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A 12 year-old boy brought in with right elbow fracture and part of the…

- - - - bone infection
      - wound site infection
  - - - bone prone to fracture
- - - - serve as attachment sites for skeletal muscles, soft tissues, organs
      - bones used as levers by muscles to move body and its parts
    - - skull protect brain, rib cage heart and lungs, vertebrae spinal cord
    - - most importantly calcium and phosphate
      - stored minerals related from bone into blood as needed
    - - provide framework that support body and
  - - - irregular bones
        
        vertebrae, os caxae
        
        complicated shapes, don't fit none of the other categories
      - short bones
        
        length nearly equal to width, cubed shaped
        
        carpal bones( wrist); tarsals ( ankle)
      - sesamoid bones
        
        type of short bone that form in tendon
        
        patella, sesamoid of Hallux(toe); sesamoid of Pollex(thumb)
      - flat bones
        
        thin, flattened , slightly curved
        
        sternum, scapulae, ribs, frontal and parietal bones
        
        interior composed of spongy bone lined on either side by compact bone
        
        no medullary cavity
      - Wormian: sutural bone
        
        small bones between cranial sutures
      - long bones: longer than wide, have medullary cavity
        
        regions of long bone
        
        medullar cavity
        
        contain red bone marrow in children
        
        contain yellow marrow in adults
        
        hollow , cylindrical space within diaphysis
        
        epiphysis
        
        knobby region at each end of long bone
        
        composed of
        
        outer thin layer of compact bone
        
        inner region of spongy bone
        
        proximal epiphysis
        
        end of bone closest to body
        
        distal epiphysis
        
        end farthest from trunk
        
        diaphysis
        
        provides leverage and weight support
        
        compact bone with thin spicules of spongy bone
        
        elongated, cylindrical shaft; runs proximal to distal end of bone
        
        metaphysisis
        
        contains epiphyseal plate/ disc aka growth plate
        
        provides for lengthwise growth
        
        thin layer of hyaline cartilage
        
        region between diaphysis and epiphysis
        
        in adults, epiphyseal line is remnant of epiphyseal plate
        
        articular cartilage: thin layer of hyaline cartilage
        
        covers joint surface
        
        reduces friction, absorbs shock in moveable joints
        
        Membranes coverings and lining of bones
        
        endosteum
        
        covers all internal surfaces of bone within medullary cavity
        
        contains osteogenic cells, osteoblasts, osteoclasts
        
        periosteum
        
        outer fibrous layer of dense irregular CT
        
        contains blood, lymph vessels, nerves that nourish compact bone
        
        attachment site for ligaments and tendons
        
        protects bone from surrounding structures
        
        anchored to bone by collagen fibers
        
        membranous sheath covering outer surface of bone
        
        inner cellular layer
        
        includes osteogenic cells, osteoblasts , osteoclasts
        
        example: humerus, femur
        
        Blood and nerves
        
        epiphysis
        
        epiphyseal arteries
        
        epiphyseal veins
        
        diaphysis
        
        main vessels run trough nutrient foramen
        
        nutrient artery and nutrient vein
        
        nerves accompanied blood vessel through nutrient foramen
        
        mainly sensory nerves
    - - osteoblasts: bone builder
        
        function: bone formation
        
        location
        
        build up bone tissue
        
        adds calcium to bone
        
        cell layer of periosteum/ endosperm
        
        form from osteogenic stem cells
        
        make and secrete collagen matrix
      - osteoclasts: bone polisher
        
        function: bone resorption
        
        location
        
        breaks down old/damaged bone
        
        release calcium into blood
        
        cell layer periosteum/endosteum
        
        large, multinuclear, phagocytic cells
        
        derived from fused blood stem cells
      - osteogenic cells: osteoprogenitor cells
        
        function
        
        develop into osteoblasts
        
        location
        
        cell layer of periosteum and endosperm
        
        stem cells derived from mesenchyme
        
        only bone cell that divide
        
        one will be stem cell
        
        other will be osteoblasts
      - osteocytes: regulator cell
        
        function: maintain mineral concentration of bone
        
        location
        
        entrapped in bone
        
        mature cells that regulate bone health
        
        mature bone cells derived from osteoblasts
        
        maintain mineral concentration of bone matrix by secretion of enzymes
        
        detect mechanical stress on bone
        
        sends signals to trigger deposition of new bone matrix
    - - compact bone 80% of bone mass
        
        called dense or cortical bone
        
        relatively dense connective tissue
        
        microscopic architecture
        
        osteon: basic structural unit of mature compact bone
        
        concentric lamellae
        
        concentric rings of calcified matrix
        
        surround central canal
        
        osteocytes
        
        mature bone cells
        
        maintain bone matrix
        
        found in lacunae: small spaces btw concentric lamellae
        
        central canal or Haversian canal
        
        cylindrical channel at center of osteon
        
        blood and nerves extend trough it
        
        canaliculi
        
        interconnecting channels within bone CT
        
        allow exchange of nutrients , minerals, gases, wastes btw blood vessels and o osteocytes
        
        Volkmann canals: perforating canals
        
        bloods vessels and nerves travel trough
        
        connect central canals, osteon to osteon
        
        perpendicular to central canals
        
        appears white, smooth, solid
      - spongy bone: 20 % of bone mass
        
        called cancellous or trabecular bone
        
        located internal to compact bone
        
        microscopic architectcure
        
        spaces of trabecular network makes bone lighter
        
        red marrow fills spaces in the bone
        
        trabecular form along line of stress to provide strength to bone
        
        osteocytes in lacuna not in concentric circles
        
        trabecular: lattice-like network of matrix spikes
        
        appears porous
  - - - communited: bone fragments in 3/more pieces
      - impacted: one fragment driven into another
      - spiral: break occurs from twisting action
      - greenstick: incomplete break with splintering
      - transverse: straight across
      - oblique: slanted fracture
      - compound/ open: bone protrude through skin
      - traumatic: caused by trauma, stress
      - simple/closed: doesn't pierce skin
      - pathologic: bone weekend by disease
      - compression: bone is crushed
    - - healing slows with age
      - 4 steps of bone fracture repair
        
        fibrocartilagenous internal and external callus formation
        
        chondrocytes secrete fibrocartilaginous matrix between 2 broken ends
        
        from chondrocytes in endosperm and periosteum
        
        create hyaline cartilage and bone around break
        
        cartilage replaced by trabecular bone
        
        osteogenic cells become active, divide
        
        osteoblasts adjacent to callus produce trabecular via endochondral ossification
        
        osteoclasts resorb dead bone at fracture site
        
        fracture hematoma from clotted blood within 6-8 hrs
        
        remodeling
        
        compact bone replaces trabecular/ spongy bone on outer surface of bone
        
        bump present , will be remodeled away
        
        process takes several weeks
  - - - osteoid is secreted and calcifies by osteoblasts
        
        entrapping some osteoblasts which become osteocytes
      - immature spongy bone and periosteum form
        
        osteoid secreted around capillaries: trabercula
        
        mesenchyme becomes periosteum
      - ossification center: osteoblasts cluster together
      - compact bone is formed
        
        trabecular protects it
        
        crowded blood vessels get squished around
        
        red marrow develops
      - bone develop directly from mesenchymal tissue
    - - capillaries formed from mesenchyme
        
        penetrate cartilage
      - perichondrium becomes periosteum
      - cartilage model of skeleton
        
        perichondrium forms from mesenchyme
      - secondary ossification center
        
        how bones grow in length : interstitial growth
        
        epiphyseal side: cartilage grows
        
        diaphysial side: bone grows, shaft grows in length
        
        epiphyseal plate
        
        area of hyaline cartilage in immature bone where ossification occurs
        
        ossification zone: osteoblasts secrete bone tissue on calcified cartilage
        
        calcification zone
        
        dead chondrocytes, matrix around them is calcified
        
        penetration of capillaries from diaphysis
        
        connects plate to diaphysis via cartilage stalactites
        
        hypertrophic zone
        
        chondrocytes mature, older and larger
        
        lacuna start to erode
        
        proliferative zone: chondrocytes mitosis
        
        develops at epiphyseal region
      - mesenchymal cells differentiate into chondrocytes
      - cartilage remains at growth plated articular surfaces of bone
      - bone repacking hyaline cartilage
      - primary ossification center
        
        develop deep in periosteal collar
      - periosteal collar
        
        osteoblasts make a collar of compact bone around diaphysis of cartilage model
      - chondrocytes and cartilage continue to grow at ends of bones
    - - organic components
        
        contribute to bone flexibility
        
        give bone tensile strength by resisting stretching
        
        osteoid produced by osteoblasts
        
        contains collagen protein
        
        other semisolid ground substance of proteoglycans and glycoproteins
      - inorganic components
        
        crystals deposit around collagen fibers
        
        hareden matrix, resist compression
        
        hydroxyapatite, mostly calcium phosphate
      - Proportion of inorganic and organic substances matter
        
        loss of protein( collagen)- brittle bones
        
        insufficient calcium - soft bones
        
        correct proportion- optimal functioning
  - - - interstitial growth - in length
        
        growth until early adulthood
        
        rate of growth controlled by hormones
        
        bone grows in length as osseous tissue is added to diaphysis
        
        chondrocytes in epiphyseal plate cease their proliferation
        
        bone place cartilage
        
        longitudinal growth dtops
        
        epiphyseal line remains from epiphyseal plate
      - appositional growth - in diameter
        
        osteoblasts produce new bone tissue beneath the periosteum
        
        result in
        
        new bone growth in diameter
        
        increased diameter of medullary cavity
        
        modeling: bone removed at endosteum, but being deposited on periosteum
        
        osteoclasts resorbs bone on endosteum
        
        occurs within periosteum
    - - mechanical stress
        
        results from skeletal contraction and gravitational forces
        
        required for normal bone remodeling
        
        occurs unweight -bearing movement and exercise
        
        causes increase in bine strength
      - resistance training
        
        important to slow down eventual bone loss due to aging
        
        prevent osteoporosis
      - resorption of old/damaged bone
        
        5-10% of skeleton replaced yearly
        
        influenced by hormones and mechanical stress, and injury
        
        take place on same surface where osteoblasts lay new bone to replace that which is resorbed
    - - thyroid hormone
        
        promote osteoblastic activity/synthesis of bone matrix
        
        secreted by thyroid gland
      - sex hormone: estrogen, testosterone
        
        promote osteoblastic activity/synthesis of bone matrix
        
        promotes conversion of epiphyseal plate to epiphyseal line
        
        secreted in large amount at puberty: growth spurt
      - growth hormone
        
        increase calcium retention-improving bone density
        
        increase amino acid uptake by cells
        
        indirectly stimuli cartilage growth in epiphyseal plate
      - parathyroid hormone
        
        stimulate osteoclast proliferation-
        
        promote calcium to be released in kidney tubules
        
        release stimulated by low blood calcium
    - - vitamin D
        
        converted by liver to circulating form(calcidiol)
        
        necessary for calcium and phosphate absorption
        
        kidneys transform it to usable form calcitriol D3
        
        produced by body with sunlight; added to milk and juice
      - vitamin K
        
        supports bone mineralization
        
        found in green leafy veggies
      - calcium
        
        found in diary, green leafy veggies some fish
        
        builds strong teeth and bones
      - magnesium: bone structure
      - fluoride
        
        bone structure
        
        strengthens bone and enamel of teeth
      - omega 3 fatty acids: decrease inflammation