basic topography of brain 2

Question 1

what does the medulla continue as and where?

Answer 1

spinal cord at foramen magnum

Question 2

what are the 4 surface features of the medulla?

Answer 2

• Pyramids and their decussation (crossing over)- crossing region of the cortical spinal fibres
• Olives laterally
• Connected to cerebellum by inferior cerebellar peduncle
• Cr N 9, 10, 11 and 12 from its surface

Question 3

what are the cerebellar peduncles?

Answer 3

fibres that connect cerebellum to brainstem

Question 4

how many cerebellar peduncles are there?

Answer 4

3 - superior, middle and inferior

Question 5

where is the grey matter in the cerebrum and cerebellum?

Answer 5

on the surface

Question 6

what is the reticular activating system and where is it found?

Answer 6

co-ordinates wakefulness and sleep-wake transitions through neurons being fired; sits in brainstem

Question 7

what are the 2 surface features of the pons?

Answer 7

• middle cerebellar peduncle
• Cr N 5-8 originate from its surface

Question 8

where does midbrain develop from?

Answer 8

mesencephalon

Question 9

what are the 4 surface features of the midbrain?

Answer 9

• cerebral peduncle
• superior cerebellar peduncle
• origin of trochlear and oculomotor nerves
• corpora quadrigemina (superior and inferior colliculus)

Question 10

label this:

Answer 10

1- Cerebral aqueduct

2- Red nucleus

3- Substantia nigra

4- Superior colliculus

Question 11

where is CSF formed?

Answer 11

by choroid plexus in each ventricle

Question 12

where is CSF absorbed?

Answer 12

by arachnoid villi

Question 13

what are arachnoid villi?

Answer 13

finger like projections of arachnoid membrane that act as one way valves.

Question 14

how do arachnoid villi work in absorbing CSF into venous circulation?

Answer 14

The pressure of the CSF is higher than venous system, so CSF flows through villi and granulations into blood

Question 15

what are the 2 main branches of blood supply of the brain?

Answer 15

• The two Internal Carotid arteries enter the skull through the carotid canal
• The two Vertebral arteries also enter the skull through the foramen magnum to supply the brain.

Question 16

Outline the Circle of Willis

Answer 16

Question 17

what is the circle of willis a protective feature against?

Answer 17

vaso-occlusion of large arteries; even if deficit in one artery, brain will not suffer

Question 18

what happens if there is occlusion in an end artery distal to circle of willis?

Answer 18

no more anastomosis of arteries as they are end arteries, which makes the brain more susceptible to stroke if the occlusion occurs there

Question 19

what are the territories supplied by the cerebral arteries?

Answer 19

• Ant Cerebral arteries- medial surface of cerebral hemisphere
• Middle cerebral- lateral aspect of cerebral hemispheres
• Posterior cerebral- inferior aspect of cerebral hemispheres and occipital Lobe

Question 20

where do superficial and deep veins of the brain drain into?

Answer 20

venous sinuses

Question 21

where do venous sinuses lie?

Answer 21

between 2 layers of dura

Question 22

where do the venous sinuses ultimately drain into?

Answer 22

internal jugular veins

Question 23

what are 5 features of the cerebellum?

Answer 23

1. right and left hemispheres separated by vermis
2. each hemisphere has an anterior, posterior and flocculonodular lobe
3. surface has sulci and folia (instead of being called gyri, are called folia- look like leaf)
4. 3 cerebellar peduncles connect it to brainstem
5. cerebellar tonsils sit just on top of foramen magnum

Question 24

why are the cerebellar tonsils significant?

Answer 24

Sudden changes in intra cranial pressure can cause herniation of them out into foramen magnum

Question 25

what are 2 things the cerebellum controls?

Answer 25

• posture maintenance
• fine tuning motor activity

Question 26

how does info from the pyramidal tracts get to the cerebellum?

Answer 26

via superior cerebellar peduncles

Question 27

what is the abnormality linked with the cerebellum?

Answer 27

ataxia

Question 28

what is ataxia?

Answer 28

lack of voluntary coordination of muscle movements

Question 29

how can you test for ataxia?

Answer 29

1. finger-nose test
2. knee-heel test
3. walking in a straight line