Basic neurology & disease

Question 1

What does an afferent neurone do?

Answer 1

Carries information from sensory receptors into the CNS.

Question 2

Where do afferent neurones enter the CNS?

Answer 2

Through dorsal root ganglia.

Question 3

What does an efferent neurone do?

Answer 3

Carries motor signals from the CNS to effector muscles.

Question 4

Where do efferent neurones leave the CNS?

Answer 4

Thought ventral root ganglia.

Question 5

What is a ganglion?

Answer 5

A collection of neurones or cell bodies of neurones outside the CNS.

Question 6

What do muscle spindles detect?

Answer 6

Muscle stretch.

Question 7

What neurones do muscle spindles cause APs in?

Answer 7

1a afferent neurones.

Question 8

What do 1a afferent neurones innervate?

Answer 8

Alpha motor neurones & inhibitory interneurones.

Question 9

What do golgi tendons detect?

Answer 9

Muscle tension.

Question 10

What neurones doe golgi tendons cause APs in?

Answer 10

1b afferent neurones.

Question 11

What does two actions result from activation of the muscle spindle?

Answer 11

Excitation of alpha motor neurone projecting to the homonymous muscle > contraction of the homonymous muscle.

Excitation of the inhibitory interneurone > inhibition of the alpha motor neurone projecting to the heteronymous muscle > relaxation of the heteronymous muscle.

Question 12

What are renshaw cells & what is their role?

Answer 12

Inhibitory neurones which release glycine onto alpha motor neurones to make the spinal reflex transient.

Question 13

What does tetanus inhibit?

Answer 13

Glycine release.

Question 14

Explain the myotactic reflex?

Answer 14

Stretch of a muscle > stretch of the muscle spindle > AP in 1a afferent neurone > activation of the alpha motor neurone projecting to the homonymous muscle > contraction of the homonymous muscle.

The 1a afferent neurone also activates the inhibitory interneurone projecting to the alpha motor neurone of the heteronymous muslce > relaxation of the heteronymous muscle.

Question 15

Explain the inverse myotactic reflex?

Answer 15

Increased muscle tension > activation of the GTO > AP in 1b afferent neurone > excitation of inhibitory interneurone > inhibition of the alpha motor neurone projecting to the homonymous muscle > relaxation of the homonymous muscle.

Question 16

What are synergistic muscles?

Answer 16

Muscles that contract together to produce the same movement.

Question 17

What is the role of gamma motor neurones?

Answer 17

Ensure the muscle spindle is always kept under tension.

Question 18

What are the most important tracts for voluntary movement?

Answer 18

Corticospinal tracts.

Question 19

Where do corticospinal tracts originate?

Answer 19

Pyramidal cells of the motor cortex.

Question 20

Where do corticospinal tracts decussate?

Answer 20

At the decussation of the pyramids in the medulla.

Question 21

Where is the premotor area found & what is its role?

Answer 21

Found in the frontal lobe.

Required for the planning of movements & movements that require visual guidance.

Question 22

Where is the primary somatosensory cortex found & what is its role?

Answer 22

Found in the parietal lobe.

Required for filtering out of irrelevant sensory information.

Question 23

Where is the supplementary motor area found & what is its role?

Answer 23

Found in the frontal lobe.

Required for coordinating voluntary movements.

Question 24

What is anosognosia?

Answer 24

Unawareness of a disability.

Question 25

Damage to which area may result in anosognosia?

Answer 25

The posterior parietal cortex.

Question 26

What is apraxia?

Answer 26

Inability to produce a specific motor act even though sensory & motor pathways are intact.

Question 27

Damage to which areas result in apraxia?

Answer 27

Primary motor cortex. Supplementary motor area. Posterior parietal cortex.

Question 28

What are the two types of apraxia?

Answer 28

Ideomotor apraxia: > Cannot execute a specific movement on request even though the movement is known. Ideational apraxia: > Cannot conceptualise the movement.

Question 29

What information does the lateral spinothalamic tract carry?

Answer 29

Pain & temperature.

Question 30

What information does the dorsal column carry?

Answer 30

Proprioception & soft touch.

Question 31

What are the classic signs of a UMN lesion?

Answer 31

Hyper-reflexia. Spasticity. Postivie babinski reflex.

Question 32

What are the classic signs of a LMN lesion?

Answer 32

Hypo-reflexia / areflexia. Fasiculations. Muscle atrophy.

Question 33

Where does the lateral spinothalamic tract decussate?

Answer 33

At the level is enters the spinal cord.

Question 34

What level does the dorsal column decussate?

Answer 34

At the level of the medulla.

Question 35

What is Brown-Sequard syndrome?

Answer 35

Lateral hemisection of the spinal cord.

Question 36

What are the signs of Brown-Sequard syndrome?

Answer 36

Loss of motor function on the ipsilateral side at the level of & below the lesion. Loss of proprioception & soft touch on the ipsilateral side at the level of & below the lesion. Loss of pain & temperature sensation on the contralateral side at the level of & below the lesion.

Question 37

What are the causes of spinal cord disease?

Answer 37

``` Trauma. Infection. Demyelination (i.e. MS). Compression. B12 deficiency. Anterior spinal artery infarction. Inflammatory (i.e. SLE). ```

Question 38

What does paresis mean?

Answer 38

Weakness.

Question 39

What does plegia mean?

Answer 39

Paralysis.

Question 40

What does myelo mean?

Answer 40

Pathology of the spinal cord.

Question 41

What does radiculo mean?

Answer 41

Pathology of the nerve root.

Question 42

What does neuro mean?

Answer 42

Pathology of the peripheral nerves.

Question 43

What does myo mean?

Answer 43

Pathology of muscle.

Question 44

What are the functions of UMN pathways?

Answer 44

Dampening of the reflex arc. Suppressing muscle over-activity & spasm. Suppressing primitive reflexes (i.e. babinkski).

Question 45

What is a LMN?

Answer 45

anterior grey horn cell.

Question 46

What is a UMN?

Answer 46

Anything above the synapse of the anterior grey horn cell.

Question 47

What are the classic signs of muscle disease?

Answer 47

Proximal muscle weakness & pain. Muscle wasting or hypertrophy. Normal reflexes. Raised CK.

Question 48

What is papilloedema & what does it suggest?

Answer 48

Swelling of the optic nerve - suggests raised ICP.

Question 49

What is dysarthia?

Answer 49

Difficulty with speech articulation.

Question 50

What pathways degenerate in motor neurone disease?

Answer 50

UMN: > corticospinal tracts. > corticobulbar tracts. LMN: > loss of anterior horn cell.

Question 51

What are the signs of motor neurone disease?

Answer 51

Hyper-reflexia. Pseudobulbar palsy. Fasiculations. Elevated CK.

Question 52

What drugs can cause muscle disease?

Answer 52

Statins. Steroids. Anti-virals. Chloroquine.

Question 53

What are the signs of polymyositis?

Answer 53

Proximal muscle weakness.

Question 54

What are the signs of dermatomyositis?

Answer 54

Promxial muscle weakness. Rash over hands & face. Mainly in adults with malignancy.

Question 55

What are the signs of inclusion body myositis?

Answer 55

Proximal leg muscle & long finger flexor weakness. | Mainly in the elderly.

Question 56

What is cauda equina syndrome?

Answer 56

Compression of the cauda equina.

Question 57

What are the symptoms of cauda equina syndrome?

Answer 57

``` Bilateral sciatica. Saddle & genitalia anaesthesia. Sphincter & sexual dysfunction. Loss of ankle reflexes. Leg weakness & pain on raising. ```