9.3 Brainstem

Question 1

What are the 4 cranial nerves above the pons?

Answer 1

1, 2, 3, 4

Question 2

What are the 4 canial nerves attaching to the pons?

Answer 2

5, 6, 7, 8

Question 3

What are the 4 cranial nerves attaching to the medulla?

Answer 3

9, 10, 11, 12

Question 4

What are the 4 medial structures of the brainstem?

Answer 4

Coticospinal tract, medial lemniscus, medial longitudinal fasiculus, motor nucleus (3, 4, 6, 12)

Question 5

What are the 4 lateral structures of the brainstem?

Answer 5

Spinocerebellar tract, spinothalamic, sensory nucleus (5) and sympathetic pathway

Question 6

Where does swallowing, vomiting, ocughing and sneezing get generated and how

Answer 6

In the medulla by the pre motor nuclei innervating CN IX and X

Question 7

Where does chewing get generated and how?

Answer 7

In the pons by the supratrigeminal premotor nucleus

Question 8

Where does conjugate eye movements get generated and how?

Answer 8

Mid brain: by the pre motor nuclei innervating III, IV and VI

Question 9

Where does the locomotor pattern generator occur and how?

Answer 9

In the pons/midbrain: by the pedunco-pontine nucleus and part of the locus coeruleus with input into the reticulospinal tract

Question 10

Where does information about the internal environment get mapped onto?

Answer 10

The solitary nucleus - gets information from 9 and 10

Question 11

Where do pain pathways map onto?

Answer 11

The thalamus, reticular formation, superior colliculus and periaqueductal grey matter

Question 12

Where are the CV and Resp control centres?

Answer 12

Dorsolateral medulla (open medulla)

Question 13

What supplies the pone?

Answer 13

paramedian, short circumferential and long circumferential branches of the basilar artery

Question 14

What would a lesion in the basilar artery cause?

Answer 14

Locked in syndrome

Question 15

What is the general arrangement of inputs to the brainstem?

Answer 15

Motor = medial, sensory = lateral, visceral = intermediate

Question 16

Where is the pyramidal decussation and what occurs here and what will you be able to see?

Answer 16

Where the brainstem (medulla) and the spinal cord meet - corticospinal tracts will cross here
You will be able to see the fasiculus gracilis and cuneatus as well as the nucleus gracilis, you can also see the spinal trigneminal nucleus

Question 17

What occurs at the sensory decussation and what can you see?

Answer 17

Fibres from the DC system will be crossing (nucleus gracilis and cuneatus) to form the medial lemniscus via the internal arcuate fibres
This is where you will start to see the inferior olivary nucleus

Question 18

Why is it termed the open medulla?

Answer 18

The DC fibres have crossed leaving the central canal open dorsally as the 4th ventricle

Question 19

What will you no longer see at the open medulla?

Answer 19

The nucleus gracilis and cuneatus as there fibres have cossed to form the medial lemniscus already

Question 20

What is the new feature you will see at the open medulla?

Answer 20

The fourth ventricle and the inerior cerebellar peduncles

Question 21

Where do fibres from the inferior cerbellar peduncles go from and to?

Answer 21

Fibres from the dorsal cerebellar and cuneo-cerebellar tracts and from the inferior olivary nucleus to the cerebellum

Question 22

What occurs at the level of the pons?

Answer 22

The pontine fibres which have their cell bodies in the pontine nuclei cross the midline and enter the C/L cerebellum through the middle cerebellar peduncle

Question 23

What will you see ventrally at the level of the inferior colliculus?

Answer 23

Substantia nigra and cerebral peduncles

Question 24

What is the main feature at the level of the inferior colliculus?

Answer 24

Crossing of the superior cerebellar peduncles

Question 25

What can you see in the interpeduncular fossa at the level of the infecior colliculus?

Answer 25

CN III

Question 26

What are the new features in the midbrain at the level of he inferior colliculus?

Answer 26

substantia nigra, cerebral aqueduct and cerebral peduncles

Question 27

What is the superior colliculus involved in?

Answer 27

visual reflexes, including a map of visual and somatosensory space

Question 28

What is the new feature at the superior colliculus?

Answer 28

Red nucleus which is the fibres from the crossing of the superior cerebellar peduncles

Question 29

What separates the cerebral peduncles and what are the composed of?

Answer 29

The interpeduncular fossa

Composed of all descending tracts that originate in the cerebral corex

Question 30

What is the function of the reticular formation?

Answer 30

Resp/CV control
Arousal
Control of gate
Autonomic functioning

Question 31

What happens to the NTs in the reticular formation?

Answer 31

They diffuse away from the site to have a greater range of action

Question 32

What are the 3 regions of the reticular formation and what is their role?

Answer 32

Median/Raphe: source of serotenergic system
Paramedian: magnocellular and gigantocellular (efferent) - origin of reticulospinal
Lateral: Parvocellular (efferent) - sensory inputs

Question 33

what is the role of the seratonergic system?

Answer 33

regulating mood and appetite (think SSRI = depression)

Question 34

What is the role of the dopaminergic system and where do the cells originate from?

Answer 34

Initiation of movements, reward system

Originate from: Substantia nigra and ventral tegmental nucleus

Question 35

What is the role of the noradrenergic system and where do the cells originate from?

Answer 35

Regulate attention, arousal and the sleep/wake cycle

Originate from locus coerelus

Question 36

Where do cholinergic cells originate from?

Answer 36

Septal and basal forebrain nuclei and the pontomesencephalotegmental complex

Question 37

What is the function of teh solitary nucleus and tract?

Answer 37

integrate and map sensory information from the internal environment and co-ordinate autonomic output to the brain stem and spinal cord

Question 38

What are the inputs into the solitary nucleus?

Answer 38

VII, IX and X (carrying info from chemoreceptors)