Basis of the CNS

Question 1

What are the basic components of the CNS?

Answer 1

• cerebral hemispheres
• brainstem and cerebellum
• spinal cord

Question 2

What are the basic components of the PNS?

Answer 2

• Dorsal and ventral roots
• spinal nerves
• peripheral nerves.

Question 3

What are the parts of the brainstem?

Answer 3

1. Midbrain (mesencephalon)
2. Pons
3. Medulla

Question 4

What does the midbrain do?

Answer 4

• eye movements and reflex responses to sound and vision.
• It can also make decisions whether the stimulus is dangerous or not
• –> it also listens and orientates the body appropriately.

Question 5

What does the Pons do?

Answer 5

• These are for feeding and sleep. –> pons are the important mediator of the sleep wake cycle.
• –> the trigeminal nerve is attached here and it drives the muscles of mastication, so the sucking and chewing reflects is found here.
• pons also have horizontal fibres which join the 2 parts of the cerebellum together.

Question 6

What does the medulla do?

Answer 6

• It is important in the basic survival function.
• They have cardiovascular and respiratory centres.
• They contain a major motor pathway (medullary pyramids, which ultimately decussate.
• -> decussate means they cross over each other.
• -> The medullary pyramids are two prominent bulges on the front of the medulla, which have motor neurones which help to do motor functions.

Question 7

What is the structure that is in between the two cerebral hemispheres.

Answer 7

The great longitudinal fissure.

Question 8

What does the pre-central gyrus do and where is it?

Answer 8

• It is the motor part of the brain.

- It goes anterior to the central sulcus.

Question 9

What does the post central gyrus do and where is it?

Answer 9

• It is the sensory part of the brain.

- It is the posterior part of the brain.

Question 10

How can you assume if it is sensory?

Answer 10

• if it is dorsal or posterior.

Question 11

How can you assume if it is ventral?

Answer 11

• if it is ventral.

Question 12

What is a sulcus?

Answer 12

A groove or furrow in the brain separating adjacent gyri.

Question 13

What is a gyrus?

Answer 13

A ridge or fold in the brain –> surface raised areas.

Question 14

What is a fissure?

Answer 14

A large crack or split between adjacent large areas of the brain.

Question 15

What does the frontal lobe do?

Answer 15

It is for:

• higher cognition
• motor function
• speech

Question 16

What does the parietal lobe do?

Answer 16

It is for:

• sensation
• spatial awareness

Question 17

What does the temporal lobe do?

Answer 17

• memory
• smell
• hearing

Question 18

What does the occipital lobe do?

Answer 18

• vision

Question 19

What does the cerebellum do?

Answer 19

• co-ordination
• motor learning
• also used in cognition

Question 20

What is the optic chiasm?

Answer 20

It is a site where fibres in the visual system cross over.

Question 21

What is the uncus?

Answer 21

It is part of the temporal lobe that can herniate, compressing the midbrain.

• –> It is the most medial portion.
• –> It can squash the adjacent midbrain resulting in paralysis and compression of the 3rd nerve.

Question 22

What are the medullary pyramids?

Answer 22

This is the location of descending motor fibres.

Question 23

What is the corpus callosum?

Answer 23

• It is on the top

- It has fibres that connects the two cerebral hemispheres.

Question 24

What is the Thalamus?

Answer 24

This is a sensory relay station that projects to the sensory cortex.

Question 25

What is the hypothalamus?

Answer 25

It is an essential centre for homeostasis.