Week 3 Lecture 6: Brainstem and Intro to Cerebellum

Question 1

What is a conduit?

Answer 1

a natural or artificial channel through which something is conveyed e.g fluid

Question 2

What does the reticular formation control?

Answer 2

• consciousness
• cardiovascular and respiratory functions
• perception of pain
• arousal
• sleep wake cycle

Question 3

What is the reticular formation?

Answer 3

diffused area of neurones that spans the whole area of brainstem

Question 4

Which structure in the brain gives rise to cranial nerves 3-12?

Answer 4

brainstem

Question 5

What are the 3 structures that the brainstem is composed of?

Answer 5

midbrain, pons and medulla oblongata

Question 6

What structure sits above the midbrain?

Answer 6

diencephalon

Question 7

What structure is found caudal to the medulla?

Answer 7

spinal cord - at the level of the foramen magnum

Question 8

What is found dorsal and ventral to the brainstem?

Answer 8

dorsal - clivus of the occipital bone

ventral - cerebellum

Question 9

Which components of the brainstem run through the ventricular system?

Answer 9

• IVth ventricle - between the pons and medulla anteriorly and the cerebellum posteriorly
• cerebral aqueduct (Caq) - at the level of the midbrain

Question 10

What is the embryological origin of the structures that make up the brainstem?

Answer 10

mesencephalon (midbrain)

rhombencephalon - metencephalon and myelencephalon (pons and medulla oblongata respectively)

Question 11

What is the internal structure of the brainstem composed of?

Answer 11

1. tectum (most dorsal/ posterior to ventricular system)
2. tegmentum (anterior to ventricular system)
3. basal area (most ventral)

Question 12

In locked in syndrome, how is the patient able to breath?

Answer 12

the stroke is at the level of the pons

the tegmentum is unaffected which explains why patients can breath and CVS is intact

Question 13

What is the junction between the pons and the medulla called?

Answer 13

pontomedullary junction

Question 14

What structure defines the midline of the medulla and seperates the two pyramids?

Answer 14

anterior median fissure

Question 15

What are pyramids (in medulla)?

Answer 15

bumps on either side of the anterior median fissure

underneath is white matter fibres coming from the cortex that are sent down the CNS

Question 16

Where is there crossing over of fibres contained in the medullary pyramids?

Answer 16

decussation of pyramids - this is where fibres from the left and right hemispheres meet so they can instruct the other side of the body

Question 17

What structure separates the pyramids from the olives?

Answer 17

antero-lateral sulcus

Question 18

Which cranial nerve fibres do we find at the antero-lateral sulcus?

Answer 18

hypoglossal nerve

Question 19

Which cranial nerves emerge at the postero-lateral sulcus?

Answer 19

IX (glossopharyngeal), X (vagus), XI (spinal)

Question 20

What is the rhomboid area/ fossa?

Answer 20

floor of the 4th ventricle

Question 21

What two tubercles can we see on the dorsal aspect of the medulla?

Answer 21

1. gracile fasciculus - either side of midline - bump that contains white matter fibres travelling from SC to brainstem
2. cuneate fasciculus (lateral to gracile fasciculus)

Question 22

What is the name of the point that marks the end of the 4th ventricle?

Answer 22

obex

Question 23

How do we divide the medullas?

Answer 23

• rostral or ‘open’ medulla

- caudal or ‘closed’ medulla

Question 24

What are the cuneate and gracile tubercles?

Answer 24

bumps in the gracile fasciculus and cuneate fasciculus because of the nucleis containing cell bodies underlying them

Question 25

What is the defining feature of the open medulla

Answer 25

is open dorsally to the 4th nucleus at the obex

Question 26

Which structures do we find in the closed (caudal) medulla?

Answer 26

- gracile tubercle - cuneate tubercle - pyramid

Question 27

What is the name of the junction between the midbrain and pons?

Answer 27

pontomesencephalic junction

Question 28

Where does the basilar artery sit?

Answer 28

in the basilar groove

Question 29

What is the name of the junction between the cerebellum and the pons?

Answer 29

cerebellopontine angle

Question 30

Which cranial nerves emerge from the cerebellopontine angle?

Answer 30

CN VII and CN VIII - facial and vestibulochochlear

Question 31

What attaches the cerebellum to the midbrain?

Answer 31

superior cerebellar peduncle

Question 32

What attaches the cerebellum to the pons?

Answer 32

middle cerebellar peduncle

Question 33

What attaches the medulla to the cerebellum?

Answer 33

inferior cerebellar peduncle

Question 34

In what direction do the fibres run in the pons?

Answer 34

transverse

Question 35

Which structure forms the roof of the 4th ventricle?

Answer 35

superior cerebellar peduncle

Question 36

What are cerebral peduncles?

Answer 36

a collection of descending motor fibres coming from the cortex

Question 37

What lies in between the left and right cerebral peduncles?

Answer 37

interpeduncular fossa

Question 38

Which cranial nerves emerge from the midbrain?

Answer 38

CN III (from the interpeduncular fossa) and CN IV

Question 39

What are the names of the 2 paired bumps found on the dorsal aspect of the midbrain and what is the significance of each?

Answer 39

superior colliculus - important for the visual system | inferior colliculus - important for the auditory system

Question 40

What is the brachium of the superior colliculus and inferior colliculus?

Answer 40

colliculi have a projection that extends to connect with the thalamus

Question 41

Explain the key features of the anterior view of the midbrain

Answer 41

main feature - cerebral peduncle seperated by interpeduncular fossa oculomotor nerve emerges

Question 42

what are the key features of the dorsal view of the midbrain?

Answer 42

- superior and inferior colliculi - trochlear nerve emerges - has cerebral aquaduct running through it

Question 43

Where is the reticular formation?

Answer 43

in the tegmentum of the brainstem

Question 44

Which arteries are involved in the blood supply to the brainstem?

Answer 44

- PCA (midbrain/ occipital lobe) - basilar artery (pons) - SCA - AICA - PICA - vertebral artery (medulla)

Question 45

State where each of cranial nerve 3-12 emerge from?

Answer 45

3- oculomotor arises between left and right peduncle 5 - trigeminal emerges from middle of pons 6 - abducens in pontomedullary junction 7/8 - facial and vestibulocochlear at level of cerebellar pontine angle 9,10,11 - glossopharyngeal, vagus and accessory emerge lateral to olives 12 - hypoglossal emerges between pyramid and olives

Question 46

What is the cerebellum responsible for?

Answer 46

co ordination of movement, maintenance of balance and posture

Question 47

What is the anatomical location of the cerebellum?

Answer 47

found under the occipital lobes of the cerebral hemispheres and dorsal to brainstem

Question 48

What divides the anterior and posterior lobes of the cerebellum?

Answer 48

primary fissure

Question 49

What seperates the two hemispheres of the cerebellum?

Answer 49

vermis

Question 50

What is tonsillar herniation?

Answer 50

- there are two tonsils seen in the ventral view of the cerebellum, just posterior to the medulla - if there is increased intracranial pressure the tonsils might herniate into the medulla