P M S 1 Intro (Updated)


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P M S 1 Intro (Updated)

  1. 1. Introduction to Muscloskeletal system Dr.AMMAR JAWAD MBChB, MPH
  2. 2. Musculoskeletal System • The musculoskeletal system is the organ system that gives us the ability to move (locomotion). The primary functions of this system include:
  3. 3. Skeletal System Functions: 1. Support  The bones of the legs, pelvic, and vertebral column support the weight of the erect body.  The mandible (jawbone) supports the teeth.  Other bones support various organs and tissues. 2. Protection  The bones of the skull protect the brain.  Ribs and sternum (breast bone) protect the lungs and heart.  Vertebrae protect the spinal cord.
  4. 4. Skeletal System 3. Movement  Skeletal muscles use the bones as levers to move the body. 4. Reservoir for minerals and adipose tissue  99% of the body’s calcium is stored in bone.  85% of the body’s phosphorous is stored in bone. 5. Hematopoiesis  All blood cells are made in the marrow of certain bones.
  5. 5.  6. Triglyceride Storage  Yellow bone marrow  Triglycerides stored in adipose cells  Serves as a potential chemical energy reserve • 7. Heat generation
  6. 6. • The musculoskeletal system is comprised up of the following tissues: ▫ Muscles ▫ Bones ▫ Cartilage, Ligaments, Tendons ▫ Joints
  7. 7. Muscles
  8. 8. Anatomy and Physiology • Muscles ▫ Skeletal, smooth, and cardiac • Joints ▫ The junction between two or more bones • Tendons ▫ Cord-like structures that attach muscles to the periosteum of the bone ▫ Attachments of the muscle  Origin and insertion
  9. 9. Anatomy and Physiology • Ligaments ▫ Fibrous tissue connecting two adjacent, freely movable bones • Cartilage ▫ Firm, dense type of connective tissue • Bursae ▫ Small sac filled with synovial fluid ▫ Reduces friction between areas
  10. 10. Musculoskeletal System
  11. 11. •Ligaments connect bone-to-bone or reinforce joints--they are made up of tendinous tissue as well •E.g. knee ligaments Ligaments
  12. 12. Tendons • Tendons are calble-like fibrous tissues that connect muscle-to-bone, functioning simply to transmit forces
  13. 13. Joints
  14. 14. Copyright 2010, John Wiley & Sons, Inc. Joints • Points where bones meet • Classifications ▫ Structurally: by their anatomy  Fibrous, cartilaginous, or synovial ▫ Functionally: by the degree of movement they permit  Immovable, slightly movable, and freely movable
  15. 15. Structural Classification • Based on what is between bones: ▫ Space (or not) ▫ Type of connective tissue present • Types ▫ Fibrous joints - no cavity, just dense irregular connective tissue ▫ Cartilaginous joints - no cavity, bones held together by cartilage ▫ Synovial joints - have synovial cavity, dense irregular tissue of articular capsule, and often ligaments
  16. 16. Functional Classification • Based on degree of movement they permit • Types ▫ Synarthrosis: immovable  Pelvis, sutures, teeth ▫ Amphiarthrosis: slightly movable  Epiphyseal plate, tibia-fibula, vertebrae, pelvic symphysis ▫ Diarthrosis: freely movable  Most joints of the body  All diarthrotic joints are synovial
  17. 17. Fibrous Joints • Suture (synarthrosis) ▫ Joined by thin layer of dense fibrous connective tissue ▫ Example: between bones of skull • Syndesmosis ▫ Greater distance between bones and greater amount of dense irregular connective tissue ▫ Examples  Distal tibia to distal fibula (amphiarthrosis)  Gomphosis (synarthrosis): tooth root in socket (alveolar process) of mandible or maxilla
  18. 18. Fibrous Joints • Interosseous membrane (amphiarthrosis) ▫ Has greater amount of dense irregular connective tissue ▫ Examples: extensive membranes between shafts of some long bones  Radius-ulna  Tibia-fibula
  19. 19. Fibrous Joints
  20. 20. Fibrous Joints
  21. 21. Fibrous Joints
  22. 22. Cartilaginous Joints • Synchondrosis (synarthrosis) ▫ Cartilage connects two areas of bone ▫ Example  Epiphyseal (growth) plate connecting epiphysis and diaphysis of long bone (synarthrosis) • Symphysis (amphiarthrosos) ▫ Cartilage connects two bones, but a broad disc of fibrocartilage is present also ▫ Examples: pubic symphysis and intervertebral discs
  23. 23. Copyright 2010, John Wiley & Sons, Inc.Cartilaginous Joints
  24. 24. Cartilaginous Joints
  25. 25. ▫ Synovial  Most complex joints  Allow a large degree of relative motion between articulating bones  Surrounded by a fibrous capsule (synovial capsule)  Hip, knee, elbow, ankle, etc.
  26. 26. Musculoskeletal System Synovial fluid: The joint capsule secretes whitish fluid that works like oil in a machine, lubricating the joint surfaces to reduce friction to promote smooth operation and extend joint life.
  27. 27. Synovial Joints: Structure • Synovial cavity: space containing fluid • Articular cartilage ▫ Covers ends of bones, absorbs shock • Articular capsule ▫ Inner layer: synovial membrane that secretes synovial fluid (reduces friction, supplies nutrients) ▫ Outer layer: dense, irregular connective tissue
  28. 28. Synovial Joints: Structure • In some cases synovial joints include: ▫ Ligaments (either inside or outside of joint cavity) ▫ Menisci (cartilage discs) ▫ Articular fat pads ▫ Bursae  Sacs made of synovial membranes containing fluid  Located where friction can occur  Examples: between skin-bone, tendons-bones, muscles-bones, ligaments-bones
  29. 29. Copyright 2010, John Wiley & Sons, Inc.Synovial Joints: Structure
  30. 30. Copyright 2010, John Wiley & Sons, Inc.Knee Joint
  31. 31. Joints (Factors Affecting Contact and Range for Motion at Synovial Joints) • Range of motion (ROM) ▫ Refers to the range, measured in degrees of a circle, through which the bones of a joint can be moved • Factors contribute to keeping the articular surfaces in contact and affect range of motion: ▫ Structure or shape of the articulating bones  Shape of bones determines how closely they fit together ▫ Strength and tension of the joint ligaments  Ligaments are tense when the joint is in certain positions  Tense ligaments restrict the range of motion
  32. 32. Joints (Factors Affecting Contact and Range for Motion at Synovial Joints) ▫ Arrangement and tension of the muscles  Muscle tension reinforces the restraint placed on a joint by its ligaments , and thus restricts movement ▫ Contact of soft parts  The point at which one body surface contacts another may limit mobility  Movement be restricted by the presence of adipose tissue ▫ Hormones  Flexibility may also be affected by hormones  Relaxin increases the flexibility of the pubic symphysis and loosens the ligaments between the sacrum and hip bone toward the end of pregnancy ▫ Disuse  Movement may be restricted if a joint has not been used for an extended period
  33. 33. Bone and cartilage
  34. 34. Cartilage: Connective tissue •Chondroblasts lay down the matrix, •become chondrocytes when surrounded by extra cellular matrix •Chondrocytes do not mitose •Poor healing •On aging, cartilage becomes calcified •Less flexible •Not bone
  35. 35. Elastic: More flexible, e.g., ear
  36. 36. • Hyaline ▫ usually in the joints
  37. 37. Fibrocartilage Resists compression—IV Disk, menisci
  38. 38. Types (shapes) of Bones •Long ▫ Femur •Short ▫ Carpal •Sesamoid ▫ Patella •Flat ▫ Scapula •Irregular ▫ Vertebra
  39. 39. 40 Bone • Bone classification There are 206 bones in the human body. • Skeleton system classified into two groups: A. Axial skeleton  Forms long axis of the body.  Includes the bones of the skull, vertebral column, and rib cage.  These bones are involved in protection, support, and carrying other body parts.
  40. 40. 41 Skeletal System B. Appendicular skeleton  Bones of upper & lower limbs and the girdles (shoulder bones and hip bones) that attach them to the axial skeleton.
  41. 41. 42 Skeletal System • Basic Bone Structure • Bones are organs composed of hard living tissue providing structural support to the body. • It is a hard matrix of calcium salts deposited around protein fibers. Minerals make bone rigid and proteins (collagen) provide strength and elasticity. Bones are organs. Thus, they’re composed of multiple tissue types. Bones are composed of: ▫ Bone tissue (osseous tissue). ▫ Fibrous connective tissue. ▫ Cartilage. ▫ Vascular tissue. ▫ Lymphatic tissue. ▫ Adipose tissue. ▫ Nervous tissue.
  42. 42. Types of Osseous Tissue 1. Compact Bone 1. Dense, found in the walls, or cortex 2. Spongy or Cancellous Bone 1. Network of struts and thin plates (trabeculae) 3. Marrow 1. Red and Yellow
  43. 43. 44 Skeletal System • Bone Matrix: ▫ Consists of organic and inorganic components. ▫ 1/3 organic and 2/3 inorganic by weight ▫ Organic component consists of several materials that are secreted by the osteoblasts:
  44. 44. 45 Skeletal System • Inorganic component of bone matrix ▫ Consists mainly of two components : 1. Calcium phosphate. 2. Calcium hydroxide. ▫ These 2 salts interact to form a compound called hydroxyapatite. ▫ Bone also contains smaller amounts of magnesium, ▫ fluoride, and sodium. ▫ These minerals give bone its characteristic hardness and the ability to resist compression.
  45. 45. 46 Skeletal System • Long Bone Structure • Shaft plus 2 expanded ends. • Shaft is known as the diaphysis. ▫ Consists of a thick collar of compact bone surrounding a central marrow cavity • Expanded ends are epiphyses ▫ Thin layer of compact bone covering an interior of spongy bone. ▫ Joint surface of each epiphysis is covered with a type of hyaline cartilage known as articular cartilage.
  46. 46. 47
  47. 47. 49 Skeletal System • The external surface of the entire bone except for the joint surfaces of the epiphyses is covered by a double-layered membrane known as the periosteum. ▫ Periosteum is richly supplied with nerve fibers, lymphatic vessels and blood vessels.  These enter the bone of the shaft via a nutrient foramen. ▫ Periosteum is connected to the bone matrix via strong strands of collagen
  48. 48. 50 Skeletal System • Internal bone surfaces are covered with a delicate connective tissue membrane known as the endosteum. ▫ Covers the spongy bone in the marrow cavities and lines the canals that pass through compact bone. ▫ Contains both osteoblasts and osteoclasts.
  49. 49. Typical (Long) Bone Structure
  50. 50. Internal Organization of a Typical Bone Osteon = Functional unit of bone
  51. 51. 1. Compact Bone • Osteon = functional unit of bone • The mineral matrix is hydroxyapatite • Osteoblasts lay down the matrix in layers (lamellae) ▫ Become osteocytes when surrounded by EC matrix ▫ Lacunae • Osteoclasts break down bone
  52. 52. 2. Spongy Bone • No osteons • Lacy network of struts called trabeculae reinforce the bone • Covered by endosteum
  53. 53. 3. Marrow • Red Marrow ▫ Active ▫ Blood Precursors • Yellow Marrow ▫ Inactive ▫ Mostly fat
  54. 54. 58 Skeletal System • Bone marrow is a general term for the soft tissue occupying the medullary cavity of a long bone, the spaces amid the trabeculae of spongy bone, and the larger haversian canals.  Red bone marrow looks like blood but with a thicker consistency.  It consists of a delicate mesh of reticular tissue saturated with immature red blood cells and scattered adipocytes.
  55. 55. 59 Skeletal System Bone Marrow
  56. 56. 60 Skeletal System • In a child, the medullary cavity of nearly every bone is filled with red bone marrow. • In young to middle-aged adults, the long bones are filled with fatty yellow bone marrow. ▫ Yellow marrow no longer produces blood, although in the event of severe or chronic anemia, it can transform back into red marrow • In adults, red marrow is limited to the axial skeleton, pelvic girdle, and proximal heads of the humerus and the femur.
  57. 57. 61 Skeletal System • Bone tissue is a type of connective tissue consist of cells and a big amount of extra-cellular matrix. • Bone cells: • Osteogenic cells ▫ Undergo cell division; the resulting cells develop into osteoblasts
  58. 58. Osteoblasts Bone-building cells. Synthesize and secrete collagen fibers and other organic components of bone matrix. Initiate the process of calcification. Found in both the periosteum and the endosteum
  59. 59. 63 The blue arrows indicate the osteoblasts. The yellow arrows indicate the bone matrix they’ve just secreted.
  60. 60. 64 Skeletal System Osteocytes  Mature bone cells.  Osteoblasts that have become trapped by the secretion of matrix.  No longer secrete matrix.  Responsible for maintaining the bone tissue.
  61. 61. 67 Skeletal System Osteoclasts ▫ Huge cells derived from the fusion of as many as 50 monocytes (a type of white blood cell). ▫ Cells that digest bone matrix – this process is called bone resorption and is part of normal bone growth, development, maintenance, and repair. ▫ Concentrated in the endosteum.
  62. 62. Bone Development • Osteogenesis (ossification): is the process of bone tissue formation. • In embryos this leads to the formation of the bony skeleton. • In children and young adults, ossification occurs as part of bone growth. • In adults, it occurs as part of bone re-modeling and bone repair.
  63. 63. Formation of the Bony Skeleton • Before week 8, the human embryonic skeleton is made of fibrous membranes and hyaline cartilage. • After week 8, bone tissue begins to replace the fibrous membranes and hyaline cartilage. ▫ The development of bone from a fibrous membrane is called intra- membranous ossification. ▫ Plates of Bone e.g. skull ▫ The replacement of hyaline cartilage with bone is known as endo- chondral ossification. • Long Bones
  64. 64. Bone Circulation