Neuro Practical 2.1.3

Question 1

what hemisphere is brocas area usually located in?

Answer 1

the dominant - usually left

Question 2

Which region of the primary motor cortex gives rise to the upper motor neurons concerned with cortico-bulbar projections?

Answer 2

betz layer 5

Question 3

Which region of the primary motor cortex gives rise to the upper motor neurons concerned with cortico-spinal projections?

Answer 3

betz layer 5

Question 4

Where in the internal capsule are the corticospinal and corticobulbar fibres located?

Answer 4

posterior limb
The corticospinal fibres are nearer the retrolenticular region, corticobulbar fibres are nearer the genu.
 

Question 5

what is the central sulcus?

Answer 5

divides the primary motor and primary sensory cortex

Question 6

where is the premotor cortex?

Answer 6

anterior to the primary motor cortex

Question 7

what is the cortico-spinal nerves function?

Answer 7

voluntary control of the limbs and trunk

Question 8

what is the function of the cortico-bulbar nerves

Answer 8

voluntary movements of the head and neck, speech, swallowing, facial expresions

Question 9

Where are the cell bodies of upper motor neurons in the corticospinal tract primarily located?

Answer 9

Principally in the primary motor cortex

Question 10

Where are the cell bodies of lower motor neurons located?

Answer 10

In the ventral grey horn of the spinal cord. Their axons exit the spinal cord in the ventral root, and merge with the dorsal root to form a mixed spinal nerve.

Question 11

What happens to the majority of descending corticospinal motor axons at the decussation of the pyramids?

Answer 11

they decussate to the contralateral side

Question 12

Apart from their location, what is the main difference between the lateral and ventral corticospinal tracts?

Answer 12

Fibres in the lateral tract decussated in the medulla; fibres in the ventral tract are ipsilateral and will decussate in the spinal cord close to the vertebral level where their target lower motor neurons are located

Question 13

describe the corticospinal tract

Answer 13

Primary motor cortex -> Corona radiata -> Internal capsule -> Crus cerebri -> Pyramid -> Decussation of the pyramid -> Lateral corticospinal tract -> Ventral horn

Question 14

Do upper motor neurons in the lateral and ventral corticospinal tracts synapse on lower motor neurons in the ipsilateral or contralateral ventral grey horn of the spinal cord?

Answer 14

Nearly all synapse on to lower motor neurons on the contralateral side

Question 15

what is another name for the corticospinal tract?

Answer 15

the pyramidal tract

Question 16

what is the function of the corticospinal tract?

Answer 16

voluntary control of movement

Question 17

what controls involuntary movement?

Answer 17

the extrapyramidal tracts

Question 18

what are the extrapyramidal tracts?

Answer 18

• Rubrospinal – UMN cell bodies in the red nucleus
• Vestibulospinal – UMN cell bodies in the vestibular nuclei
• Tectospinal – UMN cell bodies in the superior colliculus
• Reticulospinal – UMN cell bodies in the reticular formation (hard to identify!)

Question 19

where does the vestibulospinal nuceleus recieve information from and what does it activate?

Answer 19

receives from the labryinthine system and cerebellum
activates the extensor motor neurones concerned with maintenance of anti-gravity posture

Question 20

where does the rubrospinal nucleus recieve information from and activate?

Answer 20

receives: cortex and cerebellum
activates: motor neurones and flexor muscles

Question 21

where does the reticulospinal nucleus receive information from and what deos it activate?

Answer 21

receives: hypothalamus
actrivates : motor neurones concerned with reflex activity, muscle tone, breathing and circulatory system

Question 22

where does the tectospinal nucleus recieve information from and activate

Answer 22

receives: visual system
activates: motor neurones reflex response to visual stimulo

Question 23

what is the basal ganglia?

Answer 23

a group of subcortical nuclei with extensive connections to the cortex and thalamus (particlularly VA nucleus) they act as a checking system for motor activity - facilitate wanted movements and inhibit unwanted ones

Question 24

what are the major componenets of the basal ganglia?

Answer 24

caudate nucleus, putamen, globus pallidus, substantia nigra

Question 25

what are the 2 principle functional pathways of the basal ganglia?

Answer 25

direct pathway - promotes movement
indirect pathway - inhibits movement

Question 26

what is the role of the substantia nigra

Answer 26

it uses dopamine as a neurotransmitter in the direct pathway it activates the striatum, in the inderict pathway it inhibits it