27 DISEASES OF MOTOR UNITS

Question 1

Define monoplegia

Answer 1

Paralysis of a single limb

Question 2

Define hemiplegia

Answer 2

Paralysis on one side of the body

Question 3

Define paraplegia

Answer 3

Waist down paralysis

Question 4

Define quadraplegia

Answer 4

All four limbs paralysis

Question 5

Define paresis

Answer 5

Weakness

Question 6

What are the three abnormalities of muscle tone

Answer 6

Hypertonia (UMN), hypotonia (LMN), rigidity (basal ganglia)

Question 7

Describe ataxia

Answer 7

Lack of voluntary control/ coordination of muscles

Question 8

Define dysmetria

Answer 8

Lack of coordination of movement, undershoot/ overshoot. A form of ataxia

Question 9

What are four categories of involuntary muscle movement

Answer 9

Spasm (cramp), epileptic fit, tremor, dyskinesia

Question 10

Define dyskinesia

Answer 10

Involuntary muscle movements

Question 11

What are the words used to describe the type of lesion and timing of lesion

Answer 11

Focal/ diffuse

Acute/ chronic

Question 12

Where are cell bodies for motoneurons found

Answer 12

In lamina 8 and 9 of the spinal cord (spinal nerves), brainstem (cranial nerves)

Question 13

What are the two types of motoneurons

Answer 13

Alpha- extrafusal muscle fibre, generation of force

Gamma- intrafusal muscle fibres, determine sensitivity of muscle spindles

Question 14

What is the motor unit made up of

Answer 14

The alpha motoneuron and the muscle fibres it innervates

Question 15

Name the descending tracts that converge on alpha motoneurons

Answer 15

Corticospinal tract
Corticobulbar tract
Vestibulospinal tract
Reticulospinal tract
Tecto spinal tract

Question 16

Two non motor tract things that synapse with alpha motoneurons

Answer 16

1a afferent fibres from muscle spindles.

Interneurons (excitatory/inhibitory)

Question 17

What is disorder of the muscle fibre called

Answer 17

Myopathy

Question 18

What is disorder to the motoneuron called

Answer 18

Neuropathy

Question 19

List location of lesions

Answer 19

Muscle fibres
Neuromuscular junction
Lesion that affects transmission in the axon
Axotomy
Cell body of neuron

Question 20

Define muscular dystrophy

Answer 20

A group of inherited disorders characterised by deficits in muscle proteins leading to wasting/ weakness. Includes Duchennes muscular dystrophy, myotonic muscular dystrophy

Question 21

Describe the most common MD in children

Answer 21

Duchennes MD, X linked so only in boys mild symptoms in girls. Abnormal gene for protein dystrophin used in cell membranes

Question 22

Describe the most common MD in adults

Answer 22

Myotonic muscular dystrophy. Onset 3rd decade. Wasting, weakness of muscles. Myotonia (delayed relaxtion) CTG repeats in chromosome 19 coding for myotonin protien. Inherited dominant.

Question 23

Describe myasthenia gravis

Answer 23

Autoimmune condition. Immune system attacks proteins involved in Ach receptors, less synaptic transmission.

Question 24

Describe the mechanism of action of botulism toxin

Answer 24

Reduces Ach release through proteolysis of membrane proteins involved in the release of Ach. Has non muscle effects due to action on Ach release in autonomic nervous system- dry mouth, postural hypotension

Question 25

Describe Wallerian degeneration

Answer 25

Loss of synaptic transmission, axons degenerate after the lesion within days due to loss of axon survival factor, degeneration in distal parts of the neuron cell body ok. Axon regeneration occurs facilitated by schwann cells

Question 26

Name two peripheral neuropathies

Answer 26

Diabetic neuropathy (hyperglycemia causes damage to the small capillaries supplying nerves). Guillian Barre syndrome- autoimmune causing immune attack of myelin.

Question 27

Name symptoms of lower motoneuron diseases

Answer 27

Atrophy muscles
Weakness/ paralysis
Depressed or abolished reflexes
Fascinations (coarse twitches, sign of muscle denervation due to activation of individual motorunits)
Fibrillations (discharge of single muscle fibres)
No spasticity/ babinskis reflex