1. Skeletal Muscle Tissue
Chapter 10

2. Introduction Muscles are responsible for movement
Contraction & relaxation
Muscles make up 40 – 50 % of a human’s total body weight

3. Characteristics of Muscle Tissue
Excitability
Can receive & respond to stimuli
Contractility
Can shorten & thicken
Extensibility
Can be stretched
Elasticity
Can return to its original shape

4. Functions of Muscle Tissue
Motion
Maintenance of posture
Heat production

5. Kinds of Muscle Tissue
Skeletal Muscle
Cardiac Muscle
Smooth Muscle

6. The Muscular System Muscle tissue = all contractile tissue
Skeletal muscle tissue
Connective tissue

7. Fascia of Skeletal Muscle
Epimysium
Wraps muscle
Perimysium
Divides muscle into bundles (fasciculi)
Endomysium
Separates each muscle cell
Human Anatomy, 3rd edition
Prentice Hall, © 2001

8. Fascia of Skeletal Muscle
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Title: Structural Organization of Skeletal Muscle
Notes: A skeletal muscle consists of bundles of muscle fibers (fascicles) enclosed within the epimysium. The fascicles are ensheathed by the perimysium, and within each fascicle the individual muscle fibers are surrounded by the endomysium.
Keywords: skeletal muscles, fascicles, muscle fibers, epimysium, connective tissue, perimysium, endomysium, nuclei, mitochondria, myofibril, sarcoplasm, sarcolemma, tendon
Human Anatomy, 3rd edition
Prentice Hall, © 2001

9. Human Anatomy, 3rd edition
Tendons & Aponeuroses
Epimysium
Perimysium
Endomysium
Human Anatomy, 3rd edition
Prentice Hall, © 2001

10. Human Anatomy, 3rd edition
Tendon Sheaths
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Title: Intrinsic Muscles, Tendons, and Ligaments of the Hand
Notes: Anatomy of the right wrist and hand. (a)Posterior view. (b) Origins and insertions, posterior.(c)Origins, insertions;anterior. (d)Anterior view. (e)Plastic reconstruction, posterior. (f)Anterior view;muscle dissection.
Keywords: wrist, hand, muscles, tendons, extensor indicis tendon, extensor pollicis longus, radial artery, extensor carpi radialis longus, extensor carpi radialis brevis, collateral ligament, extensor digiti minimi, extensor digitorum, dorsal interossei
Human Anatomy, 3rd edition
Prentice Hall, © 2001

11. Human Anatomy, 3rd edition
Nerve & Blood Supply
Related to contraction
Artery and 1 or 2 veins accompany each nerve
Each muscle cell is in contact with capillaries
Each muscle cell is in contact with a portion of a nerve cell
Neuromuscular junction
Human Anatomy, 3rd edition
Prentice Hall, © 2001

12. Histology of Skeletal Muscle Tissue
Muscle fibers = elongated cells
Sarcolemma
Sarcoplasm
Sarcoplasmic reticulum
T tubules
Triad
Muscle fibers consist of myofibrils
Extend length of fiber
Myofibrils consist of myofilaments
Thin filaments
Thick filaments
Human Anatomy, 3rd edition
Prentice Hall, © 2001

13. Human Anatomy, 3rd edition
Myofilaments
Myofilaments do not extend entire length of fiber.
Stacked in compartments = sarcomeres
Partitioned by Z lines
A band (dark) – contains thick filaments
Includes H zone, zone of overlap
I band (light) – thin filaments only
H zone – thick filaments only
Human Anatomy, 3rd edition
Prentice Hall, © 2001

14. Human Anatomy, 3rd edition
Myofilaments
Thin filaments
Composed mostly of actin
Contain tropomyosin and troponin
Double-stranded coil
Thick filaments
Composed mostly of myosin
Rod-shaped (tail) with head
Human Anatomy, 3rd edition
Prentice Hall, © 2001

15. Contraction – Sliding Filament Theory
Thin filaments slide inward toward the H zone
Z lines are drawn toward the A band
Sarcomere shortens
Lengths of myofilaments do not change
Cross bridges of thick filaments connect with actin
Width of the H zone gets smaller
Human Anatomy, 3rd edition
Prentice Hall, © 2001

16. Neuromuscular Junction
Contraction requires a stimulus
An axon comes into close contact with a muscle membrane
Motor end plate
Acetylcholine transmits nerve impulse to the motor end plate
Initiates contraction
Axon terminal + motor end plate = neuromuscular junction
Human Anatomy, 3rd edition
Prentice Hall, © 2001

17. Human Anatomy, 3rd edition
Motor Unit
Def. – motor neuron and all muscle cells it stimulates
1 motor neuron may innervate few or many muscle cells
The number of muscle fibers/motor unit determines how precise a movement is.
Human Anatomy, 3rd edition
Prentice Hall, © 2001

18. Physiology of Contraction – Relaxed Muscle
Sarcoplasm is low in calcium
ATP is bound to myosin cross bridges
Tropomyosin-troponin complex is attached to actin
Human Anatomy, 3rd edition
Prentice Hall, © 2001

19. Physiology of Contraction – Stimulation of Muscle
Nerve impulse reaches motor end plate
Neuron releases ACh
Electrical charge travels along sarcolemma
Electrical charge travels down T tubules
Electrical charge travels to S.R.
S.R. releases calcium into sarcoplasm

20. Physiology of Contraction – Activation of Myosin
Calcium binds to troponin
Cross bridges form
Calcium acts as an enzyme
Breaks down ATP to ADP + P
Myosin cross bridges move
Sarcomere shortens
Muscle shortens

21. Physiology of Contraction – Relaxation of Muscle
Nerve impulse ends
ACh is broken down by acetylcholinesterase
Calcium is actively transported back into S.R.
ADP + P = ATP
Binds to cross bridges
Myosin cross bridges separate from actin
Binding sites on actin are covered
Thin myofilaments slip back to resting position
Sarcomeres return to resting length
Muscle fiber returns to resting length

22. Physiology of Contraction
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Title: The Events in Muscle Contraction
Notes: Stepwise summary of the sequence of events in a muscle contraction from neural activation through contraction to rest.
Keywords: muscle contraction, summary, motor end plate, synaptic terminal, T-tubule, action potential, receptor, sarcoplasmic reticulum, calcium, active site, cross-bridge, actin, myosin, acetylcholinesterase, relaxation
Human Anatomy, 3rd edition
Prentice Hall, © 2001

23. Fast, Slow, and Intermediate Muscles
Duration of contraction varies with function
Fast muscles (white)
More extensive SR
Lack myoglobin
Fewer capillaries
Slow muscles (red)
Smaller fibers
More capillaries
Lots of myoglobin

24. Disorders Fibrosis Fibrositis Fibromyalgia Muscular dystrophy
Myasthenia gravis

25. Classifications in the Muscular System

26. How Skeletal Muscles Produce Movement
Exert force on tendons
Attached to articulating bones forming a joint
When muscle contracts, one bone moves toward the other
Attachments
Origin = attachment to stationary bone
Insertion = attachment to moveable bone
Belly = fleshy portion of muscle between tendons

27. Arrangement of Fasciculi
Parallel
Convergent
Pennate
Unipennate
Bipennate
Multipennate
Circular
Arrangement is correlated with the power and range of movement of a muscle.

28. Arrangement of Fasciculi
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Title: Skeletal Muscle Fiber Organization
Notes: Four different arrangements of muscle fiber patterns are observed: (a) parallel, (b) convergent, (c) unipennate, (d) bipennate, (e) multipennate and (f) circular.
Keywords: muscle fiber organization, fascicle, muscle, tendon, parallel muscle, convergent muscle, unipennate muscle, bipennate muscle, multipennate muscle, circular muscle
Human Anatomy, 3rd edition
Prentice Hall, © 2001

29. Group Actions Agonist or prime mover Antagonist Causes desired action
Effect is opposite to agonist
Synergist or fixator
Assists agonist

30. Naming of Skeletal Muscles
Direction of muscle fibers
Location
Size
Number of origins
Shape
Origin & insertion
Action