Musculoskeletal

1. Musculoskeletal

2. Skeletal System

3. The Skeletal System • Consists of: • Bones • Cartilage • Ligaments • Connect Bone to Bone • Tendons • Connect Muscle to Bone • Accounts for 20% of body weight • They are living tissue

4. Functions • Support • Supports organs and against gravity • Protection • Protects soft organs underneath • Movement • Muscles attached provide movement • Storage • Inner matrix has Ca salts, Fat in Yellow Bone Marrow • Blood Cell Formation • Hematopoesis in the Red Bone Marrow

5. Structure • Types: • Compact • Spongy • Classifications • Long • Femur, Ulna, Radius, Tibia, Fibula • Short • Tarsals and Carpals • Flat • Cranial bones • Irregular • Vertebrae

6. General Features of the Long Bone Epiphyseal Plate Diaphysis Epiphysis Each bone has surface markings that make it unique Medullary Cavity Periosteum Endosteum

7. Divisions • Contains 206 named bones • Two divisions • Axial Skeleton • Appendicular Skeleton

8. Divisions • Axial Skeleton • 80 bones form the vertical axis • Include: • Cranium • Vertebrae • Sternum • Ribs

9. Axial Skeleton • Skull • 28 separate bones • Hyoid bone

12. Axial Skeleton • Vertebral column • Consists of approximately 33 bones divided into 5 regions • 7 cervical vertebrae • C1 (Atlas) – Yes • C2 (Axis) - No • 12 thoracic vertebrae • 5 lumbar vertebrae • 1 sacral bone (5 fused vertebrae) • 1 coccygeal bone (3-5 fused vertebrae)

14. Thoracic Cage • Protects vital organs in the thorax • Prevents collapse of the thorax during respiration • 12 pairs of ribs • Sternum • Manubrium • Body • Xiphoid process

15. Appendicular Skeleton • 126 Bones • Consists of the bones of the upper and lower extremities and their girdles • Pectoral girdle • Comprised of the scapula and clavicle • Attaches upper limbs to the axial skeleton

16. Upper Extremity • Humerus • Second largest bone in the body • Radius and Ulna • Wrist

17. Pelvic Girdle • Attaches legs to trunk • Consists of two hip bones (coxae) • Acetabulum

18. Legs • Femur • Longest bone in the body • Head articulates with the acetabulum • Articulates distally with patella • Tibia • Larger than fibula and supports most of leg's weight • Distal end forms lateral malleolus, forming medial side of ankle joint • Fibula • Does not articulate with femur • Does articulate with tibia • Distal end forms lateral malleolus, forming lateral aspect of ankle joint

19. Foot • Consists of tarsals, metatarsals, and phalanges • Talus articulates with tibia and fibula • Calcaneus

20. Biomechanics of Movement • Every bone (except the hyoid bone) connects to at least one other bone • Three major classifications of joints • Fibrous joints • Cartilaginous joints • Synovial joints

21. Fibrous Joints • Consist of two bones--united by fibrous tissue—that have little or no movement • Sutures (seams between flat bones)

22. Cartilaginous Joints • Unite two bones by means of hyaline cartilage (synchondroses) or fibrocartilage (symphyses) • Synchondroses • Slight motion (between ribs and sternum) • Symphysis • Slight motion, flexible (symphysis pubis)

23. Plane or gliding joints Saddle joints Hinge joints Pivot joints Ball-and-socket joints Ellipsoid joints Synovial Joints • Contain synovial fluid • Allow movement between articulating bones • Account for most joints of appendicular skeleton

26. Muscular System

27. Characteristics • Excitability • The ability to receive and respond to stimulus • Contractility • The ability to contract • Extensibility • The ability to stretch (opposing pairs) • Elasticity • The ability to recoil to original shape

28. Functions • Movement • Posture • Joint stability • Heat Production

29. Types • Smooth • Involuntary • Found in the walls of organs • Ex: Intestinal tract • Skeletal • Voluntary • Cardiac • Found only in cardiac muscle

30. Structure • As a whole each muscle may be made up of hundreds of muscle fibers • Fascia surrounds and separates each muscle • Each muscle is surrounded by a protective sheath called epimysium which divides the muscle into compartments • Each compartment contains a bundle of fibers called a fasciculus surrounded by a layer of tissue called perimysium • Each fiber in the fasciculus is surrounded by a layer of tissue called the endomysium • The coverings also contain blood vessels and nerves

31. Structure Muscle Fibers • Each fiber is a cylindrical cell • The cell membrane is called the sacrolemma • The cytoplasm is the sarcoplasm • A special Endoplasmic Reticulum in the sarcoplasm is called the sarcoplasmic reticulum • The sarcolemma has multiple nuclei and mitochondria (for energy production) • Inward extensions of the sacrolemma are called T-tubules

32. Structure Muscle Fibers SACROMERE

33. Nerve & Blood Supply • Have an abundant supply • Before a muscle can contract it needs a stimulus • This requires ATP • Blood supply deliver O2 and nutrients to produce this and remove the waste products • One Artery and One Vein accompany each nerve

34. Contraction • Stimulated by specialized nerve cells called motor neurons • The motor neuron and muscle(s) is called a motor unit • Where the axon of the neuron meets the muscle is called the neuromuscular junction • Between the two is a small depression in the muscle membrane called the synaptic cleft

35. Contraction • ACh is contained within the synaptic vesicles of the axon • Receptors for ACh are in the sacrolemma • The combination results in a stimulus for contraction (an impulse) which travels along the sacrolemma into the T-tubules where a physiological change occurs causing a contraction • The enzyme acetylcholinesterase deactivates the ACh at the synaptic cleft

36. Sacromere Contraction • In a relaxed muscle fiber myosin receptor sites on the actin are inactive • Heads on the myosin are also inactive and are bound to ATP • Ca is stored in the sarcoplasmic reticulum and has a low concentration in the sarcoplasm • An impulse into the T-tubule cause release of Ca from the SR into the sarcoplasm • This rapid influx changes configuration of troponin on the actin fibers which exposes receptor sites

37. Sacromere Contraction • Simultaneously ATP is broken down to ADP which gives energy to the myosin • This energy allows it to interact with the actin • The myosin heads bind forming cross-bridges and rotate pulling the actin towards the center of the myosin (Power stroke) • This pulls the Z line closer together shortening the sacromere • This does not shorten the myofilament • New ATP on myosin reverse the reaction • This is the “Sliding Filament Theory”

38. Sacromere Contraction • When the stimulation ceases, Ca is actively transported into the SR • This causes the receptor sites to close and ceasing the contraction • Follows the All-or-none Principle, which is basically: • A sufficient stimulus is need to cause a contraction (threshold stimulus) • A greater stimulus will not produce greater contraction • Not enough will elicit no response (sub-threshold stimulus)

39. Whole Muscle Contraction • Does not follow All-or-none • Varies due to work load • Increase contraction is achieved by motor unit summation and wave summation • A single stimulus causes a twitch (lab setting) • 3 stages of contraction • lag phase • contraction • relaxation

40. Whole Muscle Contraction • A stimulus given during relaxation phase will cause stronger contraction, and continues to build to form a smooth contraction called tetany (multiple wave summation) • Treppe (staircase) shows an increase in force with a stimulus of same intensity • Muscle tone is the continued state of partial contractions of the muscles (needed for posture and temp) • If movement occurs it is an isotonic contraction • If there is no movement then it is isometric

41. Energy Sources • Initial Source • ATP for the cross-bridge and active transport • Last only 6 seconds • Second Source • Creatine Phospate is used to instantaneously give its energy to ADP to synthesis ATP • If ATP is in excess it will convert to Creatine phosphate to store for later use • Lasts only 10 seconds

42. Energy Sources • Third Stage • Muscles use fatty acids and glucose for energy • Fatty acids found in blood • Glucose is a derivative of the glycogen found in the muscle • If oxygen available then the fats and glucose are broken down with aerobic metabolism (20 times more production) Fatty Acids or glucose + O2→ CO2 + H20 + ATP • If oxygen is not available then glucose is the primary source of energy (anaerobic metabolism – happens at a faster rate) Glucose→ lactic acid + ATP

43. Energy Sources • Oxygen storage • Red fibers have myoglobin which has iron to bind with O2 • White Fibers do not contain myoglobin • Lactic Acid • Excessive lactic acid is send to the liver when O2 is available and converted and stored as glycogen • Oxygen Debt • After strenuous exercise using anaerobic metabolism, ATP and creatine phosphate have to be replaced, this requires O2 • Is the additional O2 needed to do this after exercise

44. Musculoskeletal Injury

45. Injury to Muscle • Can occur due to: • Overexertion where fibers are broken • With trauma muscles can be bruised, crushed, cut, or even torn even without a break in the skin. • Injured muscles tend to be: • Swollen, tender and painful, weak

46. Classification of MS Injuries • Injuries that result from traumatic forces include: • Fractures • Sprains • Strains • Dislocations

47. Complications • Hemorrhage • Instability • Loss of tissue • Simple laceration and contamination • Interruption of blood supply • Nerve damage • Long-term disability

48. Sprains, Strains and Dislocations • Ligaments • BONE to BONE • Tendons • MUSCLE to BONE • Sprain is an injury to a ligament • Strains are injuries to tendons or muscles • Dislocations are bones of a joint that are separated from normal position of use

49. Sprains • A partial tearing of a ligament caused by a sudden twisting or stretching of a joint beyond its normal range of motion • Ankle and knees are most common • Sprains are graded by severity: • First degree • Ligaments are stretched but not torn • Can put weight on the ankle • Second degree • Ligament is partially torn, pain and swelling are greater • Painful with weight • Third degree • Cannot handle weight

50. Strains • An injury to the muscle or its tendon from overexertion or overextension • Commonly occur in the back and arms (welcome to EMS) • May be accompanied by significant loss of function • Severe strains may cause an avulsion of the bone from the attachment site