Disorders of motor units

Question 1

Myopathy

Answer 1

• disorders of skeletal muscles
• Muscle weakness
• Causes proximal limb weakness or fatigue

Question 2

Amytrophic lateral sclerosis

Answer 2

• disease cause death of neurons that control voluntary muscles
• wasting of arm muscles/ leg weakness

Question 3

Myasthenia gravis

Answer 3

autoimmune disease caused by antibodies targeted against acetylcholine receptors
leads to degredation of receptors and damages post synaptic membrane

Question 4

Foot drop

Answer 4

• Inability to raise the front part of the foot due to weakness/paralysis of tibialis anterior that lifts the foot

• peripheral nerve lesion or nerve root lesion
• Injury to peroneal nerve which is susceptible to injury, and dorsiflexes the foot
• L4 - S2 - nerve root gives rise to sciatic nerve
• Sciatic nerve split into tibial nerve and common perioneal nerve above the knee
• common peroneal nerve runs anteriorly and innervates tibialis anterior

Question 5

Myelopathy

Answer 5

spinal chord damage

Question 6

Cervical spondolysis

Answer 6

• Cervical spondylosis is a chronic degenerative condition of the cervical spine that affects the vertebral bodies and intervertebral disks of the neck (in the form of, for example, disk herniation and spur formation), as well as the contents of the spinal canal (nerve roots and/or spinal cord).

Spondylosis progresses with age and often develops at multiple interspaces.

Chronic cervical degeneration is the most common cause of progressive spinal cord and nerve root compression

Question 7

Syringomyelia

Answer 7

• abnormal pathological cavity within spinal chord
• cavity fills with fluid forming a cyst which compresses spinal chord

disorder in which a cyst forms within your spinal cord. As this fluid-filled cyst, or syrinx, expands and lengthens over time, it compresses and damages part of your spinal cord from its center outward

Question 8

Acute transverse myelitis

Answer 8

• acute inflammation of spinal chord

- paraplegia/tetraplegia

Question 9

Anterior spinal artery occlusion

Answer 9

anterior spinal artery provides blood supply to most of the spinal chord
occlusion, spinal stroke

Question 10

Brown saquard syndrome

Answer 10

• hemisection of the spinal chord, half of the spinal chord is cut
  • Dorsal Column - ipsilateral loss of proprioception and vibration
  • Spinothalamic tract - contralateral loss of fine touch, pressure etc
  • Corticospinal tract - ipsilateral loss of motor movement

Question 11

Huntington’s disease

Answer 11

• hyperkinetic disorder
• degenerative disorder caused by triplet expansion of CAG gene in chromosome 4
• autosomal dominant inheritance

• Affects mechanism by which neostriatum controls cortical finction
Putamen - affects movements
caudate - affects cognition -> dementia
nucleus accumbes -> emotions affected

Question 12

Parkinson’s disease

Answer 12

• progressive adult onset, idiopathic
  • Death of dopaminergic neurons in the substantia niagra,
  • Substantia niagra helps to initate and calibrate movements
• Resting tremor
• Postural instability

Question 13

Lewy body dementia

Answer 13

• caused by build up of lewy body proetins in the brain