Cerebral Hemispheres

Question 1

Describe the general features of the cerebrum

Answer 1

Sulcus = dip
Gyrus = elevation
Fissure = larger dip

Gray matter on the surface.
White matter inside.

Basal Ganglia (collection of neuronal cell bodies buried in the white matter)

Lateral ventricle is the cavity in each hemisphere

Question 2

Is the pattern of sulci and gyri variable?

Answer 2

Yes
Change pattern depending on what you use your brain for

Some sulci and gyri are constant features

Question 3

What is the corpus callosum?

Answer 3

Bridges the two cerebral hemispheres

Question 4

What sulci can you see on the cerebrum?

Answer 4

Just above temporal lobe is the lateral sulcus

Joint to this is the central sulcus which runs to the medial surface of the cerebrum

On the medial surface the cingulate sulcus can be seen above the corpus callosum.
The pirate-occipital sulcus can be seen at the back

This divides the brain into frontal, parietal and occipital and temporal lobes

Question 5

What gyri can you see on the cerebrum?

Answer 5

Precentral gyrus:
-Just anterior to central sulcus

Postcentral gyrus:
-Just posterior to central sulcus

Cingulate gyrus:

• Superior to corpus callosum
• Inferior to cingulate sulcus

Question 6

Where is the hippocampus located?

Answer 6

Medial end of temporal lobe which curls into itself

Question 7

What structures are inside the lateral sulcus?

Answer 7

Transverse temporal gyri

Insula

Question 8

What is the difference between different Brodmann Areas?

Answer 8

Each broaden area has a different function and therefore different cellular makeup

Question 9

Describe the functional areas of the cortex

Answer 9

Posterior part of the cerebral hemisphere is sensory while the anterior part is motor.

Medial portions of the cerebral hemisphere (limbic system)
-Storage and retrieval of processed information

Dominant and non-dominant hemisphere for different tasks

There are primary sensory areas and adjacent association areas

Question 10

What does the frontal lobe do?

Answer 10

Motor function

Intellect

Question 11

What does the parietal lobe do?

Answer 11

Somatosensory

Question 12

What does the occipital lobe do?

Answer 12

Vision

Question 13

What does the temporal lobe so?

Answer 13

Hearing and smell

Question 14

What does your Precentral gyrus do?

Answer 14

Area 4: Primary Motor Cortex
(Frontal lobe)

Somatotropic representation of contralateral half of body through motor homunculus

Question 15

What does the inferior frontal gyrus do?

Answer 15

Area 44, 45

Broca’s area of motor speech

Frontal lobe

Question 16

What does the prefrontal cortex do?

Answer 16

Cognitive functions of higher order- intellect, judgement, prediction, planning

Frontal lobe

Question 17

What does the post central gyrus do?

Answer 17

Areas 1, 2, 3
Primary sensory area
(Parietal lobe)

Receives general sensations from contralateral half of body.

Somatotopic representation through sensory homunculus

Question 18

What does the superior parietal lobule do?

Answer 18

Interpretation of general sensory information (sensory association area) and conscious awareness of contralateral half of body

can recognise what you touch

Question 19

What does the inferior parietal lobule do?

Answer 19

Interface between somatosensory cortex and visual and auditory association areas.

IN DOMINANT HEMISPHERE, CONTRIBUTES TO LANGUAGE FUNCTIONS

Question 20

What can a parietal lobe lesion cause?

Answer 20

Hemisensory neglect

Inability to be aware of opposite side of body.

Will not even know that side is there

Question 21

What does the superior temporal gyrus do?

Answer 21

Areas 41, 42
Primary auditory complex
Heschl’s convolusions

Question 22

What are the auditory association areas of the temporal lobe?

Answer 22

Posterior to 41, 42.

In dominant hemisphere -> Wernicke’s area
Crucial for understanding of spoken word.
has connections with other language areas.

Question 23

What does the inferior surface of the temporal lobe do?

Answer 23

Receives fibres from olfactory tract

Conscious appreciation of smell

Question 24

Where is the primary visual cortex?

Answer 24

On the medial surface of the occipital lobe, on either side of the calcimine sulcus is the primary visual cortex
(Area 17)

Question 25

Apart from the primary visual cortex what else does the occipital lobe do?

Answer 25

The rest of the occipital lobe is the visual association cortex concerns with interpretation of visual images. (Areas 18, 19)

Question 26

What is the limbic lobe?

Answer 26

The medial surface of the cerebral hemisphere has areas which together form a functional limbic lobe involved in memory and emotional aspects of behaviour. It includes the cingulate gyrus, the hippocampus (medial aspects of temporal lobe), parahippocampal gyrus and the amygdala (subcortical grey matter close to temporal pole)

Question 27

Describe the language areas of the brain

Answer 27

Broca's area is the motor speech area. Wrenches' area is the auditory association area necessary for recognition of the spoken word. Is in the dominant hemisphere.

Question 28

What is aphasia?

Answer 28

Problem with speech due to damage to one or more speech areas in the brain

Question 29

Describe Broca's aphasia

Answer 29

"Walk Dog" Understands speech Misses small words Aware of difficulties in speech (can't put thoughts into words) Damage to frontal lobe Weakness/paralysis of one side of body

Question 30

Wernicke's aphasia

Answer 30

"You know that smoodle pinkered and that i want to get round him like you want before" Fluent speeach, with new meaningless words, can't understand speech, doesn't know of mistakes Damage to temporal lobe No paralysis

Question 31

There are 3 types of myelinated axon fibres bundles into tracts. What are they?

Answer 31

1. Commisural fibres 2. Association fibres 3. Projection fibres

Question 32

What are commisural fibres?

Answer 32

- Connect corresponding areas of the two hemispheres | - Corpus Callosum

Question 33

What are association fibres?

Answer 33

- Connect 1 part of the cortex with the other (same hemisphere). - They may be short or long

Question 34

What are projection fibres?

Answer 34

Run between the cerebral cortex and various subcortical centres. They pass through the corona radiata and the internal capsule

Question 35

What is the internal capsule?

Answer 35

Made up of projection fibres passing to and from the cerebral cortex It is a narrow area between the thalamus and caudate nucleus medially and the lentiform nucleus laterally. It derives blood supply from the middle cerebral artery and is frequently affected in a stroke

Question 36

Why is an internal capsule stroke so dramatic?

Answer 36

All projection fibres coming from the cerebral cortex to the spinal cord must come through these two channels in the diencephalon. If there is a stroke there will be massive effects to the contralateral side of the body

Question 37

What are the basal ganglia?

Answer 37

Subcortical nuclei (collection of neuronal bodies - grey matter) deep within each cerebral hemisphere. made up of the caudate nucleus, putamen and globes plallidus Substantia nigra in midbrain is functionally part of them though not anatomically

Question 38

What are the individual basal ganglia?

Answer 38

CAUDATE (one with a tail) The PUTAMEN (means the hard shell) GLOBUS PALLIDUS (the pale globe The hard shell + the globe forms a lens like structure - the LENTIFORM NUCLEUS SUBSTANTIAL NIGRA (the black substance, lies in the midbrain!) The SUBTHALAMIC NUCLEII

Question 39

What is the topographical anatomy of the basal ganglia?

Answer 39

The caudate nucleus starts as a large head medial to the internal capsule, a body and a slender curving tail which follows the curve of the lateral ventricle. lateral to the internal capsule is the lentiform nucleus made up of the putamen laterally and globes plaids medially

Question 40

How can you find the lateral ventricle, internal capsule, thalamus and lentiform nucleus on a brain section?

Answer 40

Identify the lateral ventricles and a third ventricle (if present) Lying in the wall of the lateral ventricle is the caudate nucleus Lying beside the third ventricle is the thalamus (diencephalon) lateral to the caudate and thalamus lies the internal capsule lateral to the internal capsule is the lentiform nucleus made up of the globes plaids medially and the putamen laterally

Question 41

What are the connections of the basal ganglia?

Answer 41

1. the caudate nucleus and the putamen are the "input regions" receiving input from the motor cortex, premotor cortex and from thalamus 2. They are in turn connected to the output regions (the globes plaids and substantial nigra) 3. The globes plaids then projects primarily to the thalamus (which in turn sends fibres to motor area of cortex)

Question 42

What does the basal ganglia do?

Answer 42

The major function is to help regulate initiation and termination of movements. Because they play a role in controlling the motor system they are often referred to as the "extrapyramidal system"

Question 43

What is the pathology of the basal ganglia?

Answer 43

Parkinson's Chorea Athetosis etc