1. Chapter 7
The Muscular System

2. Types of Muscle
Smooth
Cardiac
Skeletal

3. Smooth Muscle Makes up walls of hollow body organs,
respiratory passageways
Involuntary movement
Cell structure
Tapered ends
Single, central nucleus
No visible bands (striations)
Stimulated by nerve impulses, hormones, stretching

4. Cardiac Muscle Makes up wall of heart Involuntary movement
Cell structure
Branching interconnections
Single, central nucleus
Striated
Membranes are intercalated disks
Stimulated by electrical impulses, nervous stimuli, hormones

5. Skeletal Muscle Attached to bones, muscles, or skin Voluntary movement
Cell structure
Long and cylindrical
Multiple nuclei per cell
Heavily striated
Stimulated by nervous system

7. Checkpoint 7-1: What are the three types of muscle?
Smooth
Cardiac
skeletal

8. The Muscular System Skeletal muscle has three primary functions
Skeletal movement
Posture maintenance
Heat generation

9. Checkpoint 7-2: What are the three main functions of skeletal muscle?
Skeletal movement
Posture maintenance
Heat generation

10. Structure of a Muscle Connective tissue layers Tendon Endomysium
Around individual fibers
Perimysium
Around fascicles (bundles of muscle fibers)
Epimysium
Over entire muscle
Part of deep fascia
Tendon
Attaches muscle to bone

11. Structure of a skeletal muscle.
ZOOMING  IN • What is the innermost layer of connective tissue in a muscle?
The endomysium
What layer of connctive tissue surrounds a fascicle of muscle fibers?
The perimysium

12. Muscle Cells in Action
Motor unit is a single neuron and all the muscle fibers it stimulates
Neuromuscular junction (NMJ)
Neurotransmitter
Synaptic cleft
Receptors
Motor end plate

13. Nervous stimulation of skeletal muscle.

14. Neuromuscular junction (NMJ).

15. Checkpoint 7-3: Muscles are activated by the nervous system
Checkpoint 7-3: Muscles are activated by the nervous system. What is the name of the special synapse where a nerve cell makes contact with a muscle cell?
The neuromuscular junction
Checkpoint 7-4: What neurotransmitter is involved in the stimulation of skeletal muscle cells?
Acetylcholine

16. Properties of Muscle Tissue
Excitability
Action potential
Contractility
Actin
Myosin
Sarcomere
ATP

17. Electron microscope photograph of skeletal muscle cell (x6500).

18. Sliding filament mechanism of skeletal muscle contraction.
ZOOMING  IN • Do the actin or myosin filaments change in length as contraction proceeds?
They do not change in length, they overlap more

19. Checkpoint 7-5: What are two properties of muscle cells that are needed for response to a stimulus?
Excitability and contractility
Checkpoint 7-6: What are the filaments that interact to produce muscle contraction?
Actin and myosin

20. The Role of Calcium Stored in endoplasmic reticulum (ER)
Is released when nerve fiber stimulates muscle cell
Attaches to proteins blocking receptor sites
Allows cross-bridges to form between actin and myosin
Returns to endoplasmic reticulum

21. Role of calcium in muscle contraction.

22. Energy Sources Muscle contraction requires energy (ATP)
Generated by oxidation of glucose or other usable nutrient
Compounds stored in muscle cells for energy production
Myoglobin
Stores reserves of oxygen
Glycogen
Storage form of glucose
Creatine phosphate
Stores energy

23. Checkpoint 7-7: What mineral is needed to allow actin and myosin to interact?
Calcium
Checkpoint 7-8: Muscle cells obtain energy for contraction from the oxidation of nutrients. What compound is formed in oxidation that supplies the energy for contraction?
ATP

24. Oxygen Consumption Aerobic metabolism Anaerobic metabolism
Requires oxygen
Used during normal activities
Anaerobic metabolism
Does not require oxygen
Used during strenuous activity
Less ATP produced
Lactic acid accumulates
Oxygen debt develops
Recovery oxygen consumption needed

25. Checkpoint 7-9: When muscles work without oxygen, a compound is produced that causes muscle fatigue. What is the name of this compound?
Lactic acid

26. Effects of Exercise Improved balance, joint flexibility
Increase in muscle size (hypertrophy)
Improvements in muscle tissue
Vasodilation
Strengthened heart muscle
Improved breathing and respiratory efficiency
Weight control
Stronger bones

27. Types of Muscle Contractions
Partial (muscle tone or tonus)
Isotonic
No change in tension
Muscle length shortens
Movement
Isometric
Great increase in tension
Muscle length unchanged
No movement

28. The Mechanics of Muscle Movement
Tendons attach muscles to bones
Origin—attached to more fixed part of skeleton
Insertion—attached to more moveable part of skeleton

29. Muscle attachments to bones.
ZOOMING  IN • Does contraction of the biceps brachii produce flexion or extension at the
elbow?
Flexion

30. Checkpoint 7-10: Muscles are attached to bones by means of tendons: one attached to a less movable part of the skeleton and one attached to a movable part. What are the names of these two attachment points?
The less movable part is the origin.
The more movable part is the insertion.

31. Muscles Work Together Many muscles function in pairs Prime movers
Produce given movement
Synergists
Assist prime movers
Antagonists
Oppose a given movement

32. Checkpoint 7-11: Muscles work together to produce movement
Checkpoint 7-11: Muscles work together to produce movement. What is the name of the muscle that produces a movement as compared with the muscle that produces an opposite movement?
The prime mover produces a movement and the antagonist produces the opposite movement

33. Levers and Body Mechanics
Musculoskeletal system as a lever system
Lever—bone
Fulcrum—joint
Force—applied by muscle
Three classes of levers
First class
Second class
Third class—most body movements

34. Levers

35. Checkpoint 7-12: Muscles and bones work together as lever systems
Checkpoint 7-12: Muscles and bones work together as lever systems. Of the three classes of levers, which one represents the action of most muscles?
Third class – the fulcrum is behind the point of effort and the weight

36. Skeletal Muscle Groups
Characteristics for naming muscles (often combined)
Location
Biceps brachii
Size
Gluteus maximus
Shape
Trapezoid
Direction of fibers
Transversus abdominus
Number of heads (attachment points)
Triceps brachii
Action
Extensor carpi ulnaris

37. Superficial muscles, anterior view

38. Superficial muscles, posterior view

39. Muscles of the Head Facial expression (orbicularis) muscles
Orbicularis oculi
Orbicularis oris
Levator palpebrae superioris
Buccinator
Mastication (chewing) muscles
Temporalis
Masseter
Tongue
Intrinsic
Extrinsic

40. Muscles of the head ZOOMING IN • Which of the
muscles in this illustration is
named for a bone it is near?
Frontalis, nasalis, mentalis and temporalis

41. Muscles of the Neck Are ribbonlike Extend up, down, or obliquely
Extend in several layers in a complex manner
Main one is sternocleidomastoid

42. Muscles of the Upper Extremities
Position the shoulder
Move the arm
Move the forearm and hand

43. Muscles That Move the Shoulder and Arm
Trapezius
Latissimus dorsi
Pectoralis major
Serratus anterior
Deltoid
Rotator cuff
Supraspinatus
Infraspinatus
Teres minor
Subscapularis

44. Muscles That Move the Forearm and Hand
Biceps brachii
Brachioradialis
Triceps brachii
Flexor carpi
Extensor carpi
Flexor digitorum
Extensor digitorum

45. Muscles that move the forearm and hand

46. Muscles of the Trunk Breathing muscles Abdominal muscles
Pelvic floor muscles
Deep back muscles

47. Muscles of Respiration
Diaphragm
Intercostal muscles

48. Muscles of respiration

49. Checkpoint 8-13: What muscle is most important in breathing?
The diaphragm

50. Muscles of the Abdomen and Pelvis
External oblique
Internal oblique
Transversus abdominis
Rectus abdominis
Levator ani

51. Muscles of the abdominal wall

52. Muscles of the female perineum (pelvic floor)

53. Checkpoint 7-14: What structural feature gives strength to the muscles of the abdominal wall?
The fibers of the muscles of the abdominal wall run in different directions.

54. Deep Muscles of the Back
Erector spinae
Deeper muscles in the lumbar area

55. Muscles of the Lower Extremities
Among the longest and strongest in the body
Specialized for locomotion and balance

56. Muscles That Move the Thigh and Leg
Gluteus maximus
Gluteus medius
Site of injection of many medications
Iliopsoas
Adductors
Sartorius
Hamstrings

57. Muscles of the thigh

58. Muscles That Move the Foot
Gastrocnemius
Achilles tendon
Soleus
Tibialis anterior
Peroneus longus
Flexor and extensor muscles

59. Muscles that move the foot

60. Effects of Aging on Muscles
Beginning at about age 40
Gradual loss of muscle cells
Loss of power
Tendency to flex hips and knees
Decrease in height