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Flashcards in Muscoskeletal system Deck (20)
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What is the musculoskeletal system?

provides support and gives us ability to move
made up of
> bones (206, born with 270)
> muscles
> joints, cartilage and tendons


Axial skeleton

skull, sternum, ribs, vertebral column = balance and support


Appendicular skeleton

use to move eg arms and legs


Normal bone structure

epiphysis at top and bottom of bone
articular cartilage
spongey bone
diaphysis and medullary cavity in middle



result of trauma
treatment aim is to realign bone to allow goof function to healing
can be achieved with plaster cast +/- surgery


Fracture healing

- immediately after fracture = rupture of blood vessels = haematoma formation filling the fracture gap
- also provides a fibrin meshwork to allow formation of granulation tissue
- inflammatory cells release cytokines to activate osteoblasts and osteoclasts
- development of cartilage cap
- bone deposition begins to strengthen callous
- repair tissue reaches maximum girth 2-3 weeks
obstacles: if bone is no aligned, area not immobilised, fracture sight contains dead bone infection



decrease in bone mass and density
can lead to fractures
Imbalance between bone resorption and bone production
Inadequate peak bone mass
Excess bone resorption
Inadequate bone production


Osteoporosis risk factors

common in women due to hormonal influences (decrease in oestrogen) - post-menopause increases bone resorption and decreases new bone formation
Calcium metabolism and Vitamin D deficiency can also hinder bone formation
Drugs- steroid use


Treatment of osteoporosis

good exercise and diet (vit. D and calcium supplements)
Alendronic acid = bisphosphonate that prevents osteoclast activity
SE = heart burn



increased risk with age and obesity
usually in weight-baring joints
risk factors: increased age, female sex, pre-existing deformity, mechanical stress, genetics


Pathogenesis of osteoarthritis

'wear and tear’
breakdown of articular cartilage
underlying bone exposed
fragments of cartilage can fall into the joint
bony thickening and outgrowths (osteophytes) develop
presents as morning stiffness, pain and decreased range of movement, joint effusions


Rheumatoid arthritis

familial association
links with Human Leukocyte antigen (HLA)
inflammation in synovium = membrane thickens
cartilage and joint destruction other tissues involved eg lungs
presents as pain in small joints (hands and feet), dwelling and deformity, fever, fatigue, generalised pain, joints stiff without activity


Diagnosis of rheumatoid

need 4 of:
- Morning stiffness > 1 hour
- Arthritis in 3 or more joints
- Arthritis of typical hand joints
- Symmetric arthritis
- Rheumatoid nodules
- Serum rheumatoid factor
- Typical radiographic changes


Crystal arthropathies

Associated with intra-articular crystal formation:
> Gout
> Pseudo gout


What is gout?

Raised uric acid produced by breakdown of purine bases by enzyme xanthine oxidase
Usually excreted by kidneys, but the urate is deposited as crystals in the joints
Repeated attacks = chronic arthritis
Causes: drugs (aspirin, diuretics), alcohol, renal disease, hypothyroidism, dehydration
- sudden onset excruciating burning joint pain
- redness, warmth, tenderness, stiffness
- usually first attack involved big toe
- subsequent attacks are less severe


Pseudo gout

precipitation of calcium pyrophosphate crystals in connective tissue
crystals can enlarge and rupture
usually knees and ankles
can be hereditary
can cause sepsis


Septic arthritis

inflammation of joint due to bacterial infection
commonly affects the knee
severe pain, swelling, redness and heat
difficulty moving joint, increased temp
needs i.v antibiotics, washout of joint



bone infection caused by bacteria
due to trauma, surgery, presence of foreign bodies
diabetics at increased risk
haematogenous spread


Bone tumours

commonest bone tumour = metastatic disease from a distant cancer eg. prostate, breast, kidney
primary bone tumours are rare
> benign = osteoid osteoma
> malignant = sarcoma
red flags: fever, night pain, weight loss, history of cancer, steroid use


What are the 3 types of muscle?

Striated muscle-
skeletal muscle
voluntary movements
eg. muscular dystrophy, neuromuscular disorders
Smooth muscle -
forms muscle layer of walls in GI tract, arteries, internal organs
involuntary organs
eg. leimyomas
Cardiac muscle -
has its own pace maker