VC Lesson2 Muscular System


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The lesson discusses about the muscles in the body.

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VC Lesson2 Muscular System

  1. 1. PowerPoint Presentation is made by ARLENE G.SALUSTIANO through compilation of different internetsources.The right of ownership is reserved to the maker of thepresentation.This can not be used without permission from the owner.For teaching use only and limited for school use.The owner respects the copyright ownership of theinternet sources herein; hence it cannot be published foruse outside.
  2. 2. The muscular system The muscular system makes up nearly half the weight of the human body, this is why when we train we sometimes put on weight instead of losing it. We put on muscle weight. The muscles provide the forces that enable the body to move.
  3. 3. WHAT DOES THIS SYSTEM DO?The big purpose of the musclesfound in your body is movement. Wecould be talking about the movementof your legs while you walk. We couldbe talking about the beating of yourheart. We could also be talking aboutthe contraction of a very small bloodvessel in your brain.
  4. 4. MUSCLES HELP YOU MOVEThe main parts of your voluntarymuscular system include themuscles, and tendons. The muscleis called the meatus. The bicep isthe meat that connect to the bonesso that you can move. Tendonsconnect your muscles to your boneat insertion points.
  5. 5. You have no control over most of themuscular system. You do control thevoluntary muscle in your arms, legs,neck, and torso. You have little or nocontrol over the heart or smoothmuscle. Those other muscles are underthe control of the autonomic nervoussystem (ANS).
  6. 6. INTERACTING WITH OTHER SYSTEMSThe muscular system is closelyconnected to the nervous system.You usually have to think beforeyou can move. Even thoughthinking is not always involved, theneurons of the nervous system areconnected to most of the cells inyour muscular system.
  7. 7. Muscles stretch across joints to linkone bone with another and work ingroups to respond to nerveimpulses.There are three types of muscle:
  8. 8. Muscle StructureOur muscle structure consistsof densely packed groups ofelongated cells known as musclefibres.Skeletal muscle is composed ofbundles of long striated fibres.
  9. 9. Smooth muscle which isfound in the walls of internalorgans such as intestines ismade of short spindle-shapedfibres packed together inlayers.Cardiac muscle found only inthe heart has shortinterconnecting fibres.
  10. 10. Skeletal muscleThere are nearly 650 skeletalmuscles in the human body! Skeletalmuscles are attached to theskeleton. They work in pairs: onemuscle moves the bone in onedirection and the other moves itback again.
  11. 11. Skeletal muscles are voluntarymuscles - in other words we thinkabout what movements we want tomake (at least, usually!) and sendmessages via our nervous system totell the appropriate muscle(s) tocontract.Muscle contractions can be short,single contractions or longer ones.
  12. 12. Skeletal muscle carries outvoluntary movements, and is whatwe use for movement in daily lifeand during exercise. The humanbody has more than 650 muscles, thebodys most abundant tissue,comprising about 23% of a womansbody weight and about 40% of amans body weight.
  13. 13. Smooth muscleSmooth muscle is found inour internal organs: in our digestivesystem, our blood vessels, ourbladder, our respiratory organs and,in a female, the uterus.Smooth muscle can stretch andmaintain tension over extendedperiods.
  14. 14. These fibres are held togetherby fibrous connective tissue.Capillaries penetrate this tissueto keep the muscles suppliedwith oxygen and nutrients thatare needed to fuel contraction.
  15. 15. In a relaxed muscle the thick andthin threads within a muscle fibreoverlap a little.When a muscle contracts, thethick filaments slide further inbetween the thin filaments likeinterlacing fingers. This actionshortens the entire fibre.
  16. 16. Cardiac muscleCardiac muscle is found only in theheart. It can stretch, just like smoothmuscle, and contract like skeletalmuscle.It is a twitch muscle - it only does shortsingle contractions.Like smooth muscle, cardiac muscleis involuntary.
  17. 17. Smooth muscles areinvoluntary muscles - in otherwords we do not have to thinkabout contracting thembecause they are controlledautomatically by the nervoussystem.
  18. 18. Smooth muscle surrounds or is partof the internal organs. Smoothmuscle is found in the digestivesystem, blood vessels, bladder,airways and, in a female, theuterus. It has the ability to stretchand maintain tension for longperiods of time. Both cardiac andsmooth muscles are calledinvoluntary muscles, because theycannot be consciously controlled.
  19. 19. You have smooth muscles that lineyour digestive system and helpmove food through your intestines.Smooth muscle also surroundsyour circulatory system and lymphsystem. Those muscle tissues arespread throughout your body andare even involved in controlling thetemperature of your body.
  20. 20. The stomach is an organ of thealimentary canal, a musculartube that forms part ofthe digestive system.The wall of the stomachcontains smooth muscletissue.
  21. 21. Contractions of the smoothmuscles of the alimentary canalserve to mix food with digestivejuices, and to move the resultingmixture further along(peristalsis). Smooth muscles arecalled involuntary muscles, becausethey cannot be consciouslycontrolled.
  22. 22. Skeletal muscles can do a short, singlecontraction (twitch) or a long,sustained contraction (tetanus), andmight ache after strenuous exercise. Askeletal muscle is composed of skeletalmuscle tissue, nervous tissue, blood,and connective tissues. Fascia coversthe surface of the muscle and alsoforms the cordlike tendons whichattach the muscle to the bone.
  23. 23. Epimysium lies beneath the fascia,and perimysium extends into thestructure of the muscle, where itseparates muscle tissue into smallcompartments of bundles of skeletalmuscle fibers called fascicles.Endomysium separates individualmuscle fibers within those fascicles.
  24. 24. Anatomy of Skeletal Muscle
  25. 25. According to the sliding filamenttheory, myosin cross-bridgesattach to a binding site on theactin filament and bend slightly,thus pulling on the actin filament.The filaments slide past oneanother, thus shortening thesarcomeres, thus shortening themyofibrils, thus shortening themuscle fiber.
  26. 26. Then the head of the myosincross-bridge can release,straighten, combine withanother binding site furtherdown the actin filament, andpull again, thus shortening thesarcomere, (myofibril andmuscle fiber) more.
  27. 27. The actions of the myosin molecules arenot synchronized - at any given moment,some myosins are attaching to the actinfilament, others are creating force(pulling) and others are releasing theactin filament).This process can be repeated for as longas the muscle fiber is stimulated, or untilthe point of maximal shortening of thesarcomere.
  28. 28. When the muscle fiber is no longerstimulated, the cross-bridges breakdown, and the muscle fiber relaxes.
  29. 29. Blood vessels and axons of nervecells lie within those connectivetissues. A skeletal muscle fiber is asingle, thin, long cell that mayextend the full length of themuscle. Just beneath its cellmembrane (sarcolemma), thecytoplasm (sarcoplasm) of the fibercontains many threadlikemyofibrils that lie parallel to oneanother.
  30. 30. Each myofibril consists of repeatingunits called sarcomeres. Thecharacteristic dark and lightstriations of a sarcomere are due tothe arrangement of two kindsof protein filaments: thick filamentscomposed of the protein myosin andthin ones mainly composed of theprotein actin.
  31. 31. •The contraction of a muscle does notnecessarily mean that the muscleshortens; it only means that tension hasbeen generated. When muscles docause a limb to move through thejoints range of motion, they usually actin the following cooperating groups:Agonists cause the movement tooccur. They create the normal rangeof movement in a joint by contracting.
  32. 32. •Agonists are also referred toas prime movers since they are themuscles that are primarilyresponsible for generating themovement.•Antagonists act in opposition tothe movement generated by theagonists and are responsible forreturning a limb to its initialposition.
  33. 33. •Synergists assist the agonist andmake its action more effective byhelping to hold the joint steady andkeeping the two bones around thejoint aligned. Synergists are alsosometimes called stabilizers.
  34. 34. Primary opposing muscle groups:1. calves/tibialis anterior,2. quadriceps/hamstrings,3. hip flexors/gluteals,4. erector spinae/abdominals,5. pectorals/upper back,6. latissimus dorsi/deltoids,7. biceps/triceps.
  35. 35. A skeletal muscle fiber is a single,thin, long cell that may extend thefull length of the muscle. Justbeneath its cell membrane(sarcolemma), the cytoplasm(sarcoplasm) of the fiber containsmany threadlike myofibrilsthat lie parallel to one another. Each myofibril consists of repeatingunits called sarcomeres.
  36. 36. The characteristic dark and lightstriations of a sarcomere are due to thearrangement of two kinds of proteinfilaments: thick filaments composed ofthe protein myosin and thin ones mainlycomposed of the protein actin. Amuscle fiber contraction is a complexinteraction of molecules, resulting in amovement within the myofibrils inwhich the myosin and actin filamentsslide past one another.
  37. 37. As the intensity of stimulationincreases, recruitment of motor unitscontinues until, finally, all possiblemotor units in that muscle areactivated and the muscle contractswith maximal tension.
  38. 38. A single stimulus of thresholdstrength activates some of a muscle’smotor units, which makes the musclecontract and then relax. This actionlasts only a fraction of a second and iscalled a twitch.
  39. 39. A whole muscle is composed ofmany motor units controlled bydifferent motor neurons, whichrespond to different thresholdsof stimulation. If only the motorneurons with low thresholds arestimulated, few motor unitscontract, and the musclecontracts with minimal tension.
  40. 40. At higher intensities ofstimulation, additional motorneurons respond, and moremotor units are activated, whichproduces a stronger musclecontraction. Such an increase inthe number of motor units beingactivated is called recruitment.
  41. 41. When the muscle is stretched, so isthe muscle spindle, which recordsthe change in length (and how fast)and sends signals to the spinewhich convey this information.
  42. 42. This triggers the stretch reflexwhich attempts to resist thechange in muscle length by causingthe stretched muscle to contract.The more sudden the change inmuscle length, the stronger themuscle contractions will be(plyometric, or "jump", training isbased on this fact).
  43. 43. This basic function of the musclespindle helps to maintain muscletone and to protect the body frominjury. However, ballistic stretchingmay cause a muscle contraction sostrong it tears the muscle fibers ortendons, causing injury.
  44. 44. One of the reasons for holding astretch for a prolonged period oftime (static stretching) is that as themuscle is held in a stretchedposition, the muscle spindlebecomes accustomed to the newlength and reduces itssignaling. Gradually, you can trainyour stretch receptors to allowgreater lengthening of the muscles.
  45. 45. Physiology of Skeletal MuscleA muscle fiber contracts only whenstimulated by its nerve, the motorneuron. A nerve impulse from themotor neuron translates into a muscleimpulse that affects the whole musclefiber at once, for as long as thestimulation continues. A stimulatedskeletal muscle fiber responds to itsfullest extend, i.e., it has an all-or-noneresponse.
  46. 46. While each muscle fiber isconnected to only one axon of amotor neuron, a motor neuronmay have many densely branchedaxons, connecting to manymuscle fibers, constitutinga motor unit.
  47. 47. When muscles contract (possiblydue to the stretch reflex), theyproduce tension at the point wherethe muscle is connected to thetendon, where the golgi tendonorgan is located. The Golgi tendonorgan records the change intension, and the rate of change ofthe tension, and sends signals tothe spine to convey thisinformation.
  48. 48. When this tension exceeds acertain threshold, it triggersthe lengthening reaction whichinhibits the muscles fromcontracting and causes them torelax.
  49. 49. Skeletal Muscle ActionAnother reason for holding astretch for a prolonged period oftime is to allow this lengtheningreaction to occur, thus helping thestretched muscles to relax. It iseasier and more beneficial tostretch, or lengthen, a muscle whenit is not trying to contract.
  50. 50. This basic function of the golgitendon organ helps to protect themuscles, tendons, and ligamentsfrom injury. The lengtheningreaction is possible only becausethe signaling of golgi tendon organto the spinal cord is powerfulenough to overcome the signalingof the muscle spindles telling themuscle to contract.
  51. 51. The response time betweenstimulation and muscle reactiondetermines the classificationinto fast twitch or slowtwitch fibers. Fast-twitch fibersare capable of developing greaterforces, contracting faster toproduce bursts of power and havegreater anaerobic capacity.
  52. 52. In contrast, slow-twitch fibersdevelop force slowly, canmaintain contractions longer,have greater endurance andhigher aerobic capacity.
  53. 53. The skeletal muscles of an averageperson contain about half fasttwitch and half slow twitch musclefibers. Certain athletic activitiespromote increased percentage offast twitch muscle fibers (Olympicsprinter), or slow twitch musclefibers (Olympic marathoner).
  54. 54. A muscle fiber exposed to a series ofstimuli of increasing frequencyreaches a point when it is unable tocompletely relax before the nextstimulus in the series arrives. Whenthis happens, the force of individualtwitches combines, a processcalled summation.
  55. 55. When the resulting forceful,sustained contraction lacks evenpartial relaxation, it is called atetanic contraction (tetanus).
  56. 56. As we have no control over thesmooth muscle tissue of thestomach, we cannot consciouslycontract it, or “exercise” it. Thus,there are no “exercises tostrengthen the stomach” or “usingthe stomach to move thespine”. The term "stomach"therefore does not belong intoPilates class.
  57. 57. A muscle fiber contraction is acomplex interaction of molecules,resulting in a movement within themyofibrils in which the myosin and actinfilaments slide past one another (slidingfilament theory).Along side (in parallel) with the regularmuscle fibers are muscle spindles orstretch receptors, the primaryproprioceptors in the muscle.
  58. 58. They undergo the same lengthchanges as the rest of the muscleand thus measure the change inmuscle length and the rate ofchange in muscle length. In thetendon of the muscle is locatedthe Golgi tendon organ. It issensitive to the change in tensionand the rate of change of thetension, i.e., force the muscleexerts.
  59. 59. Summation and recruitmenttogether can produce a sustainedcontraction of increasingstrength. Although twitches mayoccasionally occur in skeletalmuscles (e.g., eyelid twitch), suchcontractions are of limiteduse. More commonly muscularcontractions are sustained.
  60. 60. Even when a muscle appears to beat rest, a certain amount ofsustained contraction is occurringin a small fraction of the totalnumber of its fibers. This muscletone is important particularly inmaintaining posture, and alsoenables the muscle to resist passiveelongation or stretch.
  61. 61. They undergo the same lengthchanges as the rest of the muscleand thus measure the change inmuscle length and the rate ofchange in muscle length. In thetendon of the muscle is locatedthe Golgi tendon organ. It issensitive to the change in tensionand the rate of change of thetension, i.e., force the muscleexerts.
  62. 62. When the actin and myosin contractin the muscles, the muscle shortensand the bones are pulled closertogether.Muscles called flexors force yourjoints to bend.
  63. 63. Muscles called extensors causeyour limbs to straighten. A bicep isa flexor and the triceps areextensors. You may have alsoheard of ligaments. They arebatches of connective tissue thatbind bones to each other.Muscles, tendons, and ligamentscan been found working togetherin almost all of your joints.
  64. 64. Muscles for Mastication: • Masseter • Temporalis • Lateral Pterygoid • Medial Pterygoid
  65. 65. Muscles for Facial Expression:• Frontalis• Orbicularis oculi (planned)• Nasalis (planned)• Orbicularis oris (planned)• Levator labii superioris (planned)• Levator anguli oris (planned)• Zygomaticus major (planned)• Zygomaticus minor (planned)• Risorius (planned)• Depressor anguli oris (planned)• Depressor labii inferioris (planned)• Mentalis (planned)
  66. 66. Posterior Neck Muscles : • Splenius capiitis • Splenius cervicis • Semispinalis capiitis • Semispinalis cervicis • Semispinalis thoracis • Trapezius • Suboccipital musclesAnterior Neck Muscles :•Sternocleidomastoid• Scalenes
  67. 67. Erector Spinal Muscles : • Iliocostalis Thoracis • Iliocostalis Lumborum • Longissimus Capitis • Longissimus Cervicis • Longissimus Thoracis • Spinalis Cervicis • Spinalis ThoracisTransversospinal Muscles:• Multifidus• Rotators (planned)
  68. 68. Muscles That Act On Anterior Arm:• Deltoid (anterior & middle)• Pectoralis major• Biceps brachii• Coracobrachialis• Subscapularis• Teres major (from the back)• Latissimus dorsai (from the back)
  69. 69. Muscles That Act On Posterior Arm: • Deltoid (posterior and middle) • Supraspinatus • Infraspinatus • Teres minor • Triceps brachii: long head
  70. 70. Muscles That Act On AnteriorShoulder:• Serratus Anterior• Pectoralis Minor
  71. 71. Muscle That Act On Posterior Shoulder:• Levator Scapulae• Trapezius• Rhomboid Major• Rhomboid Minor
  72. 72. Muscles That Act On Anterior Forearm:• Biceps Brachii• Brachialis• Brachioradialis• Pronator teres
  73. 73. Muscles of the Abdomen: • External oblique • Internal oblique • Transversus abdominus • Rectus abdominusk
  74. 74. Muscle That Act On Posterior Forearm:• Triceps brachii: long head• Triceps brachii: medial head• Triceps brachii: lateral head• Anconeus
  75. 75. Muscles That Act On AnteriorWrist/Hand:• Flexor carpi radialis• Palmaris longus• Flexor carpi ulnaris• Flexor digitorum superficialis
  76. 76. Muscle That Act On Posterior Wrist/Hand:• Extensor carpi radialis longus• Extensor carpi radialis brevis• Extensor digitorum• Extensor carpi ulnaris
  77. 77. Muscles of the Legs (Front)• Iliacus• Psoas major• Tensor fasciae latae• Sartorius• Rectus femoris• Pectineus• Adductor longus• Adductor brevis• Adductor magnus• Gracilis
  78. 78. Muscles of the Legs (Back):• Gluteus maximus• Gluteus medius• Gluteus minimus• Piriformis• Quadratus femoris• Biceps femoris - long head• Semimembranosus• Semitendinosus
  79. 79. Muscles That Act On Anterior Leg: Rectus femoris• Sartorius• Gracilis• Vastus lateralis• Vastus medialis• Vastus intermedius
  80. 80. Muscle That Act On Posterior Leg:• Semimembranosus• Semitendinosus• Biceps femoris - long head• Biceps femoris - short head• Gastrocnemius• Plantaris• Popliteus
  81. 81. Anterior Leg Compartment Muscles:• Tibialis anterior• Extensor digitorum longus• Extensor hallucis longus• Fibularis (peroneus) tertius longus
  82. 82. Posterior Leg Compartment Muscles: • Gastrocneumius • Soleus • Plantaris • Flexor hallucis longus • Flexor digitorum longus • Tibialis anterior
  83. 83. Lateral Leg Compartment Muscles:• Fibularis (peroneus) longus• Fibularis (peroneus) brevis
  84. 84. Repetitive Strain InjurySeveral Conditions are referred to asrepetitive strain injury. These areconditions caused by the constantrepetition of a particular movement.Irritation of the flexor and extensortendons in the wrist and hand is acommon injury that often affectskeyboard operators causing painwhen the fingers are moved.
  85. 85. It is also a condition suffered bybody builders and weighttrainers who constantly put strainon the same muscles.The symptoms of RSI include pain,aching and tingling. Sometimesrestricted movement or weakness.RSI can also lead to anotherdisorder called carpal tunnelsyndrome.
  86. 86. This is due to pressure on themedian nerve as it passes through agap under a ligament at the frontof the wrist. This disorder ischaracterized by numbness andpain in the thumb and middlefingers. The condition is caused bypressure on the median nerve.
  87. 87. Prepare a dance demo for each groupwith the dance routine and music ofyour choice.This dance demo will be presented insidethe classroom on December 5, 2012.
  88. 88. http://www.human- body- system.html