MSK Flashcards
Approx. how many bones do you have when you are born compared to when you are an adult & why
300 when you are born but only 206 bones when you are an adult
Because bones combine to form bigger bones in the adult body
What is the inorganic/mineral bone matrix made of and what strength does it have
hydroxyapatite crystals
Compression strength
What is the organic bone matrix made of and what strength does it have
Collagen and proteoglycans
Flexible strength
What are osteochondral progenitor cells
undifferentiated stem cells
What are osteoblasts/what do they do
Lay down bone
Come from the bone marrow
only have one nucleus
Work in teams to build bone
What are osteocytes/what do they do
Mature bone cells formed in lacunae
Formed when osteoblast becomes embedded in material it has created
What is a lacunae
cavity or depression in the bone
What are osteoclasts/what do they do
Resorb (remove) bone
Absorbs bone during growth and healing
What do bone-lining cells do
regulate movement of ca2+ and PO4-
Describe cortical bone and what’s another name for it
Compact bone
Thicker than cancellous bone
And very dense
Describe what trabecular bone is and another name for it
Cancellous bone
Much lighter and less dense than cortical
What are the two types of ossification
Endochondral and intramembranous
Describe endochondral ossification
From cartilage template
ossified slowly and then turned into bone
Completed from teens to early twenties
Describe intramembranous ossification
Direct deposition of bone on thin layer of connective tissue (involved in formation of skull)
Describe appositional bone growth
Increases the bones width
osteoblast in periosteum secrete matrix and become trapped as osteocytes
osteoclasts increase diameter of medullary cavity
Continues increasing diameter until skeletal maturity
Describe endochondral bone growth
Increases the bones length
Requires interstitial growth from the cartilage first
Occurs at epiphyseal growth plate
Stops when the growth plates ossify
What is Wolffs law
States that you bones will adapt depending on the stress you put on them
What does more stress mean for bones? Less stress?
More stress means increased osteoblast activity which means more bone
Less stress means decreased osteoblast activity which means less bone
What are the five factors influencing bone growth and remodelling
mechanical factors genes hormones ageing disease
Describe how genes have an influence on bone growth/remodelling
determine their potential shape and size
Directly influences: growth hormone released, hormone receptors on bone, ability to absorb nutrients from the gut
What are the genetic disorders associated with bones
Dwarfism (achondroplasia dwarfism is same size head and trunk but shorter limbs) Turners syndrome (only affects females as it affects the X chromosome, causes short height, heart defects and failure of ovaries to develop)
How do hormones influence bone growth and remodelling
Growth, sex, thyroid hormones influence cell differentiation and metabolism
How does ageing influence bone growth and remodelling
Osteoblast matrix production slows in comparison to osteoclast matrix resorption
Decreased collagen deposition results in more brittle bones
What disease is most associated with bones
Osteoporosis
Cancellous bone mostly affected if connections lost
causes brittle bones
What are the three types of cartilage
hyaline
fibrocartilage
elastic
Where is hyaline cartilage found
at the end of long bones
What are the two ways cartilage grows
Appositional growth and interstitial growth
Explain appositional growth in cartilage
Chondroblasts
increase in diameter of bones by addition of bone tissue at the surface of bones
Explain interstitial growth in cartilage
chondrocytes
lengthening of the bone resulting from growth of cartilage and its replacement with bone tissue
What is the perichondrium
type of connective tissue that functions in the growth and repair of cartilage
Describe the outer and inner layer of the perichondrium
outer layer has dense irregular connective tissue with fibroblasts
Inner layer has fewer fibres with chondroblasts
What type of cartilage is articular cartilage
hyaline cartilage
Does articular cartilage have perichondrium
no
Describe growth in articular cartilage
Similar to growth plate
columns of cells turn into calcified cartilage which turns into bone
What is the function of articular cartilage
smooth (reduces friction, low-wear surface, reduces heat which reduces protein damage)
deformable and elastic (distributes load easily, increases surface area which decreases force)
Describe adult articular cartilage
aneural and avascular
What are three things that affect bone density
availability of substrates
biochemical factors
physiological factors
Give some examples of how availability of substrates affect bone density
Calcium intake calcium absorption (Vit D intake) Functionality of PTH (magnesium deficiency)
Give some examples of how biochemical factors affect bone density
hormones
steroid hormones, oestrogen, thyroid hormones
Give some examples of how physiological factors affect bone density
Weight bearing exercise
smoking (affects bone turnover)
BMI
healthy diet (oily fish, whole grains)
6 factors affecting fracture risk
age smoking status medication (steroids) Bone density alcohol intake previous fracture
4 functions of skeletal muscle
movement
control posture
remove (from blood) and store glucose
generate heat (temperature regulation)
what does iso mean? metric? tonic?
iso=same
metric=measure
tonic=tensions
Name 3 skeletal muscle relaxants
botulinum toxin
curare
succinylcholine
How is botulinum toxin a skeletal muscle relaxant
prevents release of Ach-containing vesicles
causes paralysis of muscles and inhibition of secretion from exocrine glands normally stimulated by parasympathetic nervous system
How is curare a skeletal muscle relaxant
blocks nAchRs (nicotinic acetylcholine receptors) to cause paralysis (used during surgery to prevent muscle spasms)
How is succinylcholine a skeletal muscle relaxant
(also known as suxemethonium)
short acting block of nAchRs (used during intubation)
What is the function of the sarcoplasmic reticulum
store calcium
release calcium rapidly (stimulated by AP)
rapidly restore calcium (using ATP driven calcium pumps)
What is the function of t tubules
to quickly convey the action potential deep inside the fibre
continuous with sarcolemma (surface membrane)
What are two membrane receptors in triads
dihydropyridine (DHP)
ryanodine receptors
what is a triad
where t tubule is surrounded by SR on both sides
Describe dihydropyridine (DHP) receptors
receptors function as voltage sensors (on t-tubule membranes)
Describe ryanodine receptors
function as calcium release channels on the sarcoplasm reticulum membrane
what do the membrane receptors in triads require for mechanism
voltage sensor in t-tubule membrane to detect AP
and a calcium release channel that is opened by the voltage sensor
What is malignant hypothermia
rare inherited condition
caused by mutation in ryanodine receptors
triggered by volatile anaesthetics
What does the axial skeleton include
skull/spine
encasing CNS
What does the appendicular skeleton include
the limbs
What are the four categories of bones
short
long
flat
irregular
What types of bones are formed from endochondral ossification
short
long
irregular
what types of bones are formed by intramembranous ossification
flat
irregular
Give an example of a short bone, long bone, flat bone and irregular bone
short=carpal bones in hand
long=humerus/femur
flat=bones in the skull
irregular=vertebrae
what is the epiphysis?
the end of the long bone
ossifies separately from the shaft/diaphysis but becomes fixed to it when full growth is attained
What is the diaphysis
the shaft of a long bone
What is the metaphysis
Wide portion near the end of long bones
where growth occurs
What is epiphysis covered in
articular cartilage
What are Haversian systems
Haversian canals surrounded by blood vessels and nerve fibres throughout the bone and communicate with osteocytes
What is 80% of skeleton weight
cortical bone
What are osteoprogenitor cells derived from
mesenchymal stem cells
What are osteoblast cells derived from
mesenchymal stem cells via osteoprogenitor cells
What do osteoblasts make
new bone matrix (type I collagen, ALP-initiates calcification, calcium phosphate)
What are osteocytes derived from
osteoblasts
What are osteoclasts derived from
monocytes
What are osteoclasts important in
breaking down and remodelling bone
How do osteoclasts bind to bone surfaces
by binding to little proteins called osteopontin
When a force is applied to bone which side is compressing and which side is under tension
the side that force is being applied to is compressing and the opposite side is under tension
What are the two types of bone healing
primary and secondary
Describe primary bone healing
needs absolute stability and compression
does not form a callous
(can get this stability using plates and screws, usually used for joints because don’t want a callous in a joint0
Needs less than 2% strain
What is a callous
bony healing tissue which forms around the end of broken bones
Describe secondary bone healing
Needs relative stability
Callous formation
(achieved by putting splint/cast on)
can have between 2-10% strain
Four stages of secondary bone healing
haematoma (inflammatory/reactive phase) soft callous (reparative phase) hard callous (reparative phase) remodelling (remodelling phase)
Describe what happens during the haematoma (inflammatory/reactive) phase of secondary bone healing
Bruising and haematoma formation solid swelling of clotted blood haematoma forms template for callous signals for cells to initiate healing (mesenchymal stem cells, osteoprogenitor cells, platelets, macrophages, neutrophils)
Describe what happens during the soft callous (reparative) phase of secondary bone healing
fibroblast cells come into area (make fibrous tissue, produce type II collagen)
new blood vessels grow through haematoma (have connective tissue and provide some stability)
fibroblasts mature into chondroblasts (make & lay down cartilage framework)
Describe what happens during the hard callous (reparative) phase of secondary bone healing
osteoblasts come in they lay down type I collagen mineralise bone (gets stiffer and harder)
Describe what happens during the remodelling phase of secondary bone healing
as bone heals people use bone more
bone will then adapt
osteoblasts come in cutting cone formation
(tipped with osteoclasts that cut through regular woven bone)
What is it called when bones do not heal
non-union
What is hypertrophic non-union
consequence of too much movement (exceeded 10% strain)
What is atrophic non-union
avascular and inert (wouldn’t heal even under correct conditions)
usually needs a bone graft
(consequence of poor bone stability and poor blood supply)
What is sarcopenia
used to describe inevitable loss of muscle mass and strength even in the healthy elderly
force and speed of contraction is reduced
What are some of the consequences of sarcopenia
loss of muscle mass loss of muscle strength increase risk falls loss of autonomy (reduced loading of skeleton from sarcopenia can result in osteopenia)
What three things is osteopenia characterised by
bone loss
reduced bone mineral density
micro-architecture deterioration
What does osteopenia mainly affect
wrist
hip
vertebrae
What happens to cortical bone with ageing
strength decreases by 2% per decade from 20 yrs
toughness decreases by 7% per decade
What happens with ageing of fibrous tissue
cell content changes
collagen cross-links increase and mature
non-enzymatic glycation makes tissue yellow and stiffer
micro damage accumulates and makes tissue weaker
cell less responsive to mechanical stimuli
What happens with ageing on cartilage
decreased proteoglycans decreased aggregation of proteoglycans increased collagen and cross-links increased non-enzymatic glycation increased apoptosis increased stiffness
What does hyaline cartilage do
its a shock absorber and load bearer
What are the features of hyaline cartilage
turgor (high water content), resilient, avascular and aneural
What is in the matrix of hyaline cartilage
glycosaminoglycans, hyalinuronic acid, chondroitin sulphate, keratan sulphate
What type of cells make up hyaline cartilage and what fibres are present
cells=chondrocytes
fibres=collagen type II
What are the four types of skeletal cells
osteoblasts
osteocytes
osteoclasts
megakaryocytes
Describe osteoblasts
make bone
synthesise osteoid and mediate mineralisation
found lined up along bone surfaces
Describe osteocytes
largely inactive osteoblasts trapped within formed bone
form well connected network via caniculi (thin protrusions)
play important role in mechanosensation
Describe osteoclasts
phagocytic cells that erode bone
important with osteoblasts in turn/over remodelling of cells
very large/multinucleate cells derived from macrophage/monocyte cell lines
found on/near bone surfaces
Describe megakaryocytes
lobulated nucleus
responsible for production of platelets
found in bone marrow
What are the four properties of muscle
elasticity
excitability (ability to respond to stimuli)
contractability
extensibility (ability to stretch without tearing)
What is epimysium (muscle connective tissue)
outside of a muscle
dense collagenous sheath
What is perimysium (muscle connective tissue)
sheath surrounding a bundle of muscle fibres
What is endomysium (muscle connective tissue)
thin connective tissue layer surrounding each myofibre
What and where is an epiphyseal growth plate
hyaline cartilage plate in the metaphysic at the end of each long bone
What is the periosteum
dense layer of vascular connective tissue enveloping bones(except at surfaces of joints)
What is the endosteum
thin vascular connective tissue that lines inner surface of bony tissue that forms the medullary cavity of long bones
What is the meniscus
piece of cartilage that provides cushion between the femur and the tibia
(two menisci in each knee joint)
What does the patella tendon attach to
to the bottom of the knee cap to the top of the shin bone (tibia)
attached to the quadriceps muscle by the quadriceps tendon
What is a synovial (joint) space
site at which articulating surfaces of bones contact eachother
What does a synovial membrane do
lines joint cavity and made up of two layers
what is intimal synovial membrane
responsible for content of synovial fluid
(1-4 cell layers thick)
(does not have a basement layer membrane)
What is subintimal synovial membrane
made up of fibrous, areolar and fatty tissues
What is adipose tissue
specialised connective tissue consisting of lipid rich cells (adipocytes)
store energy in the form of fat
What is acute pain
short duration
result of injury or disease
important protective role
What are MSK examples of acute pain
fracture
muscle sprain
acute post-operative pain
What is chronic pain
pain that lasts longer than 3-6months
can be related/unrelated to tissue damage
no useful biological function
What are MSK examples of chronic pain
chronic back pain
osteoarthritis
chronic post-operative pain
What is assessed in a pain assessment
sensory aspect of pain
physical function
emotional wellbeing/psychological aspect
role and interpersonal functioning
What is meant by sensory aspect of pain
intensity, location, frequency, quality
what is meant by physical function (in a pain assessment)
activity levels, daily life, exercise
What is meant by emotional wellbeing/psychological aspect (in a pain assessment)
pain related distress
depression
coping
what is meant by role and interpersonal functioning (in a pain assessment)
work
relationships
social activities
What are three ways to assess acute pain
verbal descriptor scales
numeric rating scales
visual analogue scales
describe a verbal descriptor scale
asking patients if there is no pain, mild pain, moderate pain or severe pain
Describe a numeric rating scale
0-10 with 10 being most severe pain
describe a visual analogue scale
ask patient to place a marker of a scale of no pain to high intensity pain
How do you assess chronic pain
brief pain inventory
What are the challenges of using a questionnaire to assess pain
pain fluctuates over time
impact of co-morbidities & pain elsewhere
adaption and avoidant strategies
what is the hierarchy of pain assessment techniques
self-report identify potential causes of pain observe patient behaviours surrogate reporting of pain attempt an analgesic trial
what is the mineral phase of bone made of
hydroxyapatite (type of calcium phosphate)
what is the organic phase of bone made of
collagen and other protein
How much calcium is moved out of the bones and into the ECF
500mmol every 24 hours
What is PTH
parathyroid hormone (produced by parathyroid gland)
What does PTH do in the kidney
Increases reabsorption of calcium in distal tubules
increases phosphate excretion
increases formation of active vit D
What does PTH do in the bone
stimulate bone resorption
breaking down into calcium and phosphate to be absorbed by the body
What is a low calcium level called
hypocalcaemia
What is the calcium receptor
CaSR
What happens if the body detects low levels of calcium
body would produce high levels of PTH to get more calcium in the body
Describe vit D3
not biologically active
formed from UV light on skin
found in oily fish
highly fat soluble (stored in adipose tissue)
Where is vit D2 found
in supplements
What happens with vit D in the liver
it is where it is first hydrolysed forms 25(OHD) =25 hydroxycholecalciferol
What bone in the wrist forms from 1-3 months
capitate
what bone in the wrist forms from 2-4 months
hamate
what bones in the wrist form from 2-4 years
triquetral
lunate
what bones in the wrist form from 4-6 years
scaphoid
trapezium
trapezoid
what bone in the wrist forms from 8-12 years
pisiform (little bone stuck on the edge of triquetral)
what are the four types of children fractures
green stick
torus (buckle)
complete
salter harris
What is rickets called in adults
osteomalacia
