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P M S 1 Intro (Updated)






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P M S 1  Intro (Updated) P M S 1 Intro (Updated) Presentation Transcript

  • Introduction to Muscloskeletal system
    MBChB, MPH
  • Musculoskeletal System
    The musculoskeletal system is the organ system that gives us the ability to move (locomotion). The primary functions of this system include:
  • Skeletal System
    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.
  • 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.
    • 6. Triglyceride Storage
    • Yellow bone marrow
    • Triglycerides stored in adipose cells
    • Serves as a potential chemical energy reserve
    7. Heat generation
  • The musculoskeletal system is comprised up of the following tissues:
    Cartilage, Ligaments, Tendons
  • Muscles
  • Anatomy and Physiology
    Skeletal, smooth, and cardiac
    The junction between two or more bones
    Cord-like structures that attach muscles to the periosteum of the bone
    Attachments of the muscle
    Origin and insertion
  • Anatomy and Physiology
    Fibrous tissue connecting two adjacent, freely movable bones
    Firm, dense type of connective tissue
    Small sac filled with synovial fluid
    Reduces friction between areas
  • Musculoskeletal System
  • Ligaments
    • Ligaments connect bone-to-bone or reinforce joints--they are made up of tendinous tissue as well
    • E.g. knee ligaments
  • Tendons
    Tendons are calble-like fibrous tissues that connect muscle-to-bone, functioning simply to transmit forces
  • Joints
  • Copyright 2010, John Wiley & Sons, Inc.
    Points where bones meet
    Structurally: by their anatomy
    Fibrous, cartilaginous, or synovial
    Functionally: by the degree of movement they permit
    Immovable, slightly movable, and freely movable
  • Structural Classification
    Based on what is between bones:
    Space (or not)
    Type of connective tissue present
    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
  • Functional Classification
    Based on degree of movement they permit
    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
  • Fibrous Joints
    Suture (synarthrosis)
    Joined by thin layer of dense fibrous connective tissue
    Example: between bones of skull
    Greater distance between bones and greater amount of dense irregular connective tissue
    Distal tibia to distal fibula (amphiarthrosis)
    Gomphosis (synarthrosis): tooth root in socket (alveolar process) of mandible or maxilla
  • Fibrous Joints
    Interosseous membrane (amphiarthrosis)
    Has greater amount of dense irregular connective tissue
    Examples: extensive membranes between shafts of some long bones
  • Fibrous Joints
  • Fibrous Joints
  • Fibrous Joints
  • Cartilaginous Joints
    Synchondrosis (synarthrosis)
    Cartilage connects two areas of bone
    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
  • Copyright 2010, John Wiley & Sons, Inc.
    Cartilaginous Joints
  • Cartilaginous Joints
  • 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.
  • 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.
  • 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
  • Synovial Joints: Structure
    In some cases synovial joints include:
    Ligaments (either inside or outside of joint cavity)
    Menisci (cartilage discs)
    Articular fat pads
    Sacs made of synovial membranes containing fluid
    Located where friction can occur
    Examples: between skin-bone, tendons-bones, muscles-bones, ligaments-bones
  • Copyright 2010, John Wiley & Sons, Inc.
    Synovial Joints: Structure
  • Copyright 2010, John Wiley & Sons, Inc.
    Knee Joint
  • 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
  • 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
    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
    Movement may be restricted if a joint has not been used for an extended period
  • Bone and cartilage
  • 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
  • Elastic: More flexible, e.g., ear
  • Hyaline
    usually in the joints
  • Fibrocartilage
    Resists compression—IV Disk, menisci
  • Types (shapes) of Bones
  • 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.
  • 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.
  • 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.
    Vascular tissue.
    Lymphatic tissue.
    Adipose tissue.
    Nervous tissue.
  • Types of Osseous Tissue
    Compact Bone
    Dense, found in the walls, or cortex
    Spongy or Cancellous Bone
    Network of struts and thin plates (trabeculae)
    Red and Yellow
  • 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:
  • Skeletal System
    Inorganic component of bone matrix
    Consists mainly of two components :
    Calcium phosphate.
    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.
  • 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.
  • 47
  • 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
  • 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.
  • Typical (Long) Bone Structure
  • Internal Organization of a Typical Bone
    Osteon = Functional unit of bone
  • 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
    Osteoclasts break down bone
  • 2. Spongy Bone
    No osteons
    Lacy network of struts called trabeculae reinforce the bone
    Covered by endosteum
  • 3. Marrow
    Red Marrow
    Blood Precursors
    Yellow Marrow
    Mostly fat
  • 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.
  • Skeletal System
    Bone Marrow
  • 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.
  • 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
  • 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
  • The blue arrows indicate the osteoblasts. The yellow arrows indicate the bone matrix they’ve just secreted.
  • Skeletal System
    Mature bone cells.
    Osteoblasts that have become trapped by the secretion of matrix.
    No longer secrete matrix.
    Responsible for maintaining the bone tissue.
  • Skeletal System
    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.
  • 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.
  • 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
  • Bone Circulation