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A 12 year old boy with a bone fracture injury (Background information…
A 12 year old boy with a bone fracture injury
Upstream causes
Indirect cause
The boy bones are weak because he does not have enough calcium and nutrients
Direct Cause
The boy fell forward directly on the forearm while running and broke his right arm
Downstream effects
The broken area is basically the distal humerus, the area above the elbow
The 12 year old boy does not have enough calcium and has lack of good nutrition, that is why fracture was likely to occur
It will heal quickly as the fractures in children heal faster as compared to aged people
Background information
Anatomy of long bones
Microscopic Anatomy
Cells of bone tissue
Osteoblasts
Immature cells, form bones and secrete bone matrix called osteoid
Osteocytes
Mature cells in lacunae, maintain bone matrix
Osteogenic cells
Active stem cells in periosteum and endosteum membranes which gives growth to bones
Osteoclasts
Resorption of bone (break down)
Compact bone
Canals and Canaliculi
Lacunae
Small cavities that contain osteocytes
Canaliculi
Hair like canals that connect lacunae to each other and central canal
Perforating Canals
Lies at the right angle of central canal that connect blood vessels to nerves of periosteum, medullary cavity and central canal
Central Canal
Runs through core of osteon that contains blood vessels and nerve fibers
Interstitial lamellae
It is not the part of osteon but fill gaps between the forming osteons
Osteon
Lamellae contains collagen fibers that run in different direction in surrounding rings
An osteon cylinder that has a several rings of bone called lamellae
A structural unit of compact bone consist of a long cylinder that runs parallel to long axis
Circumferential lamellae
Lies deep at periosteum and superficial to endosteum, help resist twisting in long bones
Spongy bone
Appears poorly organised but is actually organised, has stress lines that resist stress in bones
Osteons are not present but trabeculae irregularly contains lamellae and osteocytes connected to canaliculi
Capillaries in endosteum supply nutrients
Chemical Anatomy
Organic components
Allow resist tension
Osteoid
Organic part of Matrix and secreted by osteoblasts that consists of collagen fibers and ground substances
Inorganic components
Allow resist Compression
Hydroxyapatities
They are mineral salts, make 65% of bone by mass and mainly consists of calcium phosphate crystals in and out collagen fibers
Gross Anatomy
Compact Bone
Dense outer of cells that appears to be solid and smooth
Compact bone Sandwich between two Connective tissue membranes
Periosteum
White doubled layer membrane that covers external area of bone except joints
Fibrous layer
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Osteogenic layer
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Endosteum
Delicate membrane covers internal area of bone
Spongy Bone
Made up of honeycomb small flat pieces of bones called trabeculae
Diaphysis (shaft)
Forms long axis of bone and consist of compact bone surrounding central medullary cavity
Between epiphyses and diaphysis is the
epiphyseal plate
A plate where bone growth takes place
Epiphyses (bone ends)
consists of compact bone externally and spongy bone internally
Tissue in bone
Hematopoietic tissue (blood forming)
Red bone marrow ( in newborns and adults)
Bone markings
Surfaces that form joint
Passageway for blood vessels and nerves
Attachment of ligaments and muscles
Bone formation, growth and remodeling
Bone growth
Growth of long bones in length
Long bones grow in length by interstitial growth of epiphyseal plate, bone length ceases around 18 years in female and 21 in males
Growth of long bones in width
Bones grow wide through appositional growth, occur throughout life and bones gets thick when stress increases
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Harmonal regulation of bone growth
Growth hormone
Important hormone increase epiphyseal plate activity in infants and childhood
Thyroid hormone
Controls the activity of growth hormone
Sex hormones
Promotes the adolescent growth, the growth ends when epiphyseal plate closes.
Testosterone hormones in males and Estrogens in females
Bone remodeling
Bone deposit
It is function of osteoblasts, this process requires Vitamin D that enhances calcium absorption and Vitamin C is needed for collagen formation
Calcium and phosphate is needed for calcification
Bone resorption
It is the function of osteoclasts, secretion of lysosomal enzymes and protons that digest Matrix which releases into fluid and blood
Control of remodeling
Hormonal Control
Determines when the remodeling occurs in response to changing levels of blood calcium
Mechanical stress Control
It determines where the stress occurs
Formation of bone
Endochondral ossification
Formation of bone by the replacement of hyaline cartilage, forms most of skeleton, these bones are called endochondral bones
Intramembranous Ossification
Development of bone from fibrous membrane, formation of cranial bones of skull and clavicle bones, these bones are called membranous bones
Stages of Bone Healing
Fibrocartilaginous Callus Formation
Create cartilage matrix of repair tissue and osteoblasts form spongy bone in the matrix, this mass of repair tissue is known as fibrocartilaginous callus
Bony Callus Formation
Bony callus is formed the conversion of callus into hard callus of spongy bone
Hematoma Formation
Tear blood vessels and forms mass of clotted blood called Hematoma
Bone Remodeling
Osteoclasts remove excessive bony callus and compact bone reconstruct shaft walls and final structure is same as original because of the same mechanical stress
Classification Of Fractures
Completeness of break
Complete
Broken throughout
Incomplete
Not broken throughout
Penetrated skin
Compound
Skin is penetrated
Simple
Skin is not penetrated
Position of bones
Displaced
Ends keep normal position
Nondisplaced
Ends are not in normal alignment
Epiphyseal plate
Location
It is located between the diaphysis (shaft) and epiphysis (bone ends)
Function
A plate where the growth of bone takes place
Minerals for bone growth and repair
Bone growth and repair requires constant supply of nutrients and minerals
Phosphorous
Protein
Potassium
Vitamin D
Calcium (most important)