NEURO 129 Spinal Cord Compression

Question 1

Through what structure does the sensory input enter the spinal cord?

Answer 1

Dorsal root

Question 2

Through what structure does the efferent response leave the spinal cord?

Answer 2

Ventral root

Question 3

What are three musculoskeletal sensory receptors?

Answer 3

Muscle spindles, Golgi tendon organ and joint receptors

Question 4

What does the muscle spindle detect?

Answer 4

Stretch in the muscle

Question 5

How is the muscle spindle kept under tension and why?

Answer 5

by gamma motor fibres which keep it tense as without tension it would be unable to detect any changes in stretch

Question 6

What is the purpose of the golgi tendon organ?

Answer 6

To provide inhibitory feedback “inverse myotatic reflex”

Question 7

What activates the golgi tendon organ and what is the response?

Answer 7

Prolonged contraction or stretch producing muscle inhibition - prevents tendon damage

Question 8

Describe the basic spinal reflex - the knee jerk reaction

Answer 8

Tapping patellar ligament, stretches quadriceps muscle, activates 1a afferent nerve –> synapses with alpha motor neurone = subsequent muscle contraction
This has an excitatory synapse with an inhibitory interneurone which inhibits the alpha motor neurone causing muscle relaxation

Question 9

What are Renshaw cells?

Answer 9

Inhibitory interneurones

Question 10

What do Renshaw cells do?

Answer 10

Release glycine back onto the alpha motor neurone to inhibit it

Question 11

Where do instructions for voluntary movement lie in the brain?

Answer 11

In the motor cortex - the motor homonculus

Question 12

What is most of the motor homonculus devoted to?

Answer 12

Hands, face and tongue

Question 13

What is the main descending motor pathway in the CNS?

Answer 13

The corticospinal tract

Question 14

Where does the corticospinal tract originate?

Answer 14

Pyramidal cells of the motor cortex

Question 15

Where does the corticospinal tract cross over?

Answer 15

The pyramids of the medulla

Question 16

What are the 4 other areas, besides the motor cortex, that the corticospinal tract arises from?

Answer 16

Primary somatosensory receiving area, premotor cortex, supplementary area and posterior parietal cortex

Question 17

What is apraxia?

Answer 17

An inability to produce a specific motor act even though sensory and motor pathways remain intact

Question 18

What are the two main ascending tracts to the CNS?

Answer 18

Spinothalamic and the Dorsal Columns

Question 19

What does the spinothalamic tract carry sensory information about?

Answer 19

Pain, tempterature, touch and pressure

Question 20

What does the dorsal column carry sensory information about?

Answer 20

Joint position and fine discriminatory touch

Question 21

Where does the spinothalamic tract deccusate?

Answer 21

At the level it enters the spinal cord

Question 22

Where do the dorsal columns decussate?

Answer 22

In the medulla

Question 23

What are the main signs of an UMN lesion?

Answer 23

Paralysis/weakness of movement of affected muscles
HyPERreflexia
HyPERtonia

Question 24

Why is there Hypertonia/reflexia in an UMN lesion?

Answer 24

Due to lack of inhibition

Question 25

What are the main signs of a LMN lesion?

Answer 25

HyPOreflexia
Fasiculations
HyPOtonia
Muscle atrophy and denervation

Question 26

What is Cauda Equina Syndrome due to?

Answer 26

Compression of the lumbar and sacral nerve roots within the cauda equina

Question 27

What is motor neurone disease due to?

Answer 27

Disease of the anterior horn cells of the spinal cord

Question 28

What is Myasthesia gravis?

Answer 28

Acquired autoimmune disease against the acetylcholine receptor at the NMJ

Question 29

What is the main the clinical feature of myasthesia gravis?

Answer 29

Muscle weakness and fatiguability

Question 30

What is a muscular dystrophy and give an example

Answer 30

Inherited disorder of muscle e.g. Duchennes

Question 31

What happens in muscular dystrophy?

Answer 31

There is progressive muscle wasting and weakness with proximal muscles being affected worse than distal ones

Question 32

What is a radiculopathy?

Answer 32

A Nerve root compression

Question 33

What is Brown-Sequard syndrome?

Answer 33

A lesion in one half of the spinal cord - hemisection

from trauma or disc hernia or compressive tumour

Question 34

What is a syringomelia

Answer 34

Expanded central canal in cervical region

Question 35

In UMN lesion what is pyramidal weakness?

Answer 35

Where the flexors of the lower limb and extensors of the upper limb are stronger than the opposite