S4 Basics of the central nervous system

Question 1

Describe the CNS

Answer 1

Cerebral hemispheres
Brainstem and Cerebellum
Spinal cord
cannot regenerate axons, apart from few regions
myelination achieved by oligodendrocytes
tumours can be benign and malignant
has immune system - microglia

Question 2

describe PNS

Answer 2

dorsal and ventral roots
spinal nerves 
peripheral nerves
can regenerate axons - wallerian degeneration
myelination by schwann cells
tumours - benign
peripheral immune response

Question 3

which hemispheres are dorsal and ventral in the brain

Answer 3

because brain flexes around the level of the midbrain, the superior part of the hemisphere is dorsal and inferior brain is ventral
in imaging, right and left are reversed

Question 4

what are the components of the brainstem ?

Answer 4

midbrain (mesenchephalon) - eye movements and reflex responses to sound and vision
pons - feeding and sleep
medulla - cardiovascular and respiratory centres and contains major motor pathway (medullary pyramids)

Question 5

what does decussation mean

Answer 5

left side brain controls right body. fibres cross from one hemisphere to the other side of the CNS

Question 6

what is a sulcus ?

Answer 6

a groove or furrow in the brain seperating adjacent gyri

Question 7

what is a gyrus ?

Answer 7

a ridge or fold in the brain

Question 8

what is a fissure ?

Answer 8

a large crack or split between adjacent large areas of the brain

Question 9

what are different lobes of the brain and its functions

Answer 9

frontal lobe : higher cognition, motor function and speech
parietal lobe : sensation, spatial awareness
temporal lobe : memory, smell, hearing
occipital lobe : co-ordination and motor learning

Question 10

what is the optic chiasm ?

Answer 10

a site where fibres in the visual system cross over, lies close to the pineal gland so this can compress the OC

Question 11

what is the uncus ?

Answer 11

part of the temporal lobe that can herniate, compressing the midbrain

Question 12

what are the medullary pyramids ?

Answer 12

location of descending motor fibres

Question 13

what is the corpus callosum ?

Answer 13

fibres connecting the two cerebral hemispheres

Question 14

what is the thalamus ?

Answer 14

sensory relay station projecting to sensory cortex

Question 15

what is the hypothalamus ?

Answer 15

essential centre for homeostasis

Question 16

how can atherosclerotic disease within ICA cause transient loss of vision ?

Answer 16

ICA goes through the carotid canal through the cavernous sinus then gives off the ophthalmic artery, which goes through the optic canal which gives rise to the central retinal artery, which gives blood to the eyes. lack of 02 to this artery causes loss of vision

Question 17

at what part of the CNS do the motor fibres arising from the primary motor cortex cross to the opposite side

Answer 17

medullary pyramid in the brainstem