bone Flashcards
function of the skeleton
shape and support, protection, movement, blood cell production, mineral storage
axial skeleton
central, skull, spinal cord and ribcage
appendicular skeleton
external to central skeleton
eg long bones
femur
what does long bones contain?
bone marrow
eg short bones
carpals
short bones
no central cavity
eg flat bones
pelvis
eg irregular bones
vertebrae
sutural bones
specific to the skull, bind together through growth
sesamoid bones
embedded within connective tissue
eg sesamoid bone
patella
epiphysis
end of the bone, spongy bone inner
metaphysics
regain where diaphysis meets the epiphysis
diaphysis
middle region bone
medullary cavity
inner region of the diaphysis
- yellow bone marrow (adults)
- red bone marrow (children)
epiphyseal line
across the growth plate, region where bone growth terminates in adolescence
periosteum
double layer membrane around outside of bone
contains conective tissue, osteoblasts, osteoclasts and osteoprogenitor cells
endosteum
layer around inner surfaces that contain osteogenic layer
Osteoid
organic matrix and small amounts of magnesium, sodium and bicarbonate
importance of collagen in bone
provides a bit of flexibility so the bone can withstand stress
importance of mineral in bone
provides strength and support
cortical bone
encases the spongy bone, the thick outer surface of typically a long bone that encases the medullary cavity
roles of trabecular bone
- load dissipation, spreads it across to reduce tension
- resists compression
remodelling
bone is regenerating all the time
osteoblasts
bone formation, found in growing portions of bone such as periosteum and endosteum
osteocytes
sense mechanical strain, found in the matrix
osteoclasts
bone resorption, found in bone surfaces and at sites of old, injured unneeded bone
wolff’s law
bone adapts to loads under which it is placed
Process of bone formation
Response to increased stress, osteoblasts dominate and make bone stronger
Process of bone resorption
Response to decrease stress, osteoclasts dominate and bones become weaker
Process of bone modelling
Activation, resorption, reversal, formation, termination
Activation of bone modelling
Hormonal or mechanical stimulation detected by osteocytes
Resorption of bone modelling
Osteoclasts release acid and enzymes to break down bone,creating “howships lacunae”
Howships lacunae
Where bone has been broken down and ready for growth
Reversal of bone remodelling
Osteoclasts die, osteoclasts precursors enter the lacunae
Formation of bone modelling
Osteoclasts generate new osteoid
Termination of bone modelling
Some osteoblasts die and the rest become osteocytes. The osteoid undergoes calcification
Coupling
A balance between formation and resorption
Factors contributing to bone loss
- reduced activity
- change in nutrient absorption
- reduced sunlight
- loss of vitamin D
When is peak bone mass achieved
25
Bone development
- Skeleton starts as a cartilage model in the womb
- as it grows the cartilage becomes calcified
- blood vessels grow bringing nutrients & oxygen, osteoblasts convert the calcified matrix to spongy bone
- osteoclasts breakdown newly formed bone creating the medullary cavity
- new ossification centre develops at the epiphysis
Process of fracture repair
- haematoma
- soft callus
- hard callus
- remodelling
Process of haematoma in fracture repair
Blood clot formation, followed by a period of inflammation
Soft callus in fracture repair
Capillaries grow into the haematoma and there is an influx of phagocytes to remove dead tissue
Hard callus in fracture repair
Fibrocartilage is slowly converted to harder spongy bone by osteoblasts
Remodelling in fracture repair
Excess material around the diaphysis is removed
What colour does bone appear on radiographs
White
Transverse fracture
Straight across the bone
Oblique fracture
Greater than 30 degree angle - diagonal
Spiral fracture
Spiral pattern through the bone
Impacted fracture
Bone ends driven into one another
Greenstick fracture
Incomplete fracture through one side of cortex
Avulsion fracture
Part of bone is “pulled off” by ligament
Depressed fracture
Depression of cortex in flat bones
What mechanism of injury would cause a fractured base of 5th metatarsal
Inversion
Clinical significance of callus formation
Haven’t came in time of injury, safeguarding issue
What are the potential complications of fractures
Nerve damage, blood supply problems, ligament disruption, development of arthritis, infection, compartment syndrome
Treatment of fractures
Closed manipulation, open reduction and external fixation
What is the difference between a dislocation and a subluxation?
Dislocation: complete separation of joint surfaces
Subluxation: partial separation of joint surfaces
osteoporosis
decreased bone mass
osteoporosis
abnormal dense bones
osteogenesis imperfecta
abnormal bone remodelling
Paget’s disease
abnormal bone remodelling
pathological lesions
abnormal changes in tissues or organs due to disease or injury
bone cysts
fluid filled sacs
osteomyelitis
bone infection
avascular necrosis
death of bone cells, lack of circulation
what 2 bones of the body are probe to avascular necrosis when fractured?
head of femur, scaphoid
growth plate fractures
fractures that occur in the epiphysis or growth plates of childrens bones
ossification of carpal bones
- capitate and hamate: 1st year of life
- triquetrum : 3rd year
- lunate: 4th
- scaphoid: 5th
- trapezium and trapezoid: 6th
- pisiform: 12th
