1. دکترامیر هوشنگ واحدی متخصص طب فیزیکی و توانبخشی قسمت 1
body muscels system 1
دکترامیر هوشنگ واحدی
متخصص طب فیزیکی و توانبخشی
قسمت 1

4. B. Anatomy of Skeletal Muscles - Gross Anatomy
Surrounds muscle
Bundle of muscle fibers
Surrounds each muscle fiber, and tie adjacent fibers together
Divides muscle into compartments, each contain a bundle of muscle fibers called fascicle

5. Structural Organization of Skeletal Muscle
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Structural Organization of Skeletal Muscle

6. The Formation and Structure of a Skeletal Muscle Fiber

7. Development of a skeletal muscle fiber
Sarcomere Structure
Fig 9.4

8. Levels of Functional Organization in a Skeletal Muscle Fiber
Muscle Fascicle
Muscle Fiber
Myofibril
Sacromere

9. Orientation of the SR, T Tubules, and Individual Sacromeres

10. Thin and Thick Filaments

11. Changes in the appearance of a sarcomere during contraction of a skeletal muscle fiber
During a contraction, the A band stays the same width, but the Z lines move closer together and the I band and H band are reduced in width

12. The Effect of Sarcomere Length on Tension

13. The Neuromuscular Synapse

14. The Events in Muscle Contraction

15. The Arrangement of Motor Units in a Skeletal Muscle

16. Nerve Stimulus to Muscles
Skeletal muscles must be stimulated by a nerve to contract
Motor unit
One neuron
Muscle cells stimulated by that neuron

19. Neuromuscular junction, microscopic view

20. Skeletal Muscle Innervation
Each muscle fiber is stimulated by a nerve fiber usually located midway along its length
- the synaptic terminal of the neuron is bound to the motor end plate (specialized area of the muscle cell membrane)
- entensive vascular supply delivers oxygen and nutrients

21. The Neuromuscular Junction
axon
axon terminal
motor unit
1 neuron and all the muscles it stimulates

22. The Sliding Filament Theory of Muscle Contraction
Activation by nerve causes myosin heads (crossbridges) to attach to binding sites on the thin filament
Myosin heads then bind to the next site of the thin filament
Figure 6.7
Slide 6.17a

23. The Sliding Filament Theory of Muscle Contraction
This continued action causes a sliding of the myosin along the actin
The result is that the muscle is shortened (contracted)

24. The Sliding Filament Theory

25. Contraction of a Skeletal Muscle
Muscle fiber contraction is “all or none”
Within a skeletal muscle, not all fibers may be stimulated during the same interval
Different combinations of muscle fiber contractions may give differing responses
Graded responses – different degrees of skeletal muscle shortening

26. Energy for Muscle Contraction
Initially, muscles used stored ATP for energy
Bonds of ATP are broken to release energy
Only 4-6 seconds worth of ATP is stored by muscles
After this initial time, other pathways must be utilized to produce ATP

27. Energy for Muscle Contraction
Direct phosphorylation
Muscle cells contain creatine phosphate (CP)
CP is a high-energy molecule
After ATP is depleted, ADP is left
CP transfers energy to ADP, to regenerate ATP
CP supplies are exhausted in about 20 seconds

28. Energy for Muscle Contraction
Aerobic Respiration
Series of metabolic pathways that occur in the mitochondria
Glucose is broken down to carbon dioxide and water, releasing energy
This is a slower reaction that requires continuous oxygen

29. Energy for Muscle Contraction
Anaerobic glycolysis
Reaction that breaks down glucose without oxygen
Glucose is broken down to pyruvic acid to produce some ATP
Pyruvic acid is converted to lactic acid

30. Energy for Muscle Contraction
Anaerobic glycolysis (continued)
This reaction is not as efficient, but is fast
Huge amounts of glucose are needed
Lactic acid produces muscle fatigue

31. Muscle Fatigue and Oxygen Debt
When a muscle is fatigued, it is unable to contract
The common reason for muscle fatigue is oxygen debt
Oxygen must be “repaid” to tissue to remove oxygen debt
Oxygen is required to get rid of accumulated lactic acid
Increasing acidity (from lactic acid) and lack of ATP causes the muscle to contract less
Slide 6.27
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

32. Types of Muscle Contractions
Isotonic contractions
Myofilaments are able to slide past each other during contractions
The muscle shortens
Isometric contractions
Tension in the muscles increases
The muscle is unable to shorten
Slide 6.28
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

33. Muscle Tone Some fibers are contracted even in a relaxed muscle
Different fibers contract at different times to provide muscle tone
The process of stimulating various fibers is under involuntary control
Slide 6.29
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

34. Muscles and Body Movements
Movement is attained due to a muscle moving an attached bone

35. Muscles and Body Movements
Muscles are attached to at least two points
Origin – attachment to a moveable bone
Insertion – attachment to an immovable bone

36. Effects of Exercise on Muscle
Results of increased muscle use
Increase in muscle size
Increase in muscle strength
Increase in muscle efficiency
Muscle becomes more fatigue resistant

37. Calcium Troponin-Tropomyosin Interaction

38. Results of actin-myosin interaction

39. Action Potentials on the Sarcolemma

40. Skeletal Muscles
Responsible for movement of body and all of its joints
Muscle contraction produces force that causes joint movement
Muscles also provide
protection
posture and support
produce a major portion of total body heat

41. Skeletal Muscles
Over 600 skeletal muscles comprise approximately 40 to 50% of body weight
215 pairs of skeletal muscles usually work in cooperation with each other to perform opposite actions at the joints which they cross
Aggregate muscle action - muscles work in groups rather than independently to achieve a given joint motion

42. Muscle Nomenclature Muscles are usually named due to
visual appearance
anatomical location
function
Shape – deltoid, rhomboid
Size – gluteus maximus, teres minor
Number of divisions – triceps brachii
Direction of its fibers – external oblique

43. Muscle Nomenclature Location - rectus femoris, palmaris longus
Points of attachment - coracobrachialis, extensor hallucis longus, flexor digitorum longus
Action - erector spinae, supinator, extensor digiti minimi
Action & shape – pronator quadratus

44. Muscle Nomenclature Action & size – adductor magnus
Shape & location – serratus anterior
Location & attachment – brachioradialis
Location & number of divisions – biceps femoris

45. Shape of Muscles & Fiber Arrangement
Cross section diameter
factor in muscle’s ability to exert force
greater cross section diameter = greater force exertion
Muscle’s ability to shorten
longer muscles can shorten through a greater range
more effective in moving joints through large ranges of motion

46. Shape of Muscles & Fiber Arrangement
2 major types of fiber arrangements
parallel & pennate
each is further subdivided according to shape
Parallel muscles
fibers arranged parallel to length of muscle
produce a greater range of movement than similar sized muscles with pennate arrangement

47. Fiber Arrangement - Parallel
Categorized into following shapes
Flat
Fusiform
Strap
Radiate
Sphincter or circular

48. Fiber Arrangement - Parallel
Flat muscles
usually thin & broad, originating from broad, fibrous, sheet-like aponeuroses
allows them to spread their forces over a broad area
Ex. rectus abdominus & external oblique

49. Fiber Arrangement - Parallel
Fusiform muscles
spindle-shaped with a central belly that tapers to tendons on each end
allows them to focus their power onto small, bony targets
Ex. brachialis, biceps brachii

50. Fiber Arrangement - Parallel
Strap muscles
more uniform in diameter with essentially all fibers arranged in a long parallel manner
enables a focusing of power onto small, bony targets
Ex. sartorius

51. Fiber Arrangement - Parallel
Radiate muscles
also described sometimes as being triangular, fan-shaped or convergent
have combined arrangement of flat & fusiform
originate on broad aponeuroses & converge onto a tendon
Ex. pectoralis major, trapezius

52. Fiber Arrangement - Parallel
Sphincter or circular muscles
technically endless strap muscles
surround openings & function to close them upon contraction
Ex. orbicularis oris surrounding the mouth

53. Fiber Arrangement - Pennate
Pennate muscles
have shorter fibers
arranged obliquely to their tendons in a manner similar to a feather
arrangement increases the cross sectional area of the muscle, thereby increasing the power

54. Fiber Arrangement - Pennate
Categorized based upon the exact arrangement between fibers & tendon
Unipennate
Bipennate
Multipennate

55. Fiber Arrangement - Pennate
Unipennate muscles
fibers run obliquely from a tendon on one side only
Ex. biceps femoris, extensor digitorum longus, tibialis posterior

56. Fiber Arrangement - Pennate
Bipennate muscle
fibers run obliquely on both sides from a central tendon
Ex. rectus femoris, flexor hallucis longus

57. Fiber Arrangement - Pennate
Multipennate muscles
have several tendons with fibers running diagonally between them
Ex. deltoid
Bipennate & unipennate produce strongest contraction