Biomechanics of Skeletal Tissue Flashcards
Bones are generally made of…
calcium carbonate
What percentage of calcium phosphate are bones made up of?
60-70% of bone weight
Calcium phosphate functions to…
create stiffness of the bone and protect against compression
What minerals aid in bone growth
magnesium, sodium, and fluoride; collagen also helps with flexibility
Waters function in bone is to..
transports nutrients and remove waste
characteristics of Cortical Bone
decreased bone porosity; stiffer/ not very deformable
Where can cortical bone be found?
shafts of longs bones or outer surface of flat bones
characteristics of Trabecular Bone
increased porosity; deforms easier
Other terms for trabecular bones are…
cancellous/ spongy bone
Trabecular bone can be found…
at the end of long bones
Trabecular bone functions to…
absorb impact/ pressure/ and compression
What is the periosteum?
the membrane surrounding bone
The periosteum functions to…
protect the bone
anisotropic in reference to collagen fibers means…
different mechanical properties in response to stress from different directions
Which force is bone most designed to handle?
compression
Which force is bone weakest under?
shear
Short bones mostly function to…
absorb shock and decrease shear force on long bones
Flat bones function to…
distribute force across bone area to lessen impact
What are examples of short bones?
tarsals and carpals
What are some examples of flat bones?
scapula, sternum, ribs, and skull
Why are
“irregular” bones irregular?
because they have many process for muscles and ligaments to attach to
What are some examples of irregular bones?
vertebrae and sacrum
What are some examples of long bones?
tibia, fibula, femur, humerus, ulna, and radius
Long bones function to…
hold body weight. lever system for movement
Longitudinal growth occurs at the…
epiphysis of the epiphyseal plate
Where do new bones cells form?
in cartilaginous discs
cartilaginous discs are located…
at the end of long bones
When are cartilaginous discs most active?
between 12-15 years old
Cartilaginous discs typically close around…
age 18 years old; 25 years old for hip
A fracture that spreads to the inside of a growth plate is called…
a Salter-Harris fracture
Osteoblasts function to…
build bone in the periosteum
osteoclasts function to…
reabsorb and clean out the medullary cavity
a larger cavity in the bone provides more…
torsional support
Bone modeling results in…
bone size and shape; modeling rate decreases after skeletal maturity
Bone remodeling results in…
fine tuning of bones; 5-25% per year
Bone remodeling functions to…
provide added strength to bones and removes fatigued/ damaged bone
These sense changes in fluid through pores within bone…
osteocytes
Blastic activity is caused by what?
osteocytes
Bone mineral density parallels…
stress to the bone
Tennis players tend to have larger…
radius
Baseball players tend to have larger…
dominant humerus
Athletes competing in impact sports have higher…
bone densities than swimmers/ non-impact
Why do children have more pliable bones?
because they have large amounts of collagen in their bones
What happens to bone brittleness as we age? Why?
bone brittleness increases due to loss of collagen
Bone mineralizes until…
women: 25-28
men: 30-35
At what rate doe women lose bone density and volume per year?
.5-1% per year until menopause
Women can lose up to what percentage of bone density/ volume per year?
4% per year
A lack of stress causes… in bone density?
bone atrophy; a decrease in bone mineral density
A progressive resistance program aids to…
decrease the rate of bone mineral reduction
Female Athlete Triad
- disordered eating
- amenorrhea/ no period
- bone mineral loss
Eating disorders effect…
hypothalamus activity; gonadotropin releasing hormone
eating disorder results in…
decreased release of luteinizing hormone in the ovary
What percentage of female athletes are affected by eating disorders?
22% cheerleaders
69% dancers
65% long-distance runners
Cessation of menstrual cycle leads to…
estrogen deficiency
Estrogen deficiency leads to…
increased bone reabsorption; osteoclastic activity
Female Athlete Triad can lead to what percentage of decreased bone mineral density?
10-20% decrease
Female Athlete Triad predominantly affects which bones?
weight bearing bones; tibia, femur, vertebrae
A bone densitometry (DEXA) scan is to…
assess bone density
Stress fractures are caused by…
low magnitude forces repeatedly sustained
Examples of low magnitude forces are…
- bending
- impact
- compression
Stress fractures start…
in the periosteum and then into the cortical bone
Most stress fractures are located in the…
tibia
What are some causes of stress fractures?
- increased training intensity/ duration
- not absorbing forces correctly
- changes in running surface
- osteoblasts can’t maintain with osteoclast activity
