Muscoskeletal system

Question 1

What is the musculoskeletal system?

Answer 1

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

Question 2

Axial skeleton

Answer 2

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

Question 3

Appendicular skeleton

Answer 3

use to move eg arms and legs

Question 4

Normal bone structure

Answer 4

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

Question 5

Fractures

Answer 5

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

Question 6

Fracture healing

Answer 6

• 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

Question 7

Osteoporosis

Answer 7

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

Question 8

Osteoporosis risk factors

Answer 8

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

Question 9

Treatment of osteoporosis

Answer 9

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

Question 10

Osteoarthritis

Answer 10

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

Question 11

Pathogenesis of osteoarthritis

Answer 11

‘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

Question 12

Rheumatoid arthritis

Answer 12

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

Question 13

Diagnosis of rheumatoid

Answer 13

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

Question 14

Crystal arthropathies

Answer 14

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

Question 15

What is gout?

Answer 15

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
Features:
- sudden onset excruciating burning joint pain
- redness, warmth, tenderness, stiffness
- usually first attack involved big toe
- subsequent attacks are less severe

Question 16

Pseudo gout

Answer 16

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

Question 17

Septic arthritis

Answer 17

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

Question 18

Osteomyelitis

Answer 18

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

Question 19

Bone tumours

Answer 19

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

Question 20

What are the 3 types of muscle?

Answer 20

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