Brain & Motor Pathways

Question 1

where is the central sulcus and what sits here

Answer 1

separates the frontal and parietal lobes of the brain. pre central gyrus - motor cortex and speech
post central gyrus - somatosensory cortex

Question 2

what does the lateral fissure split and what lies deep to this

Answer 2

frontal and parietal from temporal. auditory cortex sits here in temporal - also wernickes area for understanding speech

Question 3

where is the visual cortex

Answer 3

medial side of occipital lobe

Question 4

what is the role of the corpus callosum

Answer 4

communication between two hemispheres

Question 5

where do fibres go once they leave the motor cortex

Answer 5

through the corona radiata - white matter in the brain - myelinated axons - then through internal capsule

Question 6

what is the internal capsule and where does it sit

Answer 6

white matter where fibres can pass through - between lentiform nucleus and thalamus - grey matters deep in brain

Question 7

how are the ventricles in the brain connected

Answer 7

lateral ventricle - large ventricle where CSF is formed. Passes to 3rd ventricle via interventricular foramen then leaves 3rd ventricle into 4th ventricle through the cerebral aqueduct

Question 8

how is the motor cortex and somatoaesthetic cortex arranged

Answer 8

arranged depending on distribution of nerve fibres. those with fine motor control have a larger represenation, those that are highly sensitive have a large representation - somatotopic localisation

Question 9

what cranial nerves leave some of their fibres on the same side

Answer 9

oculomotor, trochlear, trigeminal, abducens, glossopharyngeal, accessory, vagus

Question 10

what cranial nerves cross all their fibres to the other side

Answer 10

hypoglossal nerve

Question 11

what happens with the facial nerve fibres

Answer 11

some of the facial nerve fibres remain on the same side - tend to be upper facial nerves that supply forehead.

Question 12

what would be the result of a blockage at the internal capsule

Answer 12

fibres on this affected side would be unable to run therefore would not cross over. however, the fibres on the other side would cross over and stay on that side - 3,4,5,6,9,10,11 would be fine. however, hypoglossal nerve and facial nerve would not. would result in paralyses of tongue muscles on the opposite side, and lower facial paralyses

Question 13

what blood vessel is involved in supplying the internal capsule, and would therefore be damaged or blocked

Answer 13

leticulostratic arteries - coming off middle cerebral arteries

Question 14

what is the distribution of ganglia of cranial nerves in brainstem

Answer 14

those formed from somites are paired near the midline - 1,2,3,4,6. those from pharyngeal arch are more lateral - 5th and 7th. nucleus ambiguous forms from 9th 10th and 11th CN

Question 15

describe the circle of willis

Answer 15

right and left vertebral arteries join to make basilar artery. this then splits into right and left posterior cerebral arteries. the internal carotid artery gives rise to anterior and middle cerebral arteries. anterior and posterior right and left communicating arteries also formed so all arteries join

Question 16

if a patient presents with a paralysed face, tongue, upper and lower limb what would you think

Answer 16

blockage at internal capsule - leticulostratic arteries from middle cerebral

Question 17

if a patient persents with a paralysed face, upper limb and difficulty speaking what would u think

Answer 17

blockage of middle cerebral artery - lower spared due to supply from anterior cerebral

Question 18

how do you know the trochlear, oculomotor and abducens nerves are working

Answer 18

patient doesnt have a squint - if they werent working they would be squinting

Question 19

what is hydrocephalus

Answer 19

water in the brain, cerebral aqueduct blocked preventing drainage of 3rd ventricle into 4th ventricle, causing swelling