Central nervous system (7)

Question 1

How can we divide the brain?

Answer 1

>forebrain:
-cerebral hemispheres
- diencephalon-- thalamus and hypothalamus
>midbrain
>hindbrain:
-pons
-medulla
-cerebellum

Question 2

What is the basic function of the frontal lobe?

Answer 2

regulating and initiating motor function, language, cognitive functions (executive function/planning, attention, memory)

Question 3

What is the basic function of the parietal lobe?

Answer 3

sensation (touch, pain), sensory aspects of language, spatial orientation and self-perception

Question 4

What is the basic function of the temporal lobe?

Answer 4

processing auditory information

Question 5

What is the basic function of the occipital lobe?

Answer 5

processing visual information

Question 6

What divides the frontal and parietal lobes?

Answer 6

central sulcus

Question 7

What is the limbic lobe?

Answer 7

• includes amygdala, hippocampus, mammillary body and cingulate gyrus
• concerned w/ learning, memory, emotion, motivation and reward

Question 8

What is the insular cortex/lobe?

Answer 8

• lies deep to lateral fissure
• concerned w/ visceral sensations, autonomic control, interoception, auditory processing and visual-vestibular integration

Question 9

What are the 3 layers of the meninges?

Answer 9

• dura mater
• arachnoid mater
• pia mater

Question 10

What forms sinuses in the meninges?

Answer 10

the 2 layers of the dura

Question 11

Where is cerebrospinal fluid produced?

Answer 11

in modified epithelial cells (choroid plexus) in lateral, 3rd and 4th ventricles–> goes to sub-arachnoid space

Question 12

Where is CSF reabsorbed into the bloodstream?

Answer 12

via arachnoid villi (granulations) into superior sagittal sinus

Question 13

What are the differences between CSF and plasm?

Answer 13

• lower pH
• less glucose
• much less protein
• less K+

Question 14

Where do the efferent/afferent signals travel to/from in the spinal cord (N.B. roots)?

Answer 14

afferent signals coming into spinal cord at dorsal root, into dorsal horn–> efferent signals come out of ventral horn

Question 15

What does the dorsal root ganglion contain?

Answer 15

cell bodies of sensory neurons

Question 16

Where are the cell bodies of motor neurons?

Answer 16

ventral horn of spinal cord

Question 17

What is the posterior ramus?

Answer 17

small branch of mixed spinal nerves–> supplies back

Question 18

What are the regions of the spinal cord and how many segments are there in each?

Answer 18

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

Question 19

Where do pairs of nerves emerge from the vertebrae?

Answer 19

intervertebral foramina–> space between 2 vertebrae

Question 20

How does the relationship between nerves and intervertebral foramina change between cervical and thoracic regions?

Answer 20

• nerves C1-C7 emerge above vertebrae
  e.g. C3 comes out between C2 and C3 bones
• whereas nerves C8-Co1 emerge below vertebrae e.g. T11 comes out between T11 and T12 bones
  (bc vertebral column more spread out)

Question 21

What are the spinal cord enlargements?

Answer 21

• cervical enlargement at C5–> innervation of upper limbs
• lumbar enlargement at L2–> innervation of lower limbs
• bc lots of innervation

Question 22

What is the major pathway for voluntary movement (descending)?

Answer 22

corticospinal tract: consists of upper motor neuron (in brain/primary motor cortex) and lower motor neuron (in brainstem and spinal cord)

–> upper motor neuron synapses w/ lower motor neuron

Question 23

What are the major ascending pathways (sensation)?

Answer 23

• dorsal column pathway: for fine touch, vibration and proprioception
• spinothalamic pathway: for pain, crude touch and temperature from skin

Question 24

Where is the primary motor cortex located?

Answer 24

pre-central gyrus (strip in front of central sulcus)

Question 25

What is somatotopy?

Answer 25

where a region of body is represented in the brain e.g. if we stimulate a certain point on brain, a specific part of body moves

Question 26

Where does the corticospinal tract decussate?

Answer 26

in medulla- 85% of fibres cross over to other side (supplying limbs, not trunk)

but synapses in spinal cord

Question 27

What is the corticobulbar tract?

Answer 27

motor from 1y motor cortex to brainstem then to facial muscles

Question 28

Where is the primary somatosensory cortex located?

Answer 28

post-central gyrus

Question 29

What are the 2 parts of the spinothalamic pathway?

Answer 29

anterior spinothalamic tract (pain and temperature) and lateral spinothalamic tract (crude touch)

Question 30

Where are the 3 neurons in the sensory pathways?

Answer 30

• 1y sensory neuron: receptor in skin, cell body in dorsal root
• 2y sensory neuron: cell body in spinal cord for spinothalamic OR medulla for dorsal column–> travels to thalamus
• 3y sensory neuron: cell body in thalamus–> travels to somatosensory cortex

Question 31

At what neuron do the sensory pathways decussate?

Answer 31

at synapse between 1y and 2y sensory neuron

i.e. in medulla or spinal cord

Question 32

What determines the size of somatotopic areas in the post-central gyrus?

Answer 32

the density of sensory receptors in that body region

Question 33

Where does the dorsal column pathway decussate?

Answer 33

medulla

also synapses here

Question 34

Where does the spinothalamic pathway decussate?

Answer 34

spinal cord

also synapses here

Question 35

What are the 2 parts of the corticospinal tract?

Answer 35

lateral (limbs) and anterior (axial muscles)