Overview of the Brainstem

Question 1

What is the function of the brainstem?

Answer 1

reflexive and unconscious behaviour and modulation of arousal and conscious states

Question 2

What structures make up the brainstem?

Answer 2

the midbrain, pons and medulla

Question 3

What are the rostral and caudal boundaries of the brainstem?

Answer 3

extends rostrally from the mamillary bodies to the pyramidally decussation caudally

Question 4

What can be seen on the dorsal aspect of the brainstem at the level of the midbrain?

Answer 4

the superior and inferior colliculi

Question 5

What can be seen on the dorsal aspect of the brainstem at the level of the pons?

Answer 5

the cerebellum is connected to the brainstem here with the 4th ventricle between the pons and the cerebellum

Question 6

What is on the floor of the 4th ventricle?

Answer 6

the facial colliculi - formed by the abducens nucleus and the fibres of the facial nerve

Question 7

What can be seen on the dorsal aspect of the brainstem at the level of the medulla?

Answer 7

the dorsal columns and the gracile and cuneate tubercles

Question 8

What can be seen on the ventral aspect of the brainstem at the level of the midbrain?

Answer 8

cerebral peduncles

Question 9

What can be seen on the ventral aspect of the brainstem at the level of the pons?

Answer 9

cerebelllar peduncles (superior, middle and inferior)

Question 10

What can be seen on the ventral aspect of the brainstem at the level of the medulla?

Answer 10

inferior olivary nuclei and pyramids descending into the pyramidal decussation

Question 11

What are the important structures located in the brainstem?

Answer 11

cranial nerve nuclei, reticular formation, long fibre tracts and cerebellar circuitry

Question 12

What is the tectum?

Answer 12

the tectum is the roof of the brainstem - the dorsal aspect - it is only found in the midbrain and is made up of the inferior and superior colliculi

Question 13

What is the tegmentum?

Answer 13

the tegmentum is the structure in the brainstem that is continuous with the spinal cord - it is in all part of the brainstem and contains the cranial nerve nuclei and the reticular formation

Question 14

What is the basis?

Answer 14

the basis is the most ventral part of the brainstem located mostly in the pons - it contains the corticospinal fibre tracts and nuclei related to the cerebellum

Question 15

Which cranial nerve does not exit the brainstem ventrally?

Answer 15

IV

Question 16

Which cranial nerves are associated with the brainstem?

Answer 16

III to XII

Question 17

What is the rule of 4s?

Answer 17

4 cranial nerves exit the medulla (IX-XII), 4 cranial nerves exit the pons (V-VIII) and 4 cranial nerves exit above the pons (I-IV)

Question 18

Embryologically, where do sensory nerves develop from?

Answer 18

alar plate

Question 19

Embryologically, where do motor nerves develop from?

Answer 19

basal plate

Question 20

In the brainstem where are motor nuclei located?

Answer 20

close to the midline

Question 21

In the brainstem where are sensory nuclei located?

Answer 21

laterally

Question 22

How are the cranial nerve nuclei organised within the brainstem?

Answer 22

there are 6 columns either side of the midline, the medial 3 are motor and the lateral 3 are sensory. The motor columns are - general somatic motor, brachial motor and general visceral. The sensory columns are - visceral, general somatic and special somatic.

Question 23

What is the function of caudal part of the reticular formation?

Answer 23

survival reflexes and autonomic functions e.g. breathing, heart rate

Question 24

What is the function of the rostral part of the reticular formation?

Answer 24

maintain alert conscious state via modulation of forebrain activity

Question 25

What is the neurotransmitter of the locus coeruleus?

Answer 25

noradrenaline

Question 26

What is the neurotransmitter of the substantia nigra?

Answer 26

dopamine

Question 27

What is the neurotransmitter of the dorsal raphe nucleus?

Answer 27

serotonin

Question 28

What are the 3 major pathways that traverse the brainstem?

Answer 28

dorsal column medial lemniscus pathway (fine touch), anterolateral system (pain), corticospinal tract (movement)

Question 29

Where does the dorsal column medial lemniscus pathway cross the midline?

Answer 29

in the medulla at the medial lemniscus

Question 30

Where does the anterolateral system cross the midline?

Answer 30

in the spinal cord

Question 31

Where does the anterolateral system terminate?

Answer 31

three pathways each terminate in different regions- the thalamus, midbrain and reticular formation

Question 32

Where does the corticospinal tract cross the midline?

Answer 32

the pyramidal decussation

Question 33

What does the dorsal aspect of the brainstem contain?

Answer 33

cranial nerve nuclei and reticular formation

Question 34

What does the ventral aspect of the brainstem contain?

Answer 34

corticospinal tracts, cerebral peduncles, substantia nigra, red nuclei, cerebellar nuclei, cerebellar peduncles, inferior olivary nuclei