

2. An Introduction to the Muscular System
Consists only of skeletal muscles
Muscle Organization and Function
Muscle organization affects power, range, and speed of muscle movement
Fascicles
Muscle cells (fibers) are organized in bundles (fascicles)

3. Fascicle Arrangement Classification of Skeletal Muscles
By the way fascicles are organized
By relationships of fascicles to tendons

4. Fascicle Arrangement Organization of Skeletal Muscle Fibers
Four patterns of fascicle organization
Parallel
Convergent
Pennate
Circular

5. Fascicle Arrangement Parallel Muscles
Fibers parallel to the long axis of muscle
For example, biceps brachii
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. Muscle Types Based on Pattern of Fascicle Organization.
Fascicle Arrangement
[INSERT FIG. 11.1a]
Muscle Types Based on Pattern of Fascicle Organization.

7. Fascicle Arrangement Convergent Muscles
A broad area converges on attachment site (tendon, aponeurosis)
Muscle fibers pull in different directions, depending on stimulation
For example, pectoralis muscles

8. Fascicle Arrangement [INSERT FIG. 11.1b]
Muscle Types Based on Pattern of Fascicle Organization.

9. Fascicle Arrangement 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

10. Fascicle Arrangement Pennate Muscles Unipennate Bipennate Multipennate
Fibers on one side of tendon
For example, extensor digitorum
Bipennate
Fibers on both sides of tendon
For example, rectus femoris
Multipennate
Tendon branches within muscle
For example, deltoid

11. Fascicle Arrangement [INSERT FIG. 11.1c, d, e]
Muscle Types Based on Pattern of Fascicle Organization.

12. Fascicle Arrangement Circular Muscles Also called sphincters
Open and close to guard entrances of body
For example, orbicularis oris muscle of the mouth

13. Fascicle Arrangement
Muscle Types Based on Pattern of Fascicle Organization.

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

15. Levers
Levers
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. Levers Function of a lever is to change The Three Classes of Levers
Direction of an AF
Distance and speed of movement produced by an AF
Effective strength of an AF
The Three Classes of Levers
Depend on the relationship between applied force, fulcrum, and resistance
First class, second class, and third class

17. Levers First-Class Lever Seesaw or teeter-totter is an example
Center fulcrum between applied force and resistance
Force and resistance are balanced

18. The Three Classes of Levers.
[INSERT FIG. 11.2a]
The Three Classes of Levers.

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

20. Levers
[INSERT FIG. 11.2b]
Figure 11–2b The Three Classes of Levers.

21. Levers 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

22. Levers
[INSERT FIG. 11.2c]
The Three Classes of Levers.

23. Muscle Attachments to Other Tissues
Origins and Insertions
Muscles have one fixed point of attachment (origin) and one moving point of attachment (insertion)
Most muscles originate or insert on the skeleton
Origin is usually proximal to insertion

24. Muscle Attachments to Other Tissues
Actions
Movements produced by muscle contraction
Body movements
For example, flexion, extension, adduction, etc.
Described in terms of bone, joint, or region

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

26. Muscle Attachments to Other Tissues
Muscle Terminology Based on Function
Agonist (or 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)

27. Muscle Attachments to Other Tissues
Muscle Opposition
Agonists and antagonists work in pairs:
When one contracts, the other stretches
Such as flexors–extensors, abductors–adductors, etc.

28. Naming Skeletal Muscles
Names of Skeletal Muscles
Correct names of muscles include the term muscle
Exceptions
Platysma
Diaphragm

29. Naming Skeletal Muscles
Descriptive Names for Skeletal Muscles
Location in the body
Origin and insertion
Fascicle organization
Relative position
Structural characteristics
Action

30. Naming Skeletal Muscles
Location in the Body
Identifies body regions
For example, temporalis muscle
Origin and Insertion
First part of name indicates origin
Second part of name indicates insertion
For example, genioglossus muscle

31. Naming Skeletal Muscles
Fascicle Organization
Describes fascicle orientation within muscle
i.e., rectus (straight), transversus, oblique

32. Naming Skeletal Muscles
Relative Position
Externus (superficialis)
Visible at body surface
Internus (profundus)
Deep muscles
Extrinsic
Muscles outside an organ
Intrinsic
Muscles inside an organ

33. Naming Skeletal Muscles
Structural Characteristics
Number of tendons
bi = 2, tri = 3
Shape
Trapezius, deltoid, rhomboid
Size
Many terms refer to muscle size

34. Naming Skeletal Muscles
Descriptive Terms for Muscle Size
Longus = long
Longissimus = longest
Teres = long and round
Brevis = short
Magnus = large
Major = larger
Maximus = largest
Minor = small
Minimus = smallest

35. Naming Skeletal Muscles
Action
Movements
For example, flexor, extensor, retractor
Occupations or habits
For example, risor = laughter

36. Muscular System Overview
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

37. Muscular System Overview

38. Muscular System Overview

39. Muscular System Overview

40. Muscular System Overview

41. Axial Musculature
Muscles of Facial Expression.

42. Axial Musculature Six Extrinsic Eye Muscles (Extra ocular)
Inferior rectus
Medial rectus
Superior rectus
Lateral rectus
Inferior oblique
Superior oblique

43. Axial Musculature
Extrinsic Eye Muscles.

44. Axial Musculature [INSERT FIG. 11.11a]
Oblique and Rectus Muscles and the Diaphragm.

45. Axial Musculature [INSERT FIG. 11.11b]
Oblique and Rectus Muscles and the Diaphragm.

46. Axial Musculature [INSERT FIG. 11.11c]
Oblique and Rectus Muscles and the Diaphragm.

47. Axial Musculature Muscles of the Pelvic Floor
Functions of pelvic floor muscles
Support organs of pelvic cavity
Flex sacrum and coccyx
Control movement of materials through urethra and anus

48. Axial Musculature
[INSERT FIG a]
Muscles of the Pelvic Floor.

49. Axial Musculature
[INSERT FIG b]
Muscles of the Pelvic Floor.

50. Appendicular Musculature
[INSERT FIG a]
Muscles That Position the Pectoral Girdle.

51. Appendicular Musculature
[INSERT FIG b]
Muscles That Position the Pectoral Girdle.

52. Appendicular Musculature
Muscles That Move the Arm.

53. Appendicular Musculature
Muscles That Move the Forearm and Hand.

54. Appendicular Musculature
Muscles That Move the Forearm and Hand.

55. Appendicular Musculature
[INSERT FIG a]
Muscles That Move the Hand and Fingers.

56. Appendicular Musculature
Intrinsic Muscles of the Hand.

57. Appendicular Musculature
Intrinsic Muscles of the Hand.

58. Appendicular Musculature
Muscles That Move the Thigh.

59. Appendicular Musculature
[INSERT FIG b]
Muscles That Move the Thigh.

60. Appendicular Musculature
[INSERT FIG c]
Muscles That Move the Thigh.

61. Appendicular Musculature
[INSERT FIG b]
Muscles That Move the Leg.

62. Appendicular Musculature
[INSERT FIG d]
Muscles That Move the Thigh.

63. Appendicular Musculature
Muscles That Move the Leg.

64. Appendicular Musculature
Extrinsic Muscles That Move the Foot and Toes.

65. Appendicular Musculature
[INSERT FIG b]
Extrinsic Muscles That Move the Foot and Toes.

66. Appendicular Musculature
[INSERT FIG b]
Intrinsic Muscles of the Foot.