UNIT 3: brain - external/internal surfaces

Question 1

what is the cortex made of?

Answer 1

six layered sheet of grey matter (clusters of cell bodies/ dendrites)- highly folded to increase surface area

Question 2

what are gyri and sulci?

Answer 2

ridges and grooves

Question 3

what are the main three sulci?

Answer 3

central - splits frontal and parietal lobe
lateral - splits frontal/ parietal from temporal
parieto-occipital - splits parietal from occipital

Question 4

give locations of primary motor, somatosensory, auditory and visual cortex

Answer 4

motor - precentral gyrus (anterior to central sulcus)
somatosensory - postsensory gyrus (posterior to central sulcus)
auditory - upper part of temporal lobe - superior temporal gyrus
visual - medial surface of occipital lobe

Question 5

what are the other areas in the frontal loble?

Answer 5

supplementary/ pre-motor cortex - coordinate motor activity outputted to PMC
pre-frontal cortex - 25% of cortex - involved in decision making, planning of future actions/ emotional & social behaviour

Question 6

what is the difference between the ventral and dorsal stream from the primary visual cortex?

Answer 6

ventral - what? runs on lower temporal cortex- identifies the nature of objects –> fusiform gyrus - identification of faces
dorsal - where? identifies where objects are in space - ends in primary/ secondary motor cortex

Question 7

what is stereognosis and what region of the brain controls it?

Answer 7

ability to detect shape of object by touch & texture - parietal lobe

Question 8

where else does the visual cortex output to and what is it responsible for?

Answer 8

wernicke’s area found in temporal lobe just below lateral sulcus next to primary auditory cortex - only in left hemisphere
- language comprehension and formation of grammatical sentences

Question 9

what are the two other language areas in brain?

Answer 9

supramarginal/angular gyrus - language and number manipulation/ analysis of semantic content
broca’s area - articulation of language - this area connected to wernicke’s area - link between production and interpretation of language

Question 10

what comprises the brainstem?

Answer 10

midbrain, pons, cerebellum and medulla

Question 11

what are the components of the midbrain?

Answer 11

roof -tectum - visual/ auditory reflex centres

floor - tegmentum - cranial nerve nuclei/ dopamine neurones/ ascending & descending pathways

Question 12

what is the significance of substantia nigra?

Answer 12

grey matter where neurons rich in dopamine - axons project to motor areas - loss of nerve cells lead to parkinson’s disease = shuffling gait/ mask-like face/ tremors

Question 13

why is the pons the thickest region of the brainstem?

Answer 13

presence of peduncles (white matter bundles)

• middle peduncle connects the cerebellum
• superior: pathway from cerebellum to cortex
• inferior: spinal cord to cerebellum

Question 14

what does the medulla contain?

Answer 14

systems regulating arousal/ wakefulness
nuclei of cranial nerves
ascending/ descending pathways (to/from spinal cord)

Question 15

what is reticular formation and what is its function?

Answer 15

central core of brain stem - highly interconnected network of short axon neurones

• motor control, extrapyramidal and respiratory centres
• pain modulation
• cardiovascular control
• sleep & consciousness = ARAS - Ascending Reticular Activating System (serotonin/ acetylcholine/ noradrenaline)

Question 16

what can cause damage to ARAS and what does this mean?

Answer 16

epi/subdural haemorrhage or space-filling haemorrhage - cause brainstem compression so forces person into a coma

Question 17

what are the ventricles? describe orientation

Answer 17

cavity filled with CSF produced by choroid plexus
anterior horn - frontal lobe
posterior horn - occipital lobe
body - parietal lobe
inferior horn - temporal lobe

Question 18

describe the ventricular system

Answer 18

lateral ventricles communicate with 3rd ventricle via interventricular foramen - drain through cerebral aqueduct to 4th ventricle
most CSF produced in 4th ventricle which drains through lateral and medial apertures which leads to subarachnoid space surrounding brain & spinal cord

Question 19

what are the functions of the thalamus, hypothalamus and basal ganglia?

Answer 19

thalamus - memory, consciousness, motor control & controlling flow of sensory information
hypothalamus - metabolism, autonomic nervous system, growth/gonadal function, temperature
basal ganglia - control of movement

Question 20

which structures form the basal ganglia?

Answer 20

caudate nucleus / lentiform nucleus (putamen/ globus pallidus) in forebrain
subthalamic nucleus

Question 21

which gland is connected to the thalamus and what is its function?

Answer 21

pineal gland

responsible for circadian rhythms controlled via autonomic nervous system

Question 22

what structures form the limbic system? what functions

Answer 22

amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and cingulate gyrus

• factual/ emotional memory
• reward
• defensive & protective behaviour