Lesson 5.1: Muscle Tissue Categories and Functions Lesson 5.2: Skeletal Muscle Actions

1. 5 Lesson 5.1: Muscle Tissue Categories and Functions Lesson 5.2: Skeletal Muscle Actions Lesson 5.3: The Major Skeletal Muscles Lesson 5.4: Common Injuries and Disorders of Muscles The Muscular System

2. Lesson 5.1 Muscle Tissue Categories and Functions Chapter 5: The Muscular System

3. Muscle Tissue • Categories • skeletal • smooth • cardiac • Functions • behavioral properties • tension and types of skeletal muscle contractions

4. Muscle Tissue Categories • skeletal • voluntary • striated • smooth • involuntary • no striations • cardiac • involuntary • striated • intercalated disks

5. Muscle Tissue Categories

6. Skeletal Muscle Organization Sarcolemma and endomysium surrounds the muscle fiber Perimysium bundles groups of muscle fibers to make up a fascicle Epimysium encloses several fascicles to make up a muscle Aponeurosis connects muscle to other tissues

7. Skeletal Muscle Organization

8. Behavioral Properties of Muscle extensibility–stretch elasticity–snap back irritability–respond contractility–shorten

9. Muscle Tissue Functions • tension and types of skeletal muscle contraction • agonist–moves bone • antagonist–opposes the movement of the agonist

10. Concentric Contraction agonist contracts, antagonist relaxes

11. Eccentric Contraction agonist contracts while lengthening, antagonist relaxes

12. Isometric Contraction both agonist and antagonist contract

13. Lesson 5.2 Skeletal Muscle Actions Chapter 5: The Muscular System

14. Skeletal Muscle the motor unit skeletal fiber types muscular strength, power, and endurance

15. The Motor Unit group of muscle fibers under the control of one motor neuron 100-2000 fibers, depending on size and function of muscle

16. Generating Action Potentials • Acetylcholine crosses the synaptic cleft at the neuromuscular junction (neurotransmitter) • Na+ rushes in, K+ rushes out->creates POSITIVE charge (Depolarization) • More Na+ enters- Action potential begins

17. Contraction of the Sarcomeres Number and frequency of action potentials determine speed and force of contraction! Fed by glycogen (stored glucose) Triggered by Ca++ release Sarcomeres shorten by actin filaments (heads grabbing) sliding along myosin filaments

18. Maximum Tension and Return to Relaxation Action potential always causes entire motor unit muscle fibers to contract- then it must FULLY relax before a new stimulus can be applied All-or-none law Multiple motor units must be stimulated to produce maximum tension Sustained maximum tension=tetanus

19. Skeletal Muscle Fiber Types Type 1 - Slow-twitchcontracts relatively slowly and is resistant to fatigue Type IIa - These fast twitch muscle fibers are also known as intermediate fast-twitch fibers. Moderate fatigue Type IIb - This fast twitch muscle fiber has the highest rate of contraction (rapid firing) of all the muscle fiber types, but it also has the highest rate of fatigue. All muscle fibers in a motor unit are the same type, but not all motor units in a muscle are!

20. Skeletal Muscle Fiber Architecture • parallel fiber arrangements- large range of motion • Fusiform- biceps brachii • Bundled- rectus abdominus • Triangular- pectoralis major • pennate fiber arrangements- Oblique attachment gives force, Does not shorten as much • Unipennate- abductor pollux • Bipennate- rectus femoris • Multipennate-deltoid

21. Muscular Strength • Rotary force that muscles can produce at a joint • the maximum weight you can lift is a measurement of muscular strength ONLY (no variable for speed)

22. Muscle Power • force x velocity (both force and speed contribute equally, so strength is not the determining factor) • how fast you can sprint is a measurement of muscle power

23. Muscle Endurance • Muscle tension/time • Can be sustained or cyclical- varies based on activity • how far you can run is a measurement of muscle endurance • So is rowing • Handstands • Cycling

24. Fatigue • Opposite of endurance • Affected by: • Nature of work/exercise done • How often the muscle is used • Muscle fiber composition • Humidity/temperature of enviornment

25. Lesson 5.3 The Major Skeletal Muscles Chapter 5: The Muscular System

26. The Major Skeletal Muscles directional motions head and neck muscles trunk muscles upper limb muscles lower limb muscles

27. Skeletal Muscle Attachments • Origin • fixed end of a muscle • Insertion • movable end of a muscle

28. Sagittal Plane MovementsAnterior and Posterior Flexion- forward (except knee) Extension- back to normal position Hyperextension- too far Dorsiflexion- toes toward body Plantar flexion- “gas pedal”- point toes

29. Frontal Plane MovementsMedial and Lateral • Abduction- limb lateral • Adduction-limb medial • Inversion-foot medial • Eversion-foot lateral • radial deviation- Hand lateral at wrist • ulnar deviation- Hand medial at wrist

30. Transverse Plane MovementsRotational Medial rotation-toward midline Lateral rotation- away from midline Pronation- palm down Supination- palm up

31. Multiplanar MovementsNot in a single plane Circumduction- make a circle Opposition- thumb to any of the other 4 fingers

32. Head and Neck MusclesAll except orbicularis Oris and Platysma are paired

33. Trunk Muscles- Posture, stability and protection

34. Upper Limb Muscles- NOT all of them (just the major ones)

35. Lower Limb Muscles- (just the major ones)

36. Lesson 5.4 Common Injuries and Disorders of Muscles Chapter 5: The Muscular System

37. Muscle Injuries • Strain – overstretched muscle (less common in the more flexible, speed at time of injury is a factor as well) • grade I- mild: tightness 1 day • grade II- moderate: partial tear, temporary weakness and loss of function • grade III- severe: torn muscle, loss of function, internal bleeding, swelling. EX: Hamstring strains most common, tend to reoccur, slow to heal (1/3 repeat within 1 year)

38. Muscle Injuries • Contusion – bruised muscle from impact • myositis ossificans • When an already injured muscle is struck, forms calcium mass over 3-4 weeks. Reabsorbs after 6-7 weeks (usually) • Cramps – spasming muscle • Numerous causes: electrolyte imbalance, Ca, Mg, K deficiency, dehydration, idiopathic • Delayed onset muscle soreness – begins 24-48 hours later, multiple, microscopictears= pain, swelling and stiffness

39. Tendon Injuries Val Thoermer/Shutterstock.com Tendinitis –inflamed tendon Tendinosis –degeneration of a tendon leading to rupture. No inflammation

40. Joint / Stress Injuries • Rotational injury at shoulder • improper mechanics • Overuse of elbow- epicondylitis • Medial (little leaguer) tears • lateral tears (tennis elbow) tears • Shin splints- periosteum • Tibial tendons • Whiplash- abnormal motion • Cervical vertebrae, • muscle spasms • Attempt to protect spine

41. Muscle Disorders • Hernia - A hernia is the protrusion of an organ or the fascia of an organ through the muscular wall of the cavity that normally contains it. • Complications include strangulation • Repair with surgery • Various causes • Heavy lifting • Increased abdominal pressure • Present at birth

42. Muscle Disorders Muscular dystrophy - a group of inherited, progressive disorders that involve muscle weakness and loss of muscle tissue, varies in severity. No cure.