P&A - Muscular system

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P&A - Muscular system

  1. 1. Muscular System
  2. 2. I. Muscle Types • A. Smooth – 1. S: muscle which LACKS STRIATIONS (stripes) and is located in stomach, intestines, bladder, uterus, and blood vessels • Arranged in layers – 2. It is INVOLUNTARY MUSCLE • Unconsciously contracts – 3. F: move food through digestive tract, constrict blood vessels, contract uterus, empty bladder
  3. 3. • B. Cardiac – 1. S: muscle which IS STRIATED located in the heart and contains INTERCALATED DISKS • Def of ID: junctions of cardiac muscle cells which transmit impulses easily and allow the heart to beat as one • Cells look as though they are in figure 8 patterns – 2. it is INVOLUNTARY muscle – 3. F: to pump blood into heart chambers and certain blood vessels
  4. 4. • C. Skeletal – 1. S: muscle found connected to bones which IS STRIATED • Contain much connective tissue to attach to bones – 2. they are VOLUNTARY • Can consciously control contractions – 3. F: to move head, neck, trunk, limbs, facial expressions, and many actions like writing, chewing, talking etc • ** throughout this unit we will focus on structure and function of SKELETAL muscle
  5. 5. II. Muscle Structure • A. Connective Tissue Coverings – 1. Fascia • Fibrous tissue covering of individual muscle – 2. Tendon • Extension of tissue connecting muscle to bone • Ex: Tendonitis – swelling of tendon at connection – 3. Epimysium • Under fascia – 4. Perimysium • Separate muscle into bundles – 5. Endomysium • Surrounds individual muscle fiber/cell
  6. 6. • B. Skeletal Muscle Fibers – 1. 1 fiber = 1 cell – 2. sarcolemma – cell membrane – 3. sarcoplasm – cytoplasm in cell – 4. myofibrils – parallel fibers in sarcoplasm • a. myosin – T H I C K , DA R K protein filament • b. actin – Thin,lightprotein filament • ** actin and myosin make striations in muscle – light/dark
  7. 7. – 5. A-bands • Dark portion of muscle myofibril – 6. I-bands • Light portion of muscle myofibril – 7. Z-lines • Place where actin myobifrils meet – 8. Sarcoplasmic reticulum • Channels running parellel on outside of fiber – 9. Transverse Tubules – T Tubules • Channels running opposite SR between SR on outside of fiber – ** SR and T Tubules communicate signal to whole muscle when stimulated
  8. 8. • C. Skeletal Muscle Contraction – 1. Neuromuscular Junction • Def – connection between nerve fiber and muscle • ** Each muscle is connected to a nerve called a motor neuron – 2. Role of myosin and actin • Myosin cross bridges connect to actin and pull
  9. 9. – 3. Process of Contraction • a. motor neuron releases ACETYLCHOLINE – Chemical needed for a muscle contraction • b. actetylcholine stimulates impulses through the SR and T Tubules • c. impulses cause Ca+ to move through the muscle • d. Myosin cross bridges connect to actin myofibrils because of presence of Ca+ • e. bridges slide actin along myosin = CONTRACTION • f. Ca+ leave muscle • g. Myosin releases bridges = MUSCLE RELAXES
  10. 10. • D. O2 Debt, Fatigue, and Heat Production – 1. O2 Debt • a. if muscles are exercised strenuously, O2 cannot be supplied fast enough • b. Lactic Acid builds up • c. ATP energy (body’s energy) decreases • d. CO2 increases • e.O2 must be replenished before more exercise can be done – may take hours – ** the O2 needed to replenish is O2 debt • f. to replenish O2 you automatically breath deep and fast
  11. 11. – 2. Muscle fatigue • a. def – MF occurs when a muscle loses its ability to contract • b. causes: – Blood supply is cut off (no O2) – Acetylcholine supply runs out in motor neuron – Build up in lactic acid • c. cramping results – Muscle keeps contracting and can’t relax
  12. 12. – 3 . Heat Production – Muscle contractions release heat – Keeps body at 98.6
  13. 13. • E. Muscle responses – 1. Threshold Stimulus • a. def – the minimum stimulus strength needed to cause a muscle contraction • ** electric stim on muscles uses this on isolated muscles to help strengthen them – 2. ALL or NONE response • a. there are NO partial contractions in muscle FIBERS • b.Once stimulus is reached, muscle fiber contracts to full extent • C.Not all muscle fibers are stimulated – weaker contraction
  14. 14. – 3. Contraction types • a. twitch – a single contraction that lasts only a fraction of a second • b. tetany – a sustained forceful contraction which lacks relaxation – Ex: holding a heavy box still out on front of your body • c. tonus – a small sustained contraction in a muscle which seems to be at rest – Due to the muscle being contracted rapidly for varying lengths of time – Ex: when walking and leg is back – Ex: maintaining posture
  15. 15. • F. Muscle Interactions – 1. origin • Def: immovable place where muscle is attached – 2. insertion • Def: moveable place where muscle is attached • ** insertion always moves towards origin – Ex: Bicep Brachii • Origin: coracoid process and scapula • Insertion: radius
  16. 16. – 3. Muscles ALWAYS act in groups • a. prime mover – The muscle responsible for the most movement – Ex: lift arm = deltoid • b. synergists – Muscles the contract and ASSIST prime mover – Helpers • c. antagonist – Muscle that acts against the prime mover – Ex: flex arm » PM – bicep brachii - contracts » Ant – tricep - extends
  17. 17. – 4. muscle fiber types • a. fast twitch – Muscles which contract quickly and tire quickly – Ex: sprinters • b. slow twitch – Muscles which contract slow and are more resistant to fatigue – Ex: marathon runners, weight lifters
  18. 18. III. Major Skeletal Muscles • A. Muscles of Facial Expression – 1. frontalis • Lies over frontal bone – 2. occipitalis • Lies over occipital bone – 3. orbicularis oculi • Around the eye orbit – 4. orbicularis oris • Around mouth orbit
  19. 19. – 5. buccinator • Fish face – 6. zygomaticus • Smiling – 7. platysma
  20. 20. • B. Muscles of chewing – mastication – 1. masseter • Main muscle of chewing – 2. temporalis • Lies over temporal bone
  21. 21. • C. Muscles that move the head – 1. sternocleidomastoid • Head flexion – 2. splenis capitis – 2. semispinalis capitis
  22. 22. • D. Muscles of the pectoral girdle – 1. trapezius • O: – Occipital bone – Spinous process of cervical and thoracic vertebrae • I: – Clavicle – Scapula • A: – Move scapula – Raise arm
  23. 23. – 2. Rhomboideus Major – 3. serratus anterior – 4. pectoralis minor • O: – Sternal ends of upper ribs • I: – Coracoid process • A: – Pull scapula down – Pull scapula forward – Raise ribs
  24. 24. • E. Muscles that move the Upper Arm – 1. Pectoralis Major • O: – clavicle – Sternum – Costal cartilage • I: – Humerous • A: – Adduct arm – Rotate humerus – Pull arm forward
  25. 25. – 2. Teres Major – 3. Latissimus Dorsi • O: – Spinous process of vertebrae – Iliac crest – Lower ribs • I: – Humerous • A: – Adducts arm – Pulls shoulder down and back
  26. 26. – 4. supraspinatus – 5. deltoid • O: – Acromion process – Scapula spine – Clavicle • I: – Humerous • A: – Abducts arm – main muscle to abduct
  27. 27. – 6. subscapularis • On anterior side of scapula – 7. infraspinatus – 8. teres minor
  28. 28. • F. Muscles that move the forearm – 1. biceps brachii • O: – Coracoid process – Scapula • I: – Radius • A: – Flex arm at elbow – Rotate hand laterally
  29. 29. – 2. Brachialis – 3. brachioradialis – 4. triceps brachii • O: – Lateral and medial surfaces of humerous • I: – Proximal ulna • A: – Extend arm at elbow
  30. 30. – 5. supinator • In charge of supination – 6. pronator teres – 7. pronator quadratus
  31. 31. • G. Muscle that move the wrist, hand, and fingers – 1. flexor carpi radialis – 2. flexor carpi ulnaris – 3. extensor carpi radialis longus – 4. extensor carpi radialis brevis – 5. extensor carpi ulnaris – 6. extensor digitorum
  32. 32. • H. Muscles of the abdomen – 1. LINEA ALBA • CONNECTIVE TISSUE which abdominal muscles connect to – 2. external oblique • O: – Outer surface of lower rib • I: – Linea alba, iliac crest • A: – Compress abdomen
  33. 33. – 3. internal oblique • O: – Iliac crest • I: – Rib cartilage, linea alba, pubis • A: – Compress abdomen – 4. Transverse abdominus
  34. 34. – 5. Rectus abdominus • O: – Pubis • I: – Xyphoid process, costal cartilage • A: – Compress abdomen, flex vertebral column
  35. 35. • I. Muscles that move the Thigh – 1. tensor fascia latae – 2. gluteus maximus • O: – Sacrum, coccyx, ilium • I: – Posterior femur • A: – Extend leg at hip
  36. 36. – 3. gluteus medius • Top of maximus over hip – 4. adductor longus – 5. adductor magnus – 6. gracilis – 7. fascia: sheet of connective tissue which muscle may connect to
  37. 37. • J. Muscles that move the lower leg – ** the next 3 muscles make up the HAMSTRING – 1. biceps femoris • O: – Ischium and posterior surface of femur • I: – Fibula, tibia • A: – Flex/rotate leg, extend thigh
  38. 38. – 2. semitendinosous – 3. semimembranous
  39. 39. – 4. sartorius • Longest muscle in body • Crosses 2 joints – 5. quadraceps femoris • Rectus femoris • Vastus lateralis • Vastus medialis • Vastus intermedius
  40. 40. • K. Muscles that move ankle, foot, and toes – 1. tibialis anterior • O: – Lateral surface of tibia • I: – Tarsals, 1st metatarsal • A: – Dorsal flexion and inversion of foot
  41. 41. – 2. extensor digitorum longus • Extends toes -digits – 3. gastrochnemius • O: – Lateral/medial condyles of femur • I: – Posterior surface of calcaneous • A: – Plantar flexion of foot and flexion of leg at knee – 4. soleus – 5. flexor digitorum longus – 6. peroneous longus

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