Cerebellum, third and fourth ventricle

Question 1

why is cerebellum the largest part of the hindbrain?

Answer 1

• it accounts for 10% of the brain’s volume

- consists of most the neurons

Question 2

what is the function of cerebellum?

Answer 2

coordination of movement and balance

Question 3

what is the function of vermis?

Answer 3

it joins the two ovoid hemisphere in the midline of the cerebellum

Question 4

what are the peduncles?

Answer 4

it attached the brainstem to each side of cerebellum

Question 5

what is the function of cerebral aqueduct?

Answer 5

it runs through the midbrain and connects the third and fourth ventricles

Question 6

how do you identify these structures?
red nucleus
substantia nigra

Answer 6

red nucleus - a circular mass of grey matter that is ventro lateral to the cerebral aqueduct
substantia nigra - a black band of nerve cells overlying the crus cerebri, ventrolateral to the red nucleus on each side

Question 7

how would you identify the tonsil on cerebellum?

Answer 7

a prominent rounded swelling on cerebellum anteriorly and medially on either side of the vermis

Question 8

what is the significance of flocculo-nodular lobe?

Answer 8

• flocculus (laterally) connected to nodule (medially, below vermis) is called floccular nodular lobe
• it is essential because it concerned with vestibular formation (which is associated with equilibrium)

Question 9

which parts of the BS does the superior, middle and inferior cerebellar peduncles connect with?

Answer 9

superior cerebellar peduncle - connects the cerebellum to midbrain
middle cerebellar peduncle - connects the cerebellum to pons
inferior cerebellar peduncle - connects the cerebellum to medulla oblongata

Question 10

what is the function of spinocerebellar tracts?

Answer 10

spinocerebellar - sensory input for balance and position;

• 2 types: dorsal and ventral
• dorsal spinocerebellar tract - ipsilateral: travels to inferior cerebellar peduncle
• ventral spinocerebellar tract - contralateral: travels to superior cerebellar peduncle

Question 11

what is the function of vestibulocerebellar and corticopontocerebellar tracts?

Answer 11

vestibulocerebellar tract - vestibular impulses from labyrinth directly - travels to the inferior cerebellar peduncle
corticopontocerebellar (rubrothalamic) tract - information from motor cortex of motor plan, the same information goes to spine - travels to the middle cerebellar peduncles

Question 12

which is the largest cerebellar nuclei and what is its function?

Answer 12

• dentate nucleus: most lateral of deep cerebellar nuclei
• zig-zag edged oval mass
• major fibres pass into the superior cerebellar peduncle

Question 13

what is the rhomboid fossa?

Answer 13

it is diamond shaped floor of IVth ventricle limited laterally by cerebral peduncles and posteriorly by gracile and cuneate tubercles

Question 14

what is the function of median sulcus on the floor of IVth ventricle?

Answer 14

divides the rhomboid fossa into triangular left and right halves

Question 15

where to find the following with the respect to the cranial nucleus?

1. vestibular trigone
2. vagal trigone
3. hypoglossal trigone
4. facial collucli

Answer 15

1. vestibular trigone - lateral triangular area overlying the CN8 nucleus
2. vagal trigone - intermediate triangular area overlying the overlying the CN10 nucleus
3. hypoglossal trigone - medial triangular area overlying the CN12 nucleus
4. facial collucli - rounded swelling on pons, the facial nerves passes over it but has the facial nerve nuclei

Question 16

where can you find the obex?

Answer 16

at the inferior apex of rhomboid fossa

Question 17

what is the area posterma? and why is it important?

Answer 17

• a small tongue shaped area anterior-lateral to the obex

- associated with nausea control, a chemoreceptive trigger zone for emetic (vomiting) response

Question 18

what is the function of the following sulcus?

1. central sulcus
2. parieto-occipital sulcus
3. calacrine sulcus

Answer 18

1. central sulcus - separates the frontal and parietal lobe
2. parieto-occipital sulcus - separates the parietal and occipital lobe
3. calcarine sulcus - separates the occipital and temporal lobe

Question 19

what is the function of interventricular foramen?

Answer 19

• allows the CSF flow from lateral ventricles to 3rd ventricle
• it is filled filled with choroid plexus

Question 20

what is corpus callosum? what is the function of corpus callosum?

Answer 20

• it is a broad arched band of white matter

- the largest of fibre bundles connecting the two halves of the brain

Question 21

what are the four main regions of corpus callosum?

Answer 21

1. genu - the anterior curved of CC
2. rostrum - below the genu
3. body - the central part of CC
4. splenium - the posterior rounded end of CC

Question 22

what is fornix and what is its function?

Answer 22

• a bundle of white fibres under the corpus callosum

- connects the hippocampus with the diencephalon and pre-commisural fibres

Question 23

where is thalamus? what is its function?

Answer 23

• at the dorsal part of diencephalon

- major subcortical relay station for information ascending to the cerebral cortex

Question 24

where is hypothalamus?

Answer 24

• at the ventral part of diencephalon

- contributes to the body homeostasis, control the autonomic nervous and neuroendocrine systems

Question 25

what connects different area of the cortex?

Answer 25

myelinated axons

Question 26

what are the main types of fibres and what are its functions?

Answer 26

1. association fibres: links cortical regions in one cerebral hemisphere 2. commissural fibres: links similar function region in two hemisphere e.g. corpus callosum 3. projection fibres: links cortex with subcortical regions such as the thalamus and SC via the internal capsule and corona radiata

Question 27

what are the two basic functions of cerebral hemisphere?

Answer 27

1. to bring together the separate representations of two halves of the brain, the visual and auditory system 2. to unite areas of cortex which have functions specialised to one hemisphere

Question 28

which one is dominant hemisphere and what is it responsible for?

Answer 28

left hemisphere is dominant and is responsible for language | right hemisphere is non-dominant

Question 29

what happens if the corpus callosum is damaged?

Answer 29

- this would demonstrate sperry split brain phenomenon - each hemisphere would behave autonomously - lack of cross integration where the second hemisphere does not know hat the first hemisphere is doing - for e.g. if a reading and naming stimuli is presented to the left visual field, the individual are unable to read/write/name as this would be directed to the right hemisphere (non-dominant) which does not evoke a verbal response

Question 30

what is the function of superior and inferior collucli?

Answer 30

superior collucli - visual system through lateral geniculate body inferior collucli - auditory system through medial geniculate body

Question 31

what is the difference between primary fissure and horizontal fissure?

Answer 31

primary fissure - seperates anterior lobe and posterior lobe | horizontal fissure - seperates middle and posterior lobe

Question 32

how to identify the following? 1. basilar sulcus 2. bulbopontine sulcus 3. anterior median fissure 4. pyramids 5. olive

Answer 32

1. basilar sulcus - on the midline of pons 2. bulbopontine sulcus - junction b/w pons and medulla 3. anterior median fissure - divides the medulla 4. pyramids - medially 5. olive - laterally

Question 33

how to identify the gracile and cuneate tubercles?

Answer 33

- below the rhomboid fossa - dorsal column nuclei, involved in medial lemniscus pathway - gracile tubercle - medial, lower limbs - cuneate tubercle - lateral, upper limb

Question 34

what is the significance of medullary striae?

Answer 34

divide the floor of ventricle into rostral pontine half and caudal medullary half

Question 35

where is locus coerulus? and what is its function?

Answer 35

- behind rostral pons | - function: produces NA - stress response + arousal

Question 36

where to identify the anterior commissure?

Answer 36

below the anterior end of fornix

Question 37

Outline the pathway of CSF flow

Answer 37

Lateral ventricle -> interventricular foramen (foramen of munroe) -> third ventricle -> cerebral aqueduct -> fourth ventricle -> central canal -> subarchanoid space

Question 38

where is the crus cerebri?

Answer 38

anterior portion of cerebral peduncle contains the motor tracts, travelling from cerebral cortex to pons and spine

Question 39

where to identify the anterior and posterior commissure?

Answer 39

anterior commissure - in front (anterior) of the columns of fornix, connects the two hemisphere posterior commissure - below the fornix in the third ventricle