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The Muscular System

Chapter 9. The Muscular System. Introduction. Skeletal muscles: movement in environment Smooth muscles: intestines, ureters, veins and arteries Cardiac muscle: pumps blood through heart and blood vessels 40% - 50% of body weight. The Types of Muscle. The Types of Muscle (cont’d.).

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The Muscular System

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  1. Chapter 9 The Muscular System

  2. Introduction • Skeletal muscles: movement in environment • Smooth muscles: intestines, ureters, veins and arteries • Cardiac muscle: pumps blood through heart and blood vessels • 40% - 50% of body weight

  3. The Types of Muscle

  4. The Types of Muscle (cont’d.) • Skeletal: voluntary, striated, multinucleated • Smooth: involuntary, nonstriated and uninucleated • Cardiac: involuntary, striated and uninucleated

  5. The Anatomy of Skeletal or Striated Muscle

  6. The Anatomy of Skeletal or Striated Muscle (cont’d.) • Skeletal muscle cell surrounded by sarcolemma • Fasciculi: bundles of fascicles • Fascicles: individual bundles of muscle fibers • Perimysium: surrounds each fascicle

  7. The Anatomy of Skeletal or Striated Muscle (cont’d.) • Epimysium: covers the perimysium • Fascia: covers the epimysium • Myosin: A bands • Actin: I bands • Z lines • H zone

  8. The Anatomy of Skeletal or Striated Muscle (cont’d.) • Sarcomere: between two adjacent Z lines • Actual contraction process occurs here • Sarcotubular system • T system and sarcoplasmic reticulum

  9. The Physiology of Muscle Contraction

  10. Introduction • Motor unit: all muscle cells innervated by one motor neuron • Muscle cell properties • Excitability • Conductivity • Contractility • Elasticity

  11. Neuroelectrical Factors • Na+ higher concentration outside muscle cell • K+ higher concentration inside muscle cell • Resting potential: charge outside positive and inside negative • Electrical potential: rush of Na+ inside cell • K+ moves outside cell attempting to balance

  12. Neuroelectrical Factors (cont’d.) • Action potential • Calcium released • Troponin and tropomyosin action inhibited • Activated myosin links to actin filaments

  13. Chemical Interactions • Myosin heads contain ATP • ATP releases energy upon myosin/action link • Energy released used to pull action • Sodium: potassium pump pumps out sodium • Resting potential restored

  14. Energy Sources • ATP: energy source for muscle contraction • ATP production • Glycolysis • Krebs citric acid cycle • Electron transport • Alternate sources: fatty acids and phosphocreatine

  15. The Muscle Twitch

  16. The Muscle Twitch (cont’d.) • Stimulus > latent period > contraction > relaxation • Contraction strength depends on • Strength, speed and duration of stimulus • Weight of load • Temperature • All-or-none law

  17. Muscle Tone

  18. Muscle Tone (cont’d.) • State of partial contraction throughout whole muscle • Maintains pressure on abdominal contents • Helps maintain blood pressure • Aids digestion • Types • Isotonic, isometric

  19. The Anatomy of Smooth Muscle

  20. The Anatomy of Smooth Muscle (cont’d.) • Found in hollow structures • Involuntary, uninucleated, nonstriated • Arrangement (two layers) • Longitudinal (outer) • Circular (inner)

  21. The Anatomy of Cardiac Muscle

  22. The Anatomy of Cardiac Muscle (cont’d.) • Autonomic nervous system control • Involuntary, uninucleated, striated • Intercalated disks: coordinate contraction • Cardiac muscles: contract, relax and contract 75 times/minute

  23. The Naming and Actions of Skeletal Muscles

  24. The Naming and Actions of Skeletal Muscles (cont’d.) • Action • Shape • Origin and insertion • Location • Direction of fibers

  25. The Naming and Actions of Skeletal Muscles (cont’d.) • Origin: more fixed attachment of muscle • Insertion: movable attachment of muscle • Tendons: attach muscle to bone • Aponeurosis: wide flat tendon

  26. The Naming and Actions of Skeletal Muscles (cont’d.) • Flexors: bend limb at a joint • Extensor: straighten limb at a joint • Abductors: move limb away from midline • Adductors: bring limb toward midline • Rotators: revolve limb around axis

  27. The Naming and Actions of Skeletal Muscles (cont’d.) • Dorsiflexors: raise the foot • Plantar flexors: lower the foot • Supinators: turn palm upward • Pronators: turn palm downward

  28. The Naming and Actions of Skeletal Muscles (cont’d.) • Levators: raise a part of the body • Depressors: lower a part of the body • Prime movers or agonists: bring about an action • Antagonists: oppose agonists • Synergists: assist prime movers

  29. The Function and Location of Selected Skeletal Muscles

  30. Superficial Muscles • Superficial muscles of the body, anterior view

  31. Superficial Muscles (cont’d.) • Superficial muscles of the body, posterior view

  32. Muscles of Facial Expression • Occipitalis • Frontalis • Zygomaticus • Levator labii superioris • Orbicularis oris and buccinator

  33. Muscles of Facial Expression (cont’d.) • Muscles of the head and neck, anterior view

  34. Muscles of Facial Expression (cont’d.) • Muscles of the head and neck, lateral view

  35. Muscles of Mastication • Masseter • Temporalis • Pterygoid

  36. Muscles of the Eye • Superior rectus • Inferior rectus • Medial rectus • Lateral rectus • Superior and inferior oblique

  37. Muscles Moving the Head • Sternocleidomastoid • Contraction of both causes flexion of neck • Contraction of one causes rotation to left or right

  38. Muscles Moving the Shoulder Girdle • Levator scapulae • Rhomboids • Pectoralis minor • Trapezius • Serratus anterior

  39. Muscles Moving the Humerus • Pectoralis major • Latissimus dorsi • Teres minor • Deltoid • Supraspinatus • Infraspinatus

  40. Muscles Moving the Elbow • Brachialis • Biceps brachii • Brachioradialis • Triceps brachii • Anconeus

  41. Muscles Moving the Wrist • Flexor carpi • Extensor carpi

  42. Muscles Moving the Hand • Supinator • Pronator teres • Pronator quadratus

  43. Muscles Moving the Thumb • Flexor pollicis • Extensor pollicis • Adductor pollicis • Abductor pollicis • Opponens pollicis

  44. Muscles Moving the Fingers • Flexor digitorum • Extensor digitorum • Interossei

  45. Muscles of the Abdominal Wall • External oblique • Internal oblique • Transversus abdominis • Rectus abdominis

  46. Muscles of the Abdominal Wall (cont’d.)

  47. Muscles of Respiration or Breathing • Diaphragm • Main muscle • External and internal intercostals • Expand the ribs

  48. Muscles Moving the Femur • Psoas • Iliacus • Gluteus maximus • Gluteus medius • Gluteus minimus • Tensor fascia lata

  49. Muscles Moving the Knee Joint • Biceps femoris • Semitendinosus • Semimembranosus • Popliteus • Gracilis • Sartorius • Quadriceps femoris

  50. Muscles Moving the Foot • Gastrocnemius • Tibialis posterior • Soleus • Peroneus longus • Plantaris • Tibialis anterior • Peroneus tertius

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