Topography the Brain

Question 1

Some main regions of the brain:

Answer 1

Cerebrum (two hemispheres) Diencephalon (contains thalamus and hypothalamus) Brainstem (Midbrain - Pons - Medulla) Cerebellum

Question 2

Where are the ventricles found in the brain?

Answer 2

2 Lateral Ventricles are found within the cerebral hemispheres The 3rd ventricle is found within the diencephalon The cerebral aqueduct is contained within the midbrain The 4th Ventricle is post to the pons & medulla and anterior to the cerebellum

Question 3

What is contained within the ventricles?

Answer 3

CSF

Question 4

Where is CSF made, travel and absorbed

Answer 4

• Produced in choroid plexus of ventricles - Passes into subarachnoid space through foramina in the roof of the 4th ventricle - Absorbed by arachnoid villi - Passes into the sagittal sinus

Question 5

What arteries supply the brain?

Answer 5

The ICAs & Vertebral Arteries

Question 6

What is the function of the circle of willis and what arteries feed into it?

Answer 6

The circle of willis compensates for one vessel to the brain being blocked by allowing others to supply the same area. Its fed by the two ICAs and the basilar artery (which is made by the 2 vertebral arteries)

Question 7

What major vessels come off the circle of willis?

Answer 7

Anterior Cerebral Artery Middle Cerebral Artery Posterior Cerebral artery Its worth noting there is no more anastomosis after the circle of willis (they are end arteries), so any blockage in this arteries or their branches will cause ischaemic stroke

Question 8

Which artery supplies which part of the brain?

Answer 8

Brainstem - Basilar Art Cerebellum - Basilar Art Cerebrum: - Ant Cerebral Art supplies the medial aspect - Middle Cerebral Art Supplies the lateral aspect - Posterior cerebral Art supplies the occipital lobe and much of the inferior aspect

Question 9

Describe the venous drainage of the brain?

Answer 9

Superficial veins -> Deep Veins -> Venous Sinuses -> Internal Jugulars

Question 10

Where do the venous sinuses lie?

Answer 10

Between layers of dura mater (Dura mater is two layers its just they’re always fused except at venous sinuses)

Question 11

What are the major venous sinuses of the brain?

Answer 11

Cavernous sinus Superior & Inf Sagittal Sinuses Transverse Sinus Straight Sinus Sigmoid Sinus Sup & Inf Petrosal Sinuses Can you locate them all?

Question 12

Where is the cavernous sinus?

Answer 12

Between the sphenoid and temporal bones. Basically just under/lateral to the sella turcica

Question 13

Where is the transverse sinus?

Answer 13

Runs in a transverse plane against the inf surface of the occipital bone

Question 14

Where is the sigmoid sinus?

Answer 14

Curves in an S shape behind the petrous temporal bone. It drains from the transverse sinus and becomes the IJV at the jugular foramen

Question 15

What cranial nerves are given off by the brainstem?

Answer 15

III –> XII

Question 16

What is the function of the brainstem?

Answer 16

• Give off cranial nerve 3-12 - Pathway for tracts running from higher brain centres - Contains vital centres (Respiratory, cardiovascular)

Question 17

How is the brainstem attached to the cerebellum?

Answer 17

By the Cerebellar Peduncle which is split into 3: - Meddulla = Inf Cerebral Peduncle - Pons = Middle Cerebral Peduncle - Midbrain = Sup Cerebral Peduncle

Question 18

Which section of the brainstem gives out which cranial nerves?

Answer 18

Higher the brainstem lower the cranial nerve. Midbrain - 3 & 4 Pons - 5 –> 8 Medulla - 9 –> 12

Question 19

What are the important surface features of the medulla?

Answer 19

Pyramidal projections run down the front of the medulla, they are motor fibre tracts. The olives lateral to the pyramids at the top of the medulla

Question 20

What happens to the medullla’s pyramids near the bottom?

Answer 20

Near the bottom of the medulla the pyramids cross over. This is called the Decussation of the Pyramids

Question 21

What ventricle is related to the brainstem?

Answer 21

TWO! Midbrain contains the cerebral aqueduct The pons & medulla are ant to the 4th ventricle

Question 22

Which cranial nerve is the only one to originate posteriorly?

Answer 22

The 4th (Trochlear) from the midbrain

Question 23

What is the important surface anatomy of the midbrain?

Answer 23

Posteriorly you can see the sup & Inf Colliculi which are involved in the visual and auditory reflex

Question 24

Function of the cerebellum?

Answer 24

Co-ordination and movement

Question 25

Function of the Diencephalon?

Answer 25

Thalamus - Acts as a sensory relay centre Hypothalamus - Involved in regulating the ANS, hormones, temperature and circadian rhythm

Question 26

What makes up the Diencephalon?

Answer 26

A number of paired structures: - Thalamus - Hypothalamus - Pituitary - Epithalamus (pineal Gland)

Question 27

Whats the function/location of the thalamus

Answer 27

Its egg shaped on either side of the 3rd ventricle Made up of ant/medial/lateral nuclei groups Acts as a sensory relay station

Question 28

Whats the function of the hypothalamus?

Answer 28

Below thalamus separated by the hypothalamic sulcus Its essential for homeostasis: - Controls the autonomic system - Regulates body temp - Regulates hunger and thirst - Regulates sleep-wake cycle - Controls the endocrine system

Question 29

Describe the structure of the cerebellum? - Lobes - Surface - Connections to rest of brain

Answer 29

• Two hemispheres connected by a vermis - Each hemisphere is split into ant/post/flocculonodular lobe - Surface covered in sulci & Folia (Gyri) - Connected to brainstem by inf/middle/sup cerebellar peduncles - Undersurface has attached cerebellar tonsils

Question 30

Whats the function of the cerebellum?

Answer 30

It gets info on proprioception, balance, posture and from the brain motor intention Then it works out force, direction, extent of contraction to ensure smooth coordinated movement while maintaining posture and feeds it back to the cerebral cortex. I.e. it fine tunes movement and maintains posture

Question 31

What happens if theres damage to the cerebellum?

Answer 31

Ataxia - A lack of smooth voluntary muscle contraction So the person can still make movements but without fine control so cant do: - Finger Nose test - Knee Heel Test - Walking in a straight line

Question 32

What connects the brainstem and the cerebrum?

Answer 32

The midbrain includes the cerebral peduncles which connect the pons to the thalami (and through that to the cerebrum)

Question 33

What vessels come off the basilar artery?

Answer 33

Cerebellar The Superior cerebellar and Anterior Inferior Cerebellar come of the Basilar itself The Posterior Inferior comes off the vertebral arteries prior to fusing to form the basilar artery

Question 34

What is found in the white matter/ grey matter of the medulla

Answer 34

white matter: -pyrimidal tracts -Inferior peduncle -Medial lemniscus Grey matter: -Cranial nuclei -nuclei of reticular formation -sensory nuclei -Olivary nerve nucleus

Question 35

what is found in the white/ grey matter of the pons

Answer 35

white: -middle cerebellar peduncle -medial lemniscus -pyrimidal tracts Grey: -Cranial nerve nuclei -pontine nuclei -nuclei of reticular formation

Question 36

Answer 36

1- Middle cerebellar peduncle

2- Medial lemniscus

3- pyramidal tract

Grey matter

A- cranial nerve nuclei

B- Pontine nuclei

C- nuclei of reticular formation

Question 37

Answer 37

1- pyrimidal tracty

2- medial lemniscus

Question 38

Answer 38

3- inferior cerebellar peduncle