Lecture 2: Nervous System 2

Question 1

What is the CNS comprised of?

Answer 1

the brain and spinal cord

Question 2

What is the PNS defined as?

Answer 2

the nerves connecting the CNS to the body, and includes a number of ganglia at specific locations along these peripheral nerves

Question 3

What are Brodmann areas of the brain?

Answer 3

result of microscopic analysis of the whole brain, looking for differences in organisation -> based on cellular differences

Question 4

Where is the brainstem located?

Answer 4

between the diencephalon (inter-brain) and the spinal cord

Question 5

What is the brainstem composed of?

Answer 5

the midbrain, pons and medulla oblongata

Question 6

What is the central sulcus surrounded by?

Answer 6

the primary somatosensory cortex and the primary somatomotor cortex

Question 7

What is the lateral fissure surrounded by?

Answer 7

primary auditory and gustatory cortices

Question 8

What is the calcerine sulcus surrounded by?

Answer 8

primary visual cortex

Question 9

Where are the upper motor neurons located?

Answer 9

in the primary motor cortex

Question 10

Where are the lower motor neurons located?

Answer 10

in the spinal cord

Question 11

What is the motor homunculus?

Answer 11

the size of cortical surface responsible for a part of the body is proportional to the degree of motor control needed for that part

Question 12

What are primary cortices surrounded by?

Answer 12

secondary cortices and secondary cortices are surrounded by tertiary (highest order) cortices

Question 13

What is each lobe of the brain composed of?

Answer 13

functional cortical areas called the primary, secondary and tertiary cortex

Question 14

In which direction does a motor signal travel through the brain to initiate movement?

Answer 14

from the prefrontal cortex (highest order) to the supplementary motor cortex and the premotor cortex (secondary motor cortices) to the primary motor cortex to the spinal cord -> somatomotor output

Question 15

What does the SMC and PMC contribute to?

Answer 15

learning sequence of movements and stores skilled (know-how), sensory integration and bilateral coordination (especially upper limbs)

Question 16

What does lesion/damage to the primary motor cortex or upper motor neuron result in?

Answer 16

paresis or paralysis (spastic) - i.e. hypertonia

Question 17

What does lesion/damage to the lower motor neuron either in the spinal cord, ventral root or nerve result in?

Answer 17

paresis or paralysis (flaccid) i.e. hypotonia/atonia

Question 18

What does lesion/damage to the premotor cortex / supplementary motor area / other movement planning areas result in?

Answer 18

apraxia

Question 19

What is apraxia?

Answer 19

inability to execute a voluntary motor movement despite being able to demonstrate normal muscle function; it also includes ability to initiate a movement

Question 20

What are the two cortico-spinal tracts which travel from the motor cortex to the ventral horn of the spinal cord?

Answer 20

the lateral and anterior cortico-spinal tracts / motor systems

Question 21

How many upper motor neuron axons cross to the other side of the body?

Answer 21

most (80%) cross at the level of the brainstem in the lateral cortico-spinal tract and a few (20%) cross at the level of the spinal cord in the anterior cortico-spinal tract

Question 22

What is the internal capsule?

Answer 22

a collection of myelinated axons situated close to the basal ganglia and is the location of the major cortico-spinal tract

Question 23

What does the internal capsule contain?

Answer 23

contains all of the upper motor neuron axons

Question 24

What are the terms lateral and anterior derived from?

Answer 24

from where in the spinal cord the descending tracts are found

Question 25

Where do upper motor neuron axons cross?

Answer 25

at the level of the medulla in the brainstem within the medullary pyramids

Question 26

Where are axons found in the pyramidal pathways for motor control?

Answer 26

in the pyramids of the medulla -> involved in controlling voluntary movements

Question 27

Where are cell bodies of the lower motor neurons found?

Answer 27

in the ventral horn of the spinal cord

Question 28

What are the types of motor and descending pathways in the body?

Answer 28

pyramidal tracts and extrapyramidal tracts

Question 29

What are the types of sensory and ascending pathways in the body?

Answer 29

dorsal column medial lemniscus system, spinocerebellar tracts and the anterolateral system

Question 30

What is the pyramidal system?

Answer 30

pathway for voluntary movement

most fibres originate in motor cortex and cross to contralateral side at the medulla

Question 31

What is the extrapyramidal system?

Answer 31

pathways for coordination of movement and control posture / muscle tone
cortex can influence this system via inputs to brain stem