MSK

Question 1

What is myotonia congenita?

What are its aggravating and relieving factors?

Answer 1

Myotonia = inability to relax muscles at will

• Caused by mutation in chloride channels - can be recessive or dominant
• Leads to muscle stiffness, particularly in legs - may be enhanced by cold and inactivity and often relieved by exercise

Question 2

What is syndactyly?

Answer 2

Fusion of digits

Question 3

What is polydactyly?

Answer 3

Extra digits (genetic recessive trait)

Question 4

What is the name for the complete absence of a limb?

Answer 4

Amelia

Question 5

What is meromelia?

Answer 5

Partial absence of one or more limb structures e.g. A humerus

Question 6

What is phocomelia?

Answer 6

A type of meromelia whereby hands and feet are attached directly to trunk

Question 7

Define malformation

Answer 7

Intrinsic error in coordination of morphogenetic - things don’t form correctly

Question 8

Define deformation

Answer 8

A formed limb or digit is cut off by constriction bands - strands of amniotic tissue

No genetic abnormality

Question 9

Define disruption (in context of morphogenesis)

Answer 9

Caused by an external agent e.g. Thalidomide, or viruses such as rubella and herpes

Disrupts AER so stops elongation of the limbs

Question 10

What are the four stages of disk herniation?

Answer 10

1. Disc degeneration = This is chemical changes which occur with aging – causes disc to weaken but without herniation.
2. Prolapse = Protrusion of nucleus pulpous with slight impingement of spinal canal.
3. Extrusion = Nucleus pulpous breaks through annulus fibrosus but does not leave disc space.
4. Sequestration = Nucleus pulpous breaks through annulus fibrosus and lies outside of disc space, in the spinal canal.

Question 11

What is cervical spondylosis? What does it result in?

Answer 11

Effectively arthritis of the cervical spine

• NARROWER DISCS (age –> loss of water and pressure) - osteophytes form at front and back to bear weight
• Pressure on nerve roots –> RADICULOPATHY
  Dermatomal paraesthesia and pain, motor weakness
• MYELOPATHY - Pressure on cord (rare)
  Leads to global weakness, gait dysfunction, loss of balance, loss of bladder and bowel control

Question 12

What is a C1 (atlas) fracture called?
What can it be caused by?
What does it result in?

Answer 12

JEFFERSON’S FRACTURE

• Fracture of anterior and posterior arches
• Caused by axial load e.g. Diving into shallow water, impact against roof of vehicle
• Typically caused by pain but no neurological signs - vertebral foramen is so big
• BUT may damage arteries at the base of the skull with secondary neurological consequences e.g. Ataxia (loss of coordination)

Question 13

What is a fracture of C2 (axis) called?
What causes it?
What can it lead to?

Answer 13

HANGMAN’S FRACTURE

• Fractures through pars interarticularis
• Caused by hyperextension of head or neck
• Unstable fracture –> displacement of C1 and body of C2 on C3 - can transact SPINAL CORD

Question 14

What causes a fracture of the odontoid process?

What imaging technique would you use to confirm?

Answer 14

FLEXION - blow to the back of the head e.g. Falling back against a wall
HYPEREXTENSION - old person falling forward and hitting chil/forehead (will also see bruising of face)

Would use AP x-ray or MRI

Question 15

What is whiplash? What can it lead to in serious cases?

Answer 15

Hyperextension followed by hyperflexion

C spine is very mobile so can lead to cord injury

Question 16

What is neurogenic claudication?

Answer 16

Pain upon walking due to stenosis of foramina where nerve roots exit spine - narrowing around nerve roots

Question 17

What is spondylolysis?

Why is spondylolysthesis?

Answer 17

Fracture in pars interarticularis

Movement of one vertebra relative to the ones above/below it (caused by spondylolysis)

Question 18

Describe the anatomical abnormality in the bones in spina bifida occulta.

What is meningocele spina bifida?

Answer 18

Laminae of lower lumbar vertebrae and upper sacral vertebrae fail to fuse completely.

‘Occulta’ because no resulting disability so often never detected

Meningocele: Meninges protrude through cleft in vertebrae.
Spinal fluid often fills these protrusions causing cysts - can often be removed by can still result in some spinal cord damage - weakness to lower limbs, faecal and urinary incontinence

Question 19

At what level do you do a lumbar puncture? What structures must the needle pass through to reach the subarachnoid space?

Answer 19

L3/4 or L4/5

Skin, subcutaneous fat
Supraspinous ligament, interspinous ligament, ligamentum flavum,
Epidural space, dura, subdural space, and arachnoid.