Brainstem

Question 1

What are the functions of brainstem?

Answer 1

reflexive and unconscious behaviour (for survival)

modulation of various arousal and conscious states

Question 2

What are the components of brainstem?

Answer 2

mid brain, pons, medulla, oblongata

Question 3

Where is the brainstem located? How far does it extend?

Answer 3

in the posterior cranial fossa

extends from Mammillary bodies to the pyramidal decussation

Question 4

What are the surface structures of midbrain, both anteriorly and posteriorly

Answer 4

anterior: cerebral peduncles (contains pyramidal tracts from cortex)
posterior: superior and inferior pairs of colliculi (for eye movement control and hearing)

Question 5

Where is the connection between cerebellum to brainstem?

Answer 5

Pons, via cerebellar peduncles

Question 6

where is the facial colliculi? what are they formed by?

Answer 6

along the floor of the 4th ventricle, between pons and cerebellum

formed by abducens nucleus and fibres of CNVII

Question 7

What’s located on the dorsal aspect of medulla?

Answer 7

dorsal columns and nuclei-gracile and cuneate tubercle

Question 8

what’s located on the ventral aspect of medulla?

Answer 8

two bulges of inferior olivary nuclei (superior) and pyramidal decussation (posterior)

Question 9

Where is the tectum?

Answer 9

the roof of the midbrain

Question 10

where is the tegmentum

Answer 10

ventral to the ventricular system, running all the way from brainstem to the spinal cord

Question 11

What does the tegmentum cover?

Answer 11

cranial nerves, reticular formation

Question 12

What is the midbrain important for?

Answer 12

it contains important descending motor tracts (corticospinal)
it has a range of nuclei modulating the descending motor fibres

Question 13

What are the pathology associated with midbrain damage both 1) ventrally 2) dorsally

Answer 13

1) tectum and tegmentum are located ventrally, damage can cause major problem with movement
2) cranial nuclei are located dorsally, so damage will cause cranial nerve deficit

Question 14

Do cranial nerves exit the brainstem in order?

Answer 14

Yes, CNIII most rostrally, CNXII most caudally

Question 15

which cranial nerves are mix nerves

Answer 15

trigeminal, facial, glossopharyngeal, vagus

Question 16

which CNs exit the medulla?

Answer 16

glossopharyngeal, vagus, accessory, hypoglossal

Question 17

which CNs exit the pons?

Answer 17

trigem, abducent, facial, vestibulocochlear

Question 18

which CNs exit above the pons?

Answer 18

olfactory, optic, oculomotor, trochlear

Question 19

Embryologically, where are 1) motor nuclei 2) sensory nuclei developed?

Answer 19

1) basal plate

2) Alar plate

Question 20

Which embryological plate shifts laterally? Why does it shift?

Answer 20

alar plate

because the ventricles are in the way

Question 21

How are nuclei of the CN placed in the brainstem?

Answer 21

in columns

Question 22

What is the significance of alar plate shift?

Answer 22

CN sensory nuclei are positioned laterally, whereas motor nuclei are towards the midline

Question 23

What are the three types of brainstem motor nuclei?

Answer 23

general somatic motor
branchial motor
general visceral

Question 24

What happens when the inferior cerebral peduncle is damaged?

Answer 24

peduncle contains projection to cerebellum, so any damage can lead to ataxia (clumsiness)

Question 25

What are the three types of brainstem sensory nuclei?

Answer 25

general sensory
visceral sensory
special sensory

Question 26

Which CN nuclei are located in the midbrain?

Answer 26

oculomotor and trochlea

they are both pure motor nerves, so are located medially

Question 27

Where can you find reticular formation?

Answer 27

within the tegmentum, which extends rostrally with thalamus, through the brainstem, and continuous with gray of spinal cord

Question 28

What is the function of reticular formation rostrally

Answer 28

in the midbrain and upper pons, they maintain alert conscious state

Question 29

What is the function of reticular formation caudally

Answer 29

working with CN and spinal cord to carry out survival reflex like breathing and control of heart rate

Question 30

How does the reticular formation modulate the forebrain?

Answer 30

the rostral RF provides long ascending tracts that release different neurotransmitters to modulate the forebrain

Question 31

What is the function of ventrolateral medullary reticular formation (VMRF)

Answer 31

regulate vagus functions such as GI response (swallowing, vomiting), respiratory activities, CV response

Question 32

What are the three long fibre tracts?

Answer 32

dorsal column medial leminiscus system
anterolateral system
corticospinal tract

Question 33

Where do the three long fibre tracts decussate?

Answer 33

dorsal column - dorsal medulla
anterolateral system - spinal cord
corticospinal tract - pyramidal decussation at ventral oblongata