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Muscular System

Muscular System. Chapter 6. Functions of the Muscular System. Produces Movement-skeletal muscles are responsible for all locomotion and manipulation of the skeleton. Their speed and power help us stay safe.

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Muscular System

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  1. Muscular System Chapter 6

  2. Functions of the Muscular System • Produces Movement-skeletal muscles are responsible for all locomotion and manipulation of the skeleton. Their speed and power help us stay safe. • Maintaining Posture- muscle functions almost continuously as we sit or stand making tiny adjustments to help us overcome gravity • Stabilizing Joints-muscle reinforces and stabilizes joints • Generate Heat- by product of muscle activity is producing heat. Helps maintain normal body temperature

  3. 3 types of muscle • Skeletal- attached to bones or skin, appear to be long and cylindrical, multinucleated with obvious striations, voluntary, speed of contraction varies, no rhythmic contractions, controlled by nervous system. • Cardiac- makes up muscle of the heart, uninucleate, has striated appearance, involuntary, serves as a pacemaker so also controlled by nervous system, slow rhythmic contractions • Smooth- mostly makes up walls of organs, uninucleate, no striations, involuntary, nervous system controls, contractions are very slow and some are rhythmic.

  4. Microscopic Anatomy of Skeletal Muscle • See notes on page 1. The picture you see will be on the test and can be found on p. 164 also see p. 167 for diagrams. • Matching section will expect you to know • Actin- thin filaments • Myosin- thick filament, studded with myosin heads • A Band- bands where both actin and myosin are found • H Zone- lighter central portion of the A band • I band- contains only actin filaments • Z discs- actin filament anchored to disclike membranes • Sarcomere- tiny contractile unit that shortens during muscle contraction

  5. Types of Graded Responses • Twitch: single, brief contraction, not a normal muscle function. • Tetanus-summing of contractions, one contraction immediately followed by another, muscle doesn’t completely return to resting state, effects are added • Unfused (incomplete) Tetanus-some relaxation occurs between contractions • Fused (Complete) Tetanus- no evidence of relaxation following contractions.

  6. Energy for muscle contraction (ATP) • ATP is the only source of energy to power muscle. There is only enough for 4-6 seconds worth of energy. • There are 3 pathways to get more ATP • Direct phosphorylaton- ADP reacts with creatine phosphate (CP). Energy source is CP. 1 ATP per CP is created and will give 15 seconds of energy. • Anaerobic: (glycolysis and lactic acid formation) Energy comes from glucose, 2 ATP per glucose produces, 30-60 seconds of energy. • Aerobic: 95% of ATP created this way. Occurs in mitochondria, uses oxygen. Glucose is broken down and energy is released, creates 36 ATP per glucose, gives hours of energy.

  7. Muscle Fatigue • Unable to contract even though the muscle is being stimulated. If no rest, muscle will continue to contract weakly and finally stops contracting. • Due to Oxygen debt • Oxygen must be repaid to tissue to remove oxygen deficit. • Oxygen is required to get rid of accumulated lactic acid. • Increasing acidity and lack of ATP causes the muscles to contract less.

  8. Types of Muscle Contractions: • Isotonic Contractions: myofiliaments are able to slide past each other during contractions, muscle shortens and movement occurs. • Isometric contractions “Tension in muscle increases, the muscle is unable to shorten or produce movement.

  9. Muscle Tone • The state of partial contractions. The contraction is not visible but the muscle remains firm, healthy and constantly ready for action. • Different fibers contract at different times • The process of stimulating various fibers is under invlountary control. • People who have had injury can lose muscle tone. If paralyzed, muscle become flaccid or soft and flabby and begins to waste away

  10. Exercise and Muscle (use it or lose it) • Aerobic Exercise: endurance exercise (biking, jogging) results in stronger more flexible muscles with greater resistance to fatigue, makes body metabolism more efficient, improves digestion and coordination • Resistance Exercise: isometric exercise (weight lifting), increases muscle size and strength • Best to include both types of exercise in your routine.

  11. 5 Golden Rules for Skeletal Muscle Activity • All muscles cross at least one joint • Typically, the bulk of the muscle lies proximal to the joint crossed. • All muscles have at least two attachments: The origin and the insertion • Muscles can only pull, they never push • During contraction, the muscle insertion moves toward the origin.

  12. Muscles and Body Movements • Movement is attained due to a muscle moving an attached bone. • Muscles are attached to at least two points • Origin: attachment to a moveable bone • Insertion: attachment to an immovable bone

  13. Ordinary Body Movements • Flexion: decreases the angle of the joint, brings 2 bones closer together, typical of hinge joints like knee and elbow • Extension: opposite of flexion, increases angle between 2 bones. • Rotation: movement of a bone around its longitudinal axis, common in ball and socket joints; ex. Shaking your head no.

  14. Ordinary Body Movements • Abduction: movement of a limb away from the midline. • Adduction: opposite of abduction; movement of a limb toward the midline • Circumduction: combination of flexion, extension, abduction and adduction; common in ball and socket joints.

  15. Special Movements • Dorsiflexion-lifting the foot so that the superior surface approaches the shin. • Plantar flexion- depressing the foot(point thetoes) • Inversion-turn the sole of foot medially • Eversion- turn sole of foot laterally • Supination- forearm rotates laterally so palm faces anteriorly • Pronation- forearm rotates medially so palm faces posteriorly • Opposition- move thumb to touch the tips of other fingers on the same hand

  16. Types of Muscles • Prime mover- muscles with the major responsibility for a certain movement • Antagonist- muscles that opposes or reverses a prime mover • Synergist- muscle that aids a prime mover in a movement and helps prevent rotation • Fixator- stabilizes the origin of a prime mover

  17. Naming of Skeletal Muscles • By direction of muscle fibers. Ex. Rectus(straight) • By relative size of the muscle. Ex. Maximus (largest) • By location of the muscle. Ex. Temporalis (temporal bone) • By number of origins. Ex. Triceps (three heads) • By location of the muscle’s origin and insertion. Ex. Sterno(on the sternum) • By shape of the muscle. Ex. Deltoid(triangular) • By action of the muscle. Ex. Flexor and extensor

  18. Muscles of Head and Neck • Facial muscles • Frontalis – raises eyebrows • Orbicularisoculi- closes eyes, squintes, blinks, winks • Orbicularisoris – closes mouth and protrudes the lips • Buccinator- flattens the cheeks, chews • Zygomaticus- raises corners of the mouth Chewing Muscles: Masseter- closes the jaw and elevates the mandible Temporalis- synergist of the masseter, closes jaw

  19. Head and Neck Muscles • Platysma- pulls the corners of the mouth inferiorly • Sternocleidomastoid – flexes the neck, rotates the head

  20. Head and Neck Muscles

  21. Muscles of Trunk, Shoulder, Arm • Anterior Muscles • Pectoralis major- adducts and flexes the humerus • Intercostal Muscles • External intercostals- raise rib cage during inhalation • Internal intercostals- depress the rib cage to move air out of the lungs when you exhale forcibly

  22. Arm and Shoulder Muscles

  23. Muscles of the Abdominal Girdle • Rectus abdominis – flexes vertebral column and compresses abdominal contents (defecation, childbirth, forced breathing) • External and internal obliques- flex vertebral column, rotate trunk and bend it laterally • Transversusabdominis- compresses abdominal contents

  24. Posterior Muscles • Trapezius –elevates, depresses, adducts, and stabilizes the scapula • Latissimusdorsi- extends and adducts the humerus • Erector spinae- back extension • Quadratuslumborum- flexes the spine laterally • Deltoid – arm abduction

  25. Muscles of Upper Limb • Biceps Brachii- supinates forearm, flexes elbow • Brachialis- elbow flexion • Brachioradialis- weak muscle • Triceps Brachii- elbow extension (antagonist to biceps brachii)

  26. Muscles of lower limb • Gluteus maximus- hip extension • Gluteus medius- hip abduction, steadies pelvis when walking • Iliopsoas- hip flexion, keeps the upper body from falling backward when standing erect • Adductor muscles- adduct the thighs

  27. Muscles of the lower limb • Muscles causing movement at the knee joint • Hamstring group- thigh extension and knee flexion • Biceps femoris • Semimembranosus • semitendinosus

  28. Hamstring group

  29. Muscles of Lower limb • Muscles causing movement at the knee joint • Sartorius- flexes the thigh • Quadriceps group- extends the knee • Rectus femoris • Vastus muscles (3)

  30. Muscles of the Lower Limb • Tibialis anterior- dorsiflexion and foot inversion • Extensor digitorumlongus- toe extension and dorsiflexion of the foot • Fibularis muscles- plantar flexion, everts the foot • Soleus- plantar flexion

  31. Muscles of Lower Leg

  32. Anterior Muscles of the Body

  33. Posterior Muscles of the Body

  34. Intramuscular Injection Sites

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