Anatomy and function of cerebral hemispheres*

Question 1

Explain the structure of the cerebral hemispheres?

Answer 1

It is highly folden so that it has a large surface area can be packed into a small space. It contains a rim of grey matter and a core of white matter.

Question 2

What are the clefs separating each area in the cerebral hemispheres called?

Answer 2

Sulci.

Question 3

What are the raised separating each area in the cerebral hemispheres called?

Answer 3

Gyri.

Question 4

What does the cerebral cortex consist of?

Answer 4

Neuronal cell bodies, dendrites and synapses. There is a mass of nerve fibres beneath the cortical surface.

Question 5

What is in the white matter of the cerebral cortex?

Answer 5

It consists of axons bundled together as tracts running in three directions.

Question 6

What are the three tracts (fibre types) ?

Answer 6

• Association fibres connect different areas in the same hemisphere.
• Commissural fibres - linking left and right hemispheres.
• Projection fibres - connect cortex with other areas of the CNS to motor/sensory tracts.

Question 7

Where does auditory stimuli project?

Answer 7

To the auditory cortex in the temporal lobe.

Question 8

Where does the visual stimuli project?

Answer 8

To the visual cortex in the occipital.

Question 9

Where does the somatosensory stimuli project?

Answer 9

To the somatosensory cortex in the parietal lobe.

Question 10

What happens if the motor cortex is damaged or diseased?

Answer 10

It will produce spastic paralysis of the contralateral muscles controlled by the area of the cortex affected and hyperflexia of the muscles.

Question 11

What happens if the sensory cortex is damaged or diseased?

Answer 11

Produces loss of sensation (anaesthesia) from corresponding part of body projecting to the damaged or diseased area of cortex.

Question 12

What do the areas of cortex outside the primary areas do?

Answer 12

The rest of the cortex is designated as the association cortex (rather than language processing).

Question 13

What do secondary association areas do?

Answer 13

They integrate signals received in the primary areas.

Question 14

What is the prefrontal association cortex concerned with?

Answer 14

Mood and personality.

Question 15

What is the prefrontal association cortex concerned with?

Answer 15

Mood and personality.

Question 16

What happens if the prefrontal association cortex is damaged?

Answer 16

Patients may:
- have a short attention span
- unaware of turn-taking
- ignore questions
- aggressive
- sensory neglect of their interpersonal space.
- puerile jocularity - laughing inappropriately
- inability to understand complex ideas.

Question 17

What is broca’s area involved in? and what if it is damaged?

Answer 17

• language execution
• damage causes brocas aphasia with few words.

Question 18

What is wernicke’s area involved in? and what if it is damaged?

Answer 18

• Language comprehension.
• Being unable to understand or reply meaningfully.

Question 19

What happens if the parietal cortex is damaged?

Answer 19

It will effect clients skills and behaviour but is dependent on which side of brain is affected because of laterality of function.

Question 20

What does the left hemisphere deal with?

Answer 20

Symbolic function - logic, language, maths.

Question 21

What does the right hemisphere deal with?

Answer 21

Visuospatial function - facial recognition, artistic ability, pattern recognition, 3D problems.

Question 22

What happens if the posterior association cortex is damaged?

Answer 22

It can cause:
- apraxia - inability to make functional movements when motor systems are still intact.

• agnosia - inability to interpret sensory information although the relevant sensory systems are intact.

Question 23

What happens if the left parietal cortex is damaged?

Answer 23

Left-right confusion.
Alexia – impairment of reading.
Agraphia – impairment of writing ability.
Anomia – inability to name objects

Question 24

What happens if the right parietal cortex is damaged?

Answer 24

Sensory inattention to the left side of the environment.

Dressing apraxia – inability to dress properly especially obvious on the left side of the body.

Constructional apraxia – inability to draw simple figures and shapes.