Cerebral Hemispheres

Question 1

What are the grooves and elevations which cover the brain called?

Answer 1

sulcus= dips 
gurus= elevations 
fissures= larger dips

Question 2

What separates and connects the 2 cerebral hemispheres?

Answer 2

the median longitudinal fissure but about 2-3cm down there is a bridge between the 2 hemispheres called the corpus callosum

Question 3

What separates the frontal and parietal lobes?

Answer 3

the central sulcus

Question 4

what separates the parietal and occipital lobes?

Answer 4

parieto-occipital sulcus which can be seen medially

Question 5

What separates the frontal and parietal lobes from the temporal lobes?

Answer 5

the lateral sulcus

Question 6

what are the sulcus and gyrus that are seen only medially and just superior to the corpus callosum?

Answer 6

the cingulate sulcus and gyrus

Question 7

what can be found on either side of the central gyrus?

Answer 7

the pre and post central gyrus

Question 8

what is the frontal lobe divided into anterior to the precentral gyrus?

Answer 8

superior, middle and inferior frontal gyrus

Question 9

what can the parietal lobe be spilt into?

Answer 9

the superior and inferior parietal lobules

Question 10

what can the temporal lobe be spilt into?

Answer 10

superior, middle and inferior temporal gyri

Question 11

what is cortical mapping?

Answer 11

52 different histological areas of the cortex which all have different functions= Brodmann Areas

Question 12

What are the general rules of the brain?

Answer 12

the frontal lobe is motor and the other lobes are all sensory
you have a dominant and non-dominant hemisphere which decides left or right handedness (for most activities both can perform the tasks equally but the dominant takes over and performs the task)

Question 13

Where is and what is the the limbic system?

Answer 13

it is the medial portions of the cerebral hemispheres which together form a functional limbic lobe involved in memory and emotional behaviours - it includes the cingulate gyrus, hippocampus (medial part of the temporal lobe), parahippocampal gyrus and amygdala (subcortical grey matter close to temporal pole)

Question 14

what can we see if we pull the lateral sulcus apart?

Answer 14

gyrus going towards the hidden part of the brain called the insula= transverse temporal gyrus

Question 15

Explain primary sensory areas and adjacent association areas.

Answer 15

primary sensory areas receive the sensory information and then pass this information to the association areas to make sense of the information

Question 16

Describe the precentral gyrus.

Answer 16

frontal lobe, area 4, primary motor cortex - somatotopic representation of contralateral half of body (the left precentral gyrus takes care of the right side of the body and the areas of the body are represented not by its actual proportional size but proportional to the amount of muscular activity and fine muscular activity involved= motor homunculus)

Question 17

Describe the prefrontal cortex.

Answer 17

frontal lobe, areas 6 & 8 make sense of cognitive functions of higher order-intellect, judgement, prediction, planning and orders area 4 to contract specific muscles and the specific sequence in which they should be activated to produce the desired movement

Question 18

Explain the inferior frontal gyrus.

Answer 18

frontal lobe, area 44 and 45= Broca’s area of motor speech- when you have an idea this makes it into words and sentences and let’s this part of your prefrontal know that what comes out of your mouth is coherent words in the specified language you’re speaking in

Question 19

Explain the post-central gyrus.

Answer 19

parietal lobe, areas 3,1,2, primary sensory area - somatotopic representation of the contralateral half of the body= sensory homunculus

Question 20

Explain the superior parietal lobule.

Answer 20

parietal lobe just behind 3,1,2 - sensory association area= interpretation of general sensory information and conscious awareness of contralateral half of body

Question 21

Explain the inferior parietal lobule.

Answer 21

interface between the somatosensory cortex and visual and auditory association areas- in the dominant hemisphere it contributes to language functions

Question 22

what would a parietal lobe lesion cause?

Answer 22

hemisensory neglect ie lesion in left parietal lobe affecting the superior parietal lobule, patient would ignore the right side of their body eg on copy left side of a diagram

Question 23

what is the temporal lobe responsive for?

Answer 23

hearing and smell

Question 24

explain the superior temporal gyrus.

Answer 24

primary auditory cortex, areas 41 & 42 also Heschl’s convolutions

Question 25

Explain the auditory association areas.

Answer 25

posterior to 41 and 42 and in the dominant hemisphere are called Wernicke’s area which helps decipher speech but in both is crucial for understanding of spoken word

Question 26

What does the inferior surface of the temporal lobe do?

Answer 26

receives fibres from the olfactory tract= conscious appreciation of smell

Question 27

what is found on the medial surface of the occipital lobe?

Answer 27

on either side of the calcarine sulcus is the primary visual cortex= area 17

Question 28

what is the rest of the occipital lobe responsible for?

Answer 28

it is the visual association cortex= areas 18 and 19 which interpret visual images

Question 29

What is aphasia?

Answer 29

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

Question 30

What are the language areas in the brain?

Answer 30

Broca’s areas= motor speech area
Precentral gyrus= motor control of mouth and lips= bilateral
Wernicke’s area= auditory association area necessary for recognition of the spoken word and is in the dominant hemisphere

Question 31

What would Broca’s aphasia cause?

Answer 31

he understands the question/speech as sensory area is fine, prefrontal cortex tells him what to reply but due to lesions in the Broca’s area he is unable to make coherent speech and misses small words but is aware of difficulties in speech - normally associated with someone weakness or paralysis of one side of the body

Question 32

What would Wernicke’s aphasia look like?

Answer 32

only in the dominant lobe- speech is fluent but has new meaningless words, he can’t understand speech and doesn’t know of mistakes- no paralysis associated

Question 33

what are the 3 types of white matter tracts?

Answer 33

commissural fibres, association fibres and projection fibres

Question 34

What are commissural fibres?

Answer 34

connect corresponding areas of the 2 hemispheres so that they can talk to each other about what they are doing - the largest of which is the corpus callosum

Question 35

What are association fibres?

Answer 35

connect one part of the cortex with another- eg connecting lobes or primary and association areas

Question 36

What are projection fibres?

Answer 36

run between the cerebral cortex and various subcortical centres like the brainstem and spinal cord to the muscles and they pass through the internal capsule and then radiate out to the different hemispheres in a radiating bunch of fibres called the corona radiata

Question 37

What is the internal capsule?

Answer 37

projection fibres passing to and from the cerebral cortex and is a narrow area between the thalamus and caudate nucleus medially and lentiform nucleus laterally blood supply from MCA and frequently affected in a stroke

Question 38

What are the basal ganglia?

Answer 38

subcortical nuclei (collection of neuronal cell bodies- grey matter) deep within each cerebral hemisphere- made up of the caudate nucleus, putamen and globus pallidus- the substantia nigra in the is functionally part of them but not anatomically - the caudate nucleus and putamen are input regions and feed this to the globes pallidus and substantia nigra which then project to the thalamus

Question 39

What is the role of the basal ganglia?

Answer 39

regulate initiation and termination of movements