Skeletal Muscle Tissue And Organization

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Skeletal Muscle Tissue And Organization

  1. 1. <ul><li>Describe the distinguishing characteristics of the different muscle tissues </li></ul><ul><li>Discuss the organization of skeletal muscle </li></ul><ul><li>Explain the micro-anatomy of a skeletal muscle fiber </li></ul><ul><li>Describe the fascicle arrangement in different types of muscle </li></ul><ul><li>Review general muscle terminology </li></ul>Skeletal Muscle Tissue and Organization main objectives: www.freelivedoctor.com
  2. 2. Muscle tissue vs. Muscle as an organ <ul><li>One of the 4 primary tissue types </li></ul><ul><li>How many subtypes? </li></ul><ul><li>Made up of _____ tissue types. </li></ul><ul><li>> 700 skeletal muscles </li></ul><ul><li>Word roots: </li></ul><ul><ul><li>sarco </li></ul></ul><ul><ul><li>mys </li></ul></ul>www.freelivedoctor.com
  3. 3. Function of Skeletal Muscles <ul><li>Skeletal movement </li></ul><ul><li>Posture and body position </li></ul><ul><li>Support of soft tissues </li></ul><ul><li>Guarding of entrances & exits </li></ul><ul><li>Maintenance of body temperature </li></ul>www.freelivedoctor.com
  4. 4. Gross Anatomy Each skeletal muscle is wrapped by 3 concentric layers of connective tissue. www.freelivedoctor.com
  5. 5. Epi-, Peri-, and Endomysium <ul><li>Are interwoven - Go over into tendon </li></ul><ul><li>Distinguish between: </li></ul><ul><ul><li>Tendon </li></ul></ul><ul><ul><li>Aponeurosis </li></ul></ul><ul><ul><li>Ligament </li></ul></ul><ul><li>Function: </li></ul><ul><ul><li>Protection </li></ul></ul><ul><ul><li>Blood supply </li></ul></ul><ul><ul><li>Innervation </li></ul></ul>www.freelivedoctor.com
  6. 6. Nerve and Blood Vessel Supply <ul><li>Skeletal muscles are rich in nerves and blood vessels </li></ul><ul><li>Chemical communication at Synapsis (neuromuscular junction) </li></ul><ul><li>Synaptic terminal of axon meets motor end plate of muscle cell </li></ul><ul><li>Coiled capillaries are able to adapt to changes in length of muscle fiber </li></ul>www.freelivedoctor.com
  7. 7. Microanatomy of Skeletal Muscle Fibers <ul><li>Some vocabulary: </li></ul><ul><li>Skeletal muscle fiber or myofiber </li></ul><ul><li>Sarcolemma </li></ul><ul><li>Sarcoplasm </li></ul><ul><li>Sarcoplasmic reticulum </li></ul><ul><li>Myofibril </li></ul><ul><li>Myofilaments </li></ul>Fig 9-3 www.freelivedoctor.com
  8. 8. Myofiber (  100µm) Myofibrils (  1-2 µm) Myofilaments Actin & Myosin Myofilaments www.freelivedoctor.com
  9. 9. Sarcomeres <ul><li>Thick and Thin Filaments are organized in repeating functional units = ______ </li></ul><ul><li>Each myofibril has linear arrangement of ~ 10,000 sarcomers </li></ul><ul><li>Banded appearance (striation) due to arrangement of thick and thin filaments </li></ul><ul><li>Interaction of thick and thin filaments responsible for skeletal muscle fiber contraction </li></ul>www.freelivedoctor.com
  10. 10. Sarcomere Structure Z - line A- band = dArk band I - band = LIght band www.freelivedoctor.com
  11. 11. Thin Filament: Actin F-actin G-actin www.freelivedoctor.com
  12. 12. Thick Filament: Myosin www.freelivedoctor.com
  13. 13. Development of Myofibers from Myoblasts Some Myoblasts do not fuse satelite cells in endomysium regeneration of muscle www.freelivedoctor.com
  14. 14. Motor Units <ul><li>= All muscle fibers that are controlled by a single motor neuron </li></ul><ul><li>The lower the ratio of muscle fibers to neurons, the more precise the movement can be! </li></ul><ul><li>Few cases 1: 1 relationship. Where? </li></ul><ul><li>Most cases: many muscle fibers (up to 2,000) : 1 motor neuron. Where? </li></ul>www.freelivedoctor.com
  15. 15. Muscle Control <ul><li>Muscle tone = Resting tension of skeletal muscles (continuous contraction of some motor units to maintain some muscle tension) </li></ul><ul><li>Recruitment or Multiple motor unit summation </li></ul><ul><li>Maximal tension production: ? </li></ul>www.freelivedoctor.com
  16. 16. Muscle Hypertrophy vs. Atrophy <ul><li>Hypertrophy due to anaerobic exercise </li></ul><ul><li>Leads to increased muscle size - how? </li></ul><ul><li>Atrophy if supply of myofilaments exceeds demand. Muscle fibers become smaller and weaker. </li></ul><ul><li>Eventual death of muscle fibers is irreversible! Importance of Physical Therapy </li></ul>www.freelivedoctor.com
  17. 17. Three Types of Muscle Fibers <ul><li>1) Fast ( or White ) Fibers </li></ul><ul><li>Fast contraction after nervous stimulation </li></ul><ul><li>Large diameter </li></ul><ul><ul><li>large glycogen reserve </li></ul></ul><ul><ul><li>few mitochondria </li></ul></ul><ul><ul><li>densely packed myofibrils </li></ul></ul><ul><li>Fatigue fast due to mainly anaerobic respiration </li></ul>www.freelivedoctor.com
  18. 18. 2) Slow (or Red) Fibers <ul><li>Slower but continuous contraction for extended periods </li></ul><ul><li>Smaller diameter (~ half) </li></ul><ul><ul><li>contain myoglobin </li></ul></ul><ul><ul><li>more capillaries </li></ul></ul><ul><ul><li>more mitochondria </li></ul></ul><ul><li>Do not fatigue as fast due to ? </li></ul>Fig 9-13 www.freelivedoctor.com
  19. 19. 3) Intermediate Fibers <ul><li>Have attributes inbetween fast and slow types </li></ul><ul><li>Most skeletal muscles contain mixture of fiber types. Proportion of fast to slow depends on ___________? </li></ul><ul><li>One motor unit only contains one fiber type </li></ul><ul><li>Eye, hand: ____ fibers dominate </li></ul><ul><li>Back, calf: ____ fibers dominate </li></ul>www.freelivedoctor.com
  20. 20. Organization of Skeletal Muscle Fibers <ul><li>Effect of individual muscle contraction determined by: </li></ul><ul><ul><li>arrangement of muscle fibers </li></ul></ul><ul><ul><li>way of attachment to skeletal system </li></ul></ul><ul><li>Bundles of muscle fibers = </li></ul><ul><li>Muscle fibers within 1 fascicle are parallel </li></ul><ul><li>4 types of fascicle organization </li></ul>www.freelivedoctor.com
  21. 21. Parallel Muscels <ul><li>Majority </li></ul><ul><li>Spindle shaped with cord-like tendons </li></ul><ul><li>Some flat bands with broad _____ on each end </li></ul><ul><li>Examples: ? </li></ul>www.freelivedoctor.com
  22. 22. Convergent muscels <ul><li>Broad origin, pointed insertion </li></ul><ul><li>Direction of pull can be varied: versatility!! </li></ul><ul><li>Example </li></ul>www.freelivedoctor.com
  23. 23. Pennate Muscles: Unipennate <ul><li>One or more tendons run though muscle body </li></ul><ul><li>Fascicles in oblique angle to tendon </li></ul><ul><li>Can generate more tension </li></ul><ul><li>Example </li></ul>www.freelivedoctor.com
  24. 24. Pennate Muscles: Bipennate & Multipennate Example Example www.freelivedoctor.com
  25. 25. Circular Muscles <ul><li>= Sphincters </li></ul><ul><li>Concentric fibers adjust opening </li></ul><ul><li>Examples: orbicularis occuli and oris </li></ul>www.freelivedoctor.com
  26. 26. Muscle Terminology <ul><li>Origin stationary </li></ul><ul><li>Insertion moves </li></ul><ul><li>Possible: multiple origins </li></ul>www.freelivedoctor.com
  27. 27. Types of Actions <ul><li>flexion, extension </li></ul><ul><li>adduction, abduction </li></ul><ul><li>elevation, depression </li></ul><ul><li>rotation, circumduction </li></ul><ul><li>pronation, supination </li></ul><ul><li>etc. . . . . </li></ul>www.freelivedoctor.com
  28. 28. Grouping of Muscles according to Primary Action <ul><li>Agonist = Prime Mover </li></ul><ul><li>Antagonist (action opposes agonist) </li></ul><ul><li>Synergists = Assistants of prime mover </li></ul>www.freelivedoctor.com
  29. 29. Pectoral Girdle www.freelivedoctor.com
  30. 30. Anterior Thorax <ul><li>Deltoid </li></ul><ul><ul><li>IM injection site </li></ul></ul><ul><li>Pectoralis </li></ul><ul><ul><li>Major and minor </li></ul></ul><ul><li>Serratus anterior </li></ul>www.freelivedoctor.com
  31. 31. Pectoral Girdle www.freelivedoctor.com
  32. 32. The Arm, Anterior Aspect <ul><li>Biceps Brachii </li></ul><ul><ul><li>Two Heads </li></ul></ul><ul><ul><li>Origin: Coracoid and Supraglenoid tubercle </li></ul></ul><ul><ul><li>Insertion: Radial Tubercle </li></ul></ul><ul><li>Brachialis </li></ul><ul><li>Brachioradialis </li></ul><ul><li>Digital Flexors </li></ul>www.freelivedoctor.com
  33. 33. The Arm, Posterior Aspect <ul><li>Triceps Brachii </li></ul><ul><ul><li>Three Heads: </li></ul></ul><ul><ul><ul><li>Long </li></ul></ul></ul><ul><ul><ul><li>Lateral </li></ul></ul></ul><ul><ul><ul><li>Medial </li></ul></ul></ul><ul><li>Carpal Extensors </li></ul><ul><li>Digital Extensors </li></ul><ul><li>Extensor retinaculum </li></ul>www.freelivedoctor.com
  34. 34. The Hand, Dorsal Aspect <ul><li>Extensor retinaculum </li></ul><ul><li>Extensor tendons </li></ul>www.freelivedoctor.com
  35. 35. The Hand, Palmar Aspect <ul><li>Flexor Retinaculum AKA Transverse Carpal Ligament </li></ul><ul><li>Carpal Tunnel </li></ul><ul><ul><li>Irritates the median nerve </li></ul></ul>www.freelivedoctor.com
  36. 36. The Pelvis www.freelivedoctor.com
  37. 37. The Thigh: Anterior View <ul><li>Quadriceps Group (4 heads) converge as the Quadriceps Tendon </li></ul><ul><ul><li>Vastus Lateralis </li></ul></ul><ul><ul><li>Vastus Medialis </li></ul></ul><ul><ul><li>Rectus Femoris </li></ul></ul><ul><ul><li>Vastus intermedius </li></ul></ul><ul><li>Iliotibial Tract </li></ul><ul><li>Sartorius </li></ul><ul><ul><li>Longest muscle in body </li></ul></ul>www.freelivedoctor.com

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