CNS Organisation

Question 1

What does the CNS include?

Answer 1

the brain and spinal cord

Question 2

How many pairs of spinal nerves and cranial nerves are there respectively?

Answer 2

• 31 spinal
• 12 cranial

Question 3

Where is the brain located?

Answer 3

in the cranial cavity protected by the skull and meninges

Question 4

What is the meninges?

Answer 4

the tough connective tissue that covers and surrounds the brain

Question 5

What is the brain divided into?

Answer 5

• forebrain
• midbrain
• hindbrain

Question 6

What does the forebrain include?

Answer 6

the cerebrum and the diencephalon

Question 7

What does the hindbrain include?

Answer 7

the medulla oblongata, pons and cerebellum

Question 8

What does the brainstem include?

Answer 8

the midbrain, pons and medulla oblongata

Question 9

What makes up the vertebral column?

Answer 9

gaps between vertebrae of the spine

Question 10

How is the CNS different to the PNS?

Answer 10

• the CNS has little to no capacity to regenerate after injury
• the CNS contains myelin that is inhibitory to neuro-regeneration

Question 11

Where does the spinal cord end?

Answer 11

the tailbone (coccyx)

Question 12

What is the retina?

Answer 12

essentially an outgrowth of the brain that is part of the CNS

Question 13

What nerve is the optic nerve?

Answer 13

cranial nerve 2

Question 14

What are the 31 spinal nerves?

Answer 14

• 8 cervical
• 12 thoracic
• 5 lumbar
• 5 sacral
• 1 coccygeal

Question 15

What is the largest part of the brain?

Answer 15

the cerebrum

Question 16

What does the cerebrum consist of?

Answer 16

2 cerebral hemispheres separated by the longitudinal fissure

Question 17

What is on the surface of the cerebral hemispheres?

Answer 17

a thin 5mm layer of grey matter

Question 18

What is grey matter?

Answer 18

a collection of neuronal cell bodies called the cerebral cortex

Question 19

What are gyri?

Answer 19

the folds and bumps in the brain

Question 20

What are sulci?

Answer 20

the grooves of the brain

Question 21

What does the central sulcus form?

Answer 21

the boundary between the frontal and parietal lobes on the lateral and medial surfaces of the cerebral hemispheres

Question 22

Where is the occipital lobe?

Answer 22

the very back of the brain

Question 23

What is somatosensation?

Answer 23

sensation from the body surface e.g. pain, temperature, pressure, proprioception

Question 24

What is proprioception?

Answer 24

position sense i.e. knowing where your body parts are without looking

Question 25

What is required for sensation to reach consciousness?

Answer 25

the primary somatosensory cortex

Question 26

What are the ascending and descending tracts respectively?

Answer 26

- ascending = sensory signals - descending = motor signals

Question 27

What is responsible for initiating all voluntary movement?

Answer 27

the primary motor cortex in the frontal lobe

Question 28

What are the 4 lobes of the brain and where are they?

Answer 28

- frontal lobe - anterior to central sulcus and superior to lateral fissure - parietal lobe - posterior to central sulcus and superior to lateral fissure - temporal lobe - inferior to lateral fissure - occipital lobe - posterior to parietal and temporal lobes

Question 29

Where is the hippocampus?

Answer 29

rolled in part of the cerebral cortex

Question 30

What is the hippocampus essential for?

Answer 30

the formation of new memories

Question 31

What is the most vulnerable part of the brain?

Answer 31

the hippocampus, especially during global ischaemia and early stages of Alzheimer's

Question 32

What does the hippocampus contain?

Answer 32

neurons and glial cells

Question 33

What does a neuron consist of?

Answer 33

a cell body, axon and dendrite

Question 34

What is the most common excitatory and inhibitory neurotransmitter respectively?

Answer 34

- excitatory = glutamate - inhibitory = GABA

Question 35

What do glutamate and GABA receptors do respectively?

Answer 35

- glutamate opens sodium channels and excites the postsynaptic neuron - GABA opens chloride channels and inhibits the postsynaptic neuron

Question 36

Where do glutamate and GABA synapse respectively?

Answer 36

- glutamate = spines of neurons - GABA = shafts of dendrites

Question 37

What are the most common neurotransmitters in the PNS?

Answer 37

ACh and noradrenaline

Question 38

Where are dopamine and ACh important respectively?

Answer 38

- dopamine = Parkinson's disease - ACh = Alzheimer's disease

Question 39

Where does the longest axon travel?

Answer 39

from the toe to the brain

Question 40

What do APs cause?

Answer 40

the release of a neurotransmitter from the axon terminal which then diffuses rapidly across the synaptic cleft and binds to the receptors on the dendrite of the next neuron

Question 41

What do glial cells do?

Answer 41

support the function of neurons

Question 42

Give examples of glial cells

Answer 42

- astrocytes - oligodendrites - microglia (macrophages)

Question 43

Give examples of neuronal membrane proteins

Answer 43

- Na+/K+ ATPase - glucose transporter

Question 44

Give examples of glial membrane proteins

Answer 44

glutamate transporter

Question 45

Where is white matter found?

Answer 45

in the deeper tissues of the brain containing axons covered in lipid material myelin

Question 46

What is the largest white structure of the brain?

Answer 46

the corpus callosum

Question 47

What is the internal capsule?

Answer 47

a white matter structure where a large number of motor and sensory fibres travel to and from the cortex

Question 48

What are nuclei?

Answer 48

collections of neuronal cell bodies in the CNS

Question 49

Where is the diencephalon and what does it consist of?

Answer 49

between the two hemispheres and consists of the dorsal thalamus and the hypothalamus which are separated by the hypothalamic sulcus

Question 50

What is the last relay station before the signal is sent to the cerebral cortex?

Answer 50

the thalamus

Question 51

What is the diencephalon important for?

Answer 51

the regulation of movement and relay of sensory information

Question 52

What is homeostasis?

Answer 52

the maintenance of the internal balance of the body e.g. osmolarity/temperature/hormone levels of the blood

Question 53

What does the hypothalamus do?

Answer 53

- influence the pituitary gland - control the secretion of hormones - alter homeostasis by direct neuronal projection

Question 54

What does the ANS control?

Answer 54

the internal organs of the body

Question 55

What is the thalamus?

Answer 55

a large mass of grey matter (nuclei) on either side of the third ventricle

Question 56

What is the third ventricle?

Answer 56

a narrow funnel-shaped structure in the centre of the brain

Question 57

What does the hypothalamus form?

Answer 57

the lower part of the lateral wall and floor of the third ventricle

Question 58

What does the midbrain connect?

Answer 58

the forebrain to the hindbrain

Question 59

What are the muscles of the eye controlled by the cranial nerves?

Answer 59

the ciliary body and iris

Question 60

Which brain structures have ascending and descending tracts?

Answer 60

- midbrain - forebrain - pons - medulla oblongata

Question 61

What are the cranial nerves of the midbrain?

Answer 61

III and IV

Question 62

What are the nuclei of the midbrain associated with?

Answer 62

cranial nerves III, IV and V and visual and auditory pathways

Question 63

Where is the pons?

Answer 63

inferior to the midbrain and superior to the medulla oblongata

Question 64

What are the cranial nerves of the pons?

Answer 64

V, VI, VII and VIII

Question 65

What is the most inferior portion of the brain?

Answer 65

medulla oblongata

Question 66

What are the cranial nerves of the medulla oblongata?

Answer 66

IX, X, XI and XII

Question 67

What are the nuclei of the medulla oblongata associated with?

Answer 67

cranial nerves V, IX, X, XI, XII and cardiovascular and respiratory function

Question 68

Where is the cerebellum located?

Answer 68

posterior to the pons and the medulla oblongata

Question 69

What is the cerebellum involved in?

Answer 69

the regulation of balance and coordinated movement

Question 70

What does the cerebellum consist of?

Answer 70

a midline portion (vermis) and 2 hemispheres connected to the brainstem

Question 71

Where is the spinal cord continuous with the brain?

Answer 71

at the foramen magnum of the skull which tapers off into the conus medullaris

Question 72

Why is there difference in length between the spinal cord and the vertebral column?

Answer 72

due to the differential growth of the spinal cord

Question 73

What does a cross section of the spinal cord contain?

Answer 73

- spinal nerves - grey matter - fibre tracts