1. Muscles
Chapter 10

2. Fasicle arrangement

3. 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

4. Parallel Muscles
Figure 11–1a

5. 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

6. Convergent Muscles

7. 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

8. Pennate Muscles
Figure 11–1c, d, e

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

10. Circular Muscles

11. 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)

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

13. 3 Classes of Levers
Depend on the relationship between applied force, fulcrum, and resistance:
first class
second class
third class

14. First-Class Levers
Figure 11–2a

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

16. Second–Class Levers

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

18. Third-Class Levers
Figure 11–2c

19. 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

20. Physics of levers

21. 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

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

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

24. Muscles: anterior

25. Muscles: posterior

26. Muscles of Facial Expression
Figure 11–4a

27. Muscles of Facial Expression
Figure 11–4b

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

29. Muscles of Mastication

30. Anterior Muscles of the Neck
Figure 11–9

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

32. Muscles of the Vertebral Column

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

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

35. The Appendicular Muscles
Figure 11–13a

36. The Appendicular Muscles

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

38. Muscles that Move the Arm

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

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

41. Muscles that Move the Hand and Fingers

42. Muscles that Move the Hand and Fingers

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

44. Muscles that Move the Thigh

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

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

47. Muscles that Move the Foot and Toes

48. Muscles that Move the Foot and Toes

49. Up next … Nervous System Histology