R2 LOCO1 Flashcards
Describe happens when muscle fibres become deinnervated [1]
All muscle fibres innervated by a damaged motor unit undergo atrophy
Damaged: arrow
Describe what a target fibre is [1]
Why does a target fibre arise? [1]
Describe the apperance [1]
When a damaged muscle is re-innervated; nuclei of muscle moves centrally and causes the production of new actin and myosin fibres
Occurs due to satellite cells differentiating and proliferating
Which are the slow & fast fibres in this stain? [2]
Slow fibres (Type 1): more mitochondria - darker stain
Fast fibres (Type 2): less mitochondria - light stain
Describe the pathophysiology of sarcopenia
- 0.5 - 1% of muscle mass is lost each year after age of 50; 3-5% if inactive
- Muscle replaced with fat
- No difference in men and women
- Causes an increase likelihood of fractures
- Impaired balance
Which muscle fibres degenerate more in sarcopenia? [1]
Generally, a significant decline of type II, but not type I muscle fibers are observed in sarcopenic patients
How does an EMG present with patients who have myopathy?
Compared to healthy and neuropathy patients [2]
In myopathic motor units, the number of functional muscle fibers is reduced. Therefore motor unit action potentials (MUAPs) are smaller in amplitude and duration. Because of the asynchronous firing of affected muscle fibers, the morphology of MUAPs become polyphasic.
How does a patient with dermatoymositis present? [4]
Rash around eyes
Peri-orbital oedema
V sign of neck due to increased photosynsetivity
Gottron’s sign
How does a biospy from a patient with polymyositis / dermatomyositis present? [1]
- (some have subclinical muscle involvement)
- Muscle generally not involved; CD8 T cells cells infiltrate the periphery of the muscle fasicle
- Central nuclei
- Variation in fibre size
Describe the effect of CD8 infiltration in dermatomyositis [1]
CD8 T cells bind to MHC 1 to create: CD8-MHC1 complex
Describe the change that occurs in subcutaneous calcifications [3]
Dermis-epidermal junction: vacuoles develop, mucin deposite and calcifications
Describe treatment regime of dermatomyositis [4]
Prednisilone (type of corticosteroid):
* 1 mg / kg per day until creatine kinase normal
Azthioprine
Methotrexate
Rituximab
Which muscular dystrophies are the most common? [2]
Describe their inheritance [1]
Duchenne & Becke Muscular Dystrophies;
X-linked - recessive
Describe pathophysiology of Duchenne MD [2]
Which serum marker is raised in DMD? [1]
Healthy muscle: dystrophin is a ring around muscle fibre that connects the ECM to contractile apparatus so that endomesium moves with muscle
Duchenne: no muscle fibres with dystrophin; causes elevated creatine kinase
Which muscle groups are most at risk in Duchenne MD? [2]
What does this mean clinically? [2]
Respiratory muscles & diaphragm; die from resp. failure
Dilated cardiomyopathy occurs; heart failure
How does early DMD appear histologically? [3]
Fibre size variation
endomysial & perimysium fibrosis
Degenerating muscle fibres undergoing myophagocytosis
How does late DMD appear histologically? [2]
Loss of muscle; atrophy of fibres and death - replaced with fibrotic material and fat
Treatment for DMD? [2]
Prednisilone
Gene alterations
How do statins affect 10% muscle? [2]
Rhabdomyolysis; get vacuoles in type 2 muscle fibres
Name and describe how two therapeutic drugs cause myopathy [2]
Corticosteroids; cause dose dependent type 2 atrophy
Hydroxychloroquine: not dose dependent atrophy; lysosomes damaged
Hydroxychloroquine causing lysosome damage
Which tissue is affected in fibromyalgia? [1]
Which muscles are painful? [1]
Which antibodies are present in 50% of patients? [1]
Connective tissue damaged; causes widespread pain in both sides and above & below waist axial skeleton pain
Antipolymer antibodies
How do you diagnose fibromyalgia? [1]
Apply 2kg of pressure on 18 specific tender points in the body; 11/18 is a positive diagnosis
Treatment options for fibromyalgia? [4]
Amitriptyline (TCA)
Fluxetine (SSRI)
Exercise
Complementary therapy
Give three pieces of evidence that RA is autoimmune disease [3]
1- Patients produce auto-antibodies (in blood and joints).
2- Inflamed joints are filled with activated immune cells, cytokines
3- Joint conditions are strongly associated with MHC genes, required for T cell activation.
What is the role of MHC class molecules? [3]
- MHC determines which peptides are presented to T-lymphocytes.
- MHC molecules determines T-lymphocyte tolerance in the thymus (i.e. what mature T cells enter the periphery / survive) and also determines if and how mature T lymphocytes respond to antigens upon encounter.
Therefore: any strongly recognised self-T cells are killed off
Which vertebrae have a downward-sloping spinous process
Cervical
Thoracic
Lumbar
Sacral
Thoracic
Which vertebrae have a small vertebral foramen
Cervical
Thoracic
Lumbar
Sacral
Thoracic
What is a Jefferson Fracture? [1]
bone fracture of the vertebra C1
What is Hangman’s fracture? [1]
fracture which involves the pars interarticularis of C2 on both sides, and is a result of hyperextension and distraction.
Correct! A Jefferson fracture is a burst fracture of the atlas, usually the result of axial loading injurues like diving headfirst into shallow water. This one is an example of a four-part fracture
Describe a wedge fracture [1]
Wedge fracture:
This fracture usually occurs in the front of the vertebra, collapsing the bone in the front of the spine and leaving the back of the same bone unchanged, which results in the vertebra taking on a wedge shape.
Pectoralis major and latissimus dorsi are both adductors of the shoulder, and they attach to the proximal humerus. Normally, the clavicle holds the arm laterally away from the body, but this fracture causes it to collapse. The humerus is pulled medially, dragging the lateral fragment of clavicle with it.
On the MRI below, a tendon passing deep to the acromion appears thickened and abnormally bright. To which muscle does this tendon belong? [1]
Acceptable responses: supraspinatus
Which structure(s) is (are) most at risk in the injury below? Select all that apply.
Describe what a Colles fracture is [1]
Colles fracture
* extra-articular (not involving the joint) fracture of the distal radius with dorsal angulation and impaction.
Describe what a Smith fracture looks like [2]
extra-articular fracture of the distal radius with volar (anterior) angulation and impaction.
What type of pelvic fracture causes bladder damage? [1]
Diastasis (seperation) of the pubic symphysis
What type of fracture causes superior gluteal nerve damage? [1]
sacroiliac joint disruption
How can you classify intracapsular neck of femur fractures? [3]
How can you classify extracapsular neck of femur fractures? [2]
Intracapsular fractures include subcapital, transcervical and basicervical.
Extracapsular fractures include intertrochanteric and subtrochanteric.
Which type of fracture is shown
subcapital
transcervical
basicervical
subtrochanteric
intertrochanteric
intertrochanteric fracture
Common extracapsular fractures of the proximal femur at the level of the greater and lesser trochanter
Which type of fracture is shown
subcapital
transcervical
basicervical
subtrochanteric
intertrochanteric
Basicervical fracture. There is a fracture at the base of the neck of the right femur, just proximal to the trochanters (white arrows). There is varus deformity (white line) of the femoral shaft.
Which type of fracture is shown
subcapital
transcervical
basicervical
subtrochanteric
intertrochanteric
Comminuted intertrochanteric fracture. There is a fracture from the greater to the
lesser trochanter (blue arrow). There are separate fragments of the greater trochanter (white arrow) and lesser trochanter (red arrow). There is varus deformity (white line) of the femoral shaft.
Which type of fracture is shown
subcapital
transcervical
basicervical
subtrochanteric
intertrochanteric
Sub-capital hip fracture. On the frontal view, there is a step-off in the cortex superiorly (red arrow) while there is abnormal overlapping of the femoral head and neck (white arrows) due to impaction. On the lateral view, the same step-off can be seen (red arrow) as well as the impaction (white arrow).
How does local acupuncture work? [4]
Stimulates nerve fibres in skin and muscle
Vasodilation / Blood vessel proliferation
Nerve growth
Acupuncture promotes local healing
