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Question 1

What do the descending tracts do?

Answer 1

Carry the efferent fibres from the brain down to the motor efferents to bring about action in response to sensory afferent input.

Question 2

How can the descending motor pathways be divided?

Answer 2

PyramidalExtra-pyramidal

Question 3

Give the pathways that are classified as pyramidal pathways

Answer 3

Corticospinal tractCorticobulbar tract

Question 4

Give some characteristics of the pyramidal pathways

Answer 4

Have direct contact with the lower motoneuronesTravel through the medullary pyramidsControl voluntary movements

Question 5

Describe the corticospinal tract

Answer 5

Cell bodies - in cerebral cortexDivided into anterior and lateral componentsAnterior = 10% of fibres, stay on ipsilateral side, decussate at a cerain vertebral level and synapse with LMNs. Lateral = 90% of fibres, decussate at medulla and continue down the contralateral side. Terminate in the ventral horn, where they synapse with inhibitory interneurones and LMNs.

Question 6

Describe the path of the corticospinal tract

Answer 6

Fibres arise from the cerebral cortex. The axons converge and pass through the internal capsule down to the midbrain, pons and medulla. Then, they travel down in the spinal cord to their synapses with lower motoneurones

Question 7

Describe the corticobulbar tract

Answer 7

Originates in the cerebral cortex. Control muscles of facial expression & extraocular muscles. Terminate in the cranial nerve motor nuclei in the midbrain, pons and medulla

Question 8

Describe the path of the corticobulbar tract

Answer 8

Descends through the internal capsule to the brainstem and decussates at the brainstem. Next, they terminate in the midbrain, pons and medulla.

Question 9

What does the corticobulbar tract innervate?

Answer 9

Voluntary movements of the head and neck. Contralateral cranial nerve nucleus.

Question 10

What are the extrapyramidal tracts?

Answer 10

VestibulospinalTectospinalReticulospinalRubrospinalOlivospinal

Question 11

Describe the extrapyramidal pathways

Answer 11

Are the brainstem pathwaysHave indirect contact (polysynaptic) with the motoneurones, via the regulation of ventral horn interneurones

Question 12

Describe the vestibulospinal tract

Answer 12

Responsible for balance and posture of the rest of the bodyArises from the vestibular nucleusFibres do not decussate

Question 13

Describe the reticulospinal tract

Answer 13

Fibres arise from the emdullaDescend bilaterally to all levels of the spinal cordHave some decussation in the brainstem. Facilitate extensor spinal reflexes.

Question 14

Describe the rubrospinal tract

Answer 14

Arises from neurones of the red nucleusDecussate in the midbrainDescend contralaterally in the spinal cordFacilitates flexor motoneurones and inhibits extensor motoneurones

Question 15

Describe the tectospinal tract

Answer 15

Involved in directing head movements in response to visual and auditory stimuli. Neurones arise from the tectum of the brainstemDecussate within the brainstemTerminate in the upper cervical segments

Question 16

Describe Amyotrophic lateral sclerosis/ Lou Geh rig’s disease

Answer 16

Is a progressive degenerative disease where the corticospinal tracts and ventral horns degenerate. Has an unknown cause

Question 17

Give the progression and symptoms that can arise from ALS/Lou Gehrig’s.

Answer 17

Weakness and loss of control t muscles in the hands, trunk and lower limbs, often with the lower limbs affected first. Bladder and bowel function can be impaired due to loss of descending automatic pathways.

Question 18

Describe Borwn-Sequard syndrome

Answer 18

Loss of sensation a motor function due to lateral hemisection of the spinal cord

Question 19

What are some causes of brown-sequard syndrome?

Answer 19

TumourTraumaIschaemiaInfectionInflammatory conditions

Question 20

What will a patient with brown-sequard synrome present with?

Answer 20

Spastic paralysis of ipsilateral sideLoss of fine touch and proprioception on ipsilateral sideLoss of pain, temp and pressure sensation of the contralateral side

Question 21

What is the treatment of brown-sequard syndrome?

Answer 21

Treat the underlying cause- classic cause is stab wound to the back

Question 22

Describe anterior spinal artery syndrome

Answer 22

Ischaemia to the anterior spinal artery which affects the corticospinal tracts

Question 23

What does spinal artery syndrome cause?

Answer 23

Motor paralysis as well as impaired pain and temperature syndrome

Question 24

Describe syringomyelia

Answer 24

Describes the developemnt of a cyst/cavity around the central canal which grows and spreads over time

Question 25

What effects does syringomyelia have?

Answer 25

Disrupts the spinothalamic tract (decussates just ventral to the central canal)Causes reduced temperature and pain sensation at the level of the lesion, as well as affecting fine touch, proprioception and vibration plus the motor system as it descends.