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A 12 year old boy is brought in with a bone fracture injury that he got…

- - - - Periosteum
        
        Glistening white, double layered membrane
        
        Covers external surface of the entire bone except joint surfaces
      - Endosteum
        
        Delicate connective tissue membrane
        
        Covers internal bone surfaces
    - - Proximal Epiphysis
        
        Top end of bone
      - Distal Epiphysis
        
        Bottom end of bone
      - Outer shell of compact bone forms the epyphysis exterior
      - Interior is spongy bone
      - Thin layer of hyaline cartilage covers joint ends of each epiphysis, cushioning each end
      - Epiphyseal Line
        
        Between the diaphysis and each epiphysis of an adult long bone
        
        Remnant of the epiphyseal plate
      - Epiphyseal Plate
        
        AKA Growth plate
        
        Disc of hyaline cartilage that grows during childhood to lengthen the bone
      - Metaphysis
        
        Flared portion of the bone where the diaphysis and epiphysis meets, whether it is an epiphysial plate or line
    - - Nutrient Foramen
        
        Hole in the wall of diaphysis for arteries and veins to run through
        
        Nerves accompany vessels into the bone
      - Nutrient Vein
        
        Branches to supply compact bone
      - Nutrient Artery
        
        Runs inward to supply bone marrow and spongy bone
    - - Collar
        
        Compact bone that surrounds the medullary cavity
      - Medullary Cavity
        
        AKA Marrow Cavity
        
        Contains no bone tissue
        
        Contains yellow marrow
        
        Between marrow and compact bone, there is often a layer of spongy bone
    - - Bone Tissue
        
        Osteocytes
        
        Mature bone cells that occupy spaces that conform to their shape
        
        Act as stress or strain sensors and respond to mechanical stimuli
        
        Bone lining cells
        
        Flat cells found on bone surfaces where bone remodeling is not going on
        
        Thought to help maintain the matrix
        
        Osteoblasts
        
        Bone forming cells that secrete the bone matrix
        
        Responsible for bone growth
        
        Osteoclasts
        
        Giant multinucleate cells located at sites of bone resorption
        
        Bone eaters
        
        Osteoprogenitor Cells
        
        Mitotically active stem cells
      - Compact Bone
        
        Canals and Canaliculi
        
        Central Canal
        
        Runs through the core of the osteon
        
        Contain small blood vessels and nerve fibers that serve the osteon's cells
        
        Perforating Canal
        
        Lie at right angles to the long axis of the bone
        
        Connect the blood and nerve supply of the medullary cavity to the central canals
        
        Lacunae
        
        Hold osteocytes
        
        Hollow holes at junctions of lamellae
        
        Canaliculil
        
        Hairlike canals radiating from lacunae
        
        Connect lacunae to one another
        
        Lamellae
        
        Interstitial
        
        Lay between intact osteons
        
        Either fill gaps between forming osteons or are remnants of ones lost during bone remodelling
        
        Circumferential
        
        Located deep to the periosteum and superficial to the endosteum extend around the circumfrance of the diaphysis
        
        Effectively resist twisting of the long bone
        
        Osteon
        
        Structural unit of compact bone
      - Spongy Bone
        
        Trabeculae align precisely alone lines of stress and help the bone resist it
    - - Red
        
        AKA myleoid tissue
        
        Where red blood cells, white blood cells and platelets are formed
      - Yellow
        
        Some white blood cells are developed here
        
        Storage of fats in adipocytes
        
        Also contains mesenchymal (connective) stem cells
  - - - Length
        
        Hypertrophic Zone
        
        Older chondrocytes in the stack, closer to the diaphysis, get bigger
        
        Lacunae erode and grow leaving large interconnected spaces
        
        Calcification Zone
        
        Surrounding cartilage matrix calcifies, chondrocytes die, matrix deteriorates, blood vessels invade
        
        Long slender spicules of calcified cartilage remain at epiphysis and diaphysis junctions
        
        Proliferation Zone
        
        Cells at the "top" stack to create this area
        
        Cells divide quickly, pushing epiphysis away from diaphysis and lengthening the whole long bone
        
        Ossification Zone
        
        Calcified spicules invaded by marrow from medullary cavity
        
        Osteoclasts partly erode spicules and osteoblasts cover them with new bone
        
        Spongy bone replaces them, osteoclasts digest spicule tips and medullary cavity lengthens
      - Thickness
        
        Bones widen as they thicken
        
        Increase in thickness/diameter by appositional growth
        
        Osteoblasts in periosteum secrete bone matrix on bone surface as osteoclasts on endosteal surface remove bone
        
        Normally more building up than broken down
        
        Creates thicker, stronger bone, but prevents excessive weight
    - - Resorption
        
        Osteoclasts move along bone surface, digging grooves as they break down the matrix
        
        Border of osteoclast clings to the bone and seals it off, secreting acid at the site of damage to dissolve minerals
        
        Lysosomal enzymes digest the matrix
        
        Digested materials are transported across the osteoclast and released on the opposite side
        
        Interstitial fluid --> blood
        
        Upon resorptions completion, the osteoclasts die of apoptosis
      - Deposition
        
        Following osteoclasts, osteoBLASTS start laying down new bone matrix
        
        Begins at the osteoid seam
        
        Between osteoid seam and older mineralized bone there is an abrupt transition called the calcification front
        
        Calcium salts are deposited throughout the osteoid, creating calcified bone matrix
    - - Endochondral Ossification
        
        Cartilage calcifies in the center of the diaphysis and then develops cavities
        
        Periosteal bud invades the internal cavities and spongy bone forms
        
        Bone collar forms around diaphysis of the hyaline cartilage model
        
        Diaphysis elongates and a medullary cavity forms
        
        Epiphyses ossify
  - - - New blood vessels begin to grow into the clot
      - Broken ends are connected with repair tissue or soft callus, splinting the broken bone
    - - Replaces fibrocartilaginous callus
      - Formation of hard callus continues until a firm union forms two months later
      - Generally repeats the events of endochondral ossification
    - - Blood vessels in bone and perosteum are torn
      - Blood clots forming hematoma
      - Swollen, painful inflammed tissue
    - - Compact bone is laid down to reconstruct shaft walls
      - Bone is generally stronger, yet similar to original bone that was broken
    - - Realignment of the broken bone ends
  - - - Complete
        
        If bone is broken through
      - Incomplete
        
        If bone is not broken through
    - - Open (compound)
        
        Bone has broken through the skin
      - Closed (simple) fracture
        
        Bone has not broken through the skin
    - - Nondisplaced
        
        Bone ends retain normal position
      - Displaced
        
        Bone ends are out of normal alignment
    - - Spiral
        
        Ragged break occurs when excessive twisting forces are applied to a bone
        
        Common sports fracture/possible sign of abuse in children
      - Epiphyseal
        
        Epiphysis seperates from the diaphysis alone the epiphyseal plate
        
        Tends to occur where cartilage cells are dying and calcification of matrices are occuring
      - Compression
        
        Bone is crushed
        
        Common in porous bones subjected to extreme trauma
      - Depressed
        
        Broken bone portion is pressed inward
        
        Typical of skull fracture
      - Comminuted
        
        Bone fragments into three or more pieces
        
        Common in elderly with more brittle bones
      - Greenstick
        
        Bone breaks incompletely, only one side of the shaft breaks, opposite side bends
        
        Common in children whose bones have relatively more organic matrices and are more flexible than adult bones