Overview of Brainstem Organisation

Question 1

What is the gateway between the spinal cord and higher cortical areas?

Answer 1

Brainstem

Question 2

What are the two major functions of the brainstem?

Answer 2

Reflexive and unconscious behaviour

Modulation of various arousal and conscious states

Question 3

Where is the brainstem located?

Answer 3

In the posterior cranial fossa, extending from the mammillary bodies to the pyramidal decussation caudally.

Question 4

What are the 3 divisions of the brainstem?

Answer 4

Midbrain, pons and medulla

Question 5

What are the two pairs of characteristic bumps on the dorsal aspect of the midbrain?

Answer 5

The superior and inferior colliculi

Question 6

Which part of the brainstem does the cerebellum attach to?

Answer 6

Pons

Question 7

What is the pons limited by?

Answer 7

The 4th ventricle

Question 8

Which parts of the pons form the floor of the 4th ventricle?

Answer 8

The facial colliculi

Question 9

What forms the facial colliculi

Answer 9

Abducens nucleus and fibres of CNVII (facial nerve)

Question 10

What forms the dorsal aspect of the caudal medulla?

Answer 10

Dorsal columns and nuclei, forming the gracile and cuneate tubercles

Question 11

What can be seen on the ventral aspect of the midbrain?

Answer 11

Cerebral peduncles with the interpeduncular fossa in between.

Question 12

What can be seen on the ventral aspect of the pons?

Answer 12

The superior, middle and inferior cerebellar peduncles dorsolaterally attaching to the cerebellum.

Question 13

What can be seen on the ventral aspect of the medulla?

Answer 13

Rostral: Inferior olivary nuclei

Pyramids descending to the pyramidal decussation

Question 14

What is the tectum?

Answer 14

The “roof” of the midbrain - the dorsal part. It refers solely to the colliculi of the midbrain.

Question 15

What forms the roof of the 4th ventricle?

Answer 15

The 4 colliculi, i.e. the tectum.

Question 16

What is the tegmentum?

Answer 16

Where the spinal cord continues up into the brainstem - continous with the spinal cord.

Structures within the tegmentum go to the spinal cord.

These include the cranial nerves and reticular formation.

Question 17

What is the basis?

Answer 17

The basillar pons - the anterior portion of the pons.

Important for descending motor control, e.g. attachments to cerebellum, from cerebellum to other nuclei and tracts important for motor systems.

Question 18

Which part of the brainstem only applies to the colliculi and midbrain?

Answer 18

The tectum

Question 19

Which part of the brainstem is a continuation of the spinal cord that travels throughout the entire brainstem?

Answer 19

Tegmentum

Question 20

What does the tegmentum occupy?

Answer 20

Middle part of the midbrain

Dorsal part of the pons and medulla

Question 21

What does the tegmentum contain?

Answer 21

Nuclei for the cranial nerves and the reticular formation.

Question 22

What is the sole focus of the basis?

Answer 22

Motor control

Question 23

Where do the spinal nerves end?

Answer 23

C2

Question 24

Which spinal cord segment lacks a dermatome?

Answer 24

C1

Question 25

What do the spinal nerves supply?

Answer 25

The body

Question 26

What do the cranial nerves supply?

Answer 26

Somatic and visceral motor and sensory information to head

Question 27

Which cranial nerves also supply visceral sensory and motor innervation to neck, chest and most abdominal organs?

Answer 27

CNIX and X

Question 28

Which side of the brainstem do most cranial nerves exit?

Answer 28

Ventral

Question 29

Which cranial nerve does not exit the brainstem on the ventral surface?

Answer 29

CNIV

Question 30

Which cranial nerves are exclusively motor?

Answer 30

CNIII, IV and VI (control the eye) CNXI and XII

Question 31

Which cranial nerves are exclusively sensory?

Answer 31

CNI, II and VIII

Question 32

Which cranial nerves are mixed?

Answer 32

CNV, VII, IX and X

Question 33

What is the rule of 4 for the cranial nerves?

Answer 33

4 cranial nerves exit the medulla: CNIX-XII 4 exit the pons: CNV, VI, VII, VIII 4 exit above the pons: CNIII, IV

Question 34

Where do the cranial nerve nuclei lie during embryological development?

Answer 34

Adjacent to the ventricular system

Question 35

Which plate do the sensory nuclei develop from?

Answer 35

Alar plate

Question 36

Which plate do the motor nuclei develop from?

Answer 36

Basal plate

Question 37

How are the positions of the cranial nerve nuclei determined?

Answer 37

As the 4th ventricle develops, the alar plate (sensory nuclei) is pushed to the side, now sitting more lateral to the basal plate (motor nuclei).

Question 38

How are cranial nerve nuclei grouped?

Answer 38

Based on function

Question 39

Which nuclei are closer to the midline?

Answer 39

Motor nuclei (motor column)

Question 40

Which nuclei are positioned laterally?

Answer 40

Sensory nuclei (sensory column)

Question 41

How are the sensory and motor nuclei grouped within the brainstem?

Answer 41

Into 3 medial motor columns and 3 lateral sensory columns.

Question 42

What are the 3 motor columns (medial to lateral)?

Answer 42

General somatic motor Branchial motor General visceral

Question 43

What are the 3 sensory columns (medial to lateral)?

Answer 43

General and special visceral General somatic Special somatic

Question 44

Which nucleus is this?

Answer 44

Spinal trigeminal

Question 45

What is the tegmentum continuous with rostrally?

Answer 45

Certain nuclei in the thalamus

Question 46

What is the tegmentum continuous with caudally?

Answer 46

Intermediate grey of the spinal cord

Question 47

What is the function of the tegmentum rostrally (midbrain and upper pons)?

Answer 47

Mantains alert conscious state.

Question 48

What is the function of the tegmentum caudally (pons and medulla)?

Answer 48

Work together with cranial nerve nuclei and spinal cord to carry out a variety of important motor reflex and autonomic functions. Closer to spinal cord, therefore more spinal cord-like actions.

Question 49

What is the ascending reticular activating system?

Answer 49

Long projection systems from the rostral tegmentum.

Question 50

What 4 different systems does the ascending reticular activating system use?

Answer 50

Noradrenergic (locus cereleus) Dopaminergic (e.g. substantia nigra) Serotonergic (dorsal raphe nucleus) Cholinergic

Question 51

What functions does the caudal reticular formation serve crucial functions in?

Answer 51

Motor reflex and autonomic functions

Question 52

What does the ventrolateral medullary (VLM) reticular formation do?

Answer 52

Regulates the visceral functions of CNX (Vagus): G I responses (swallowing, vomiting) Respiratory activities Rhythm, coughing, hiccupping, sneezing Cardiovascular responses

Question 53

What is the lateral medullary pontine reticular formation important for?

Answer 53

Chewing

Question 54

What is the region of the reticular formation surrounding the facial nucleus important for?

Answer 54

Crying and smiling

Question 55

What are the 3 major pathways traversing the brainstem?

Answer 55

Ascending pathways: 1. Dorsal column-medial lemniscus system 2. Anterolateral system Descending pathways: 1. Corticospinal tract

Question 56

Which sensory modality is the dorsal column-medial lemniscus system for?

Answer 56

Fine touch-tactile, vibration

Question 57

Where does the dorsal column-medial lemniscus system decussate?

Answer 57

In the medulla, at the medial lemniscus

Question 58

Which sensory modality is the anterolateral system for?

Answer 58

Pain and temperature

Question 59

Where does the anterolateral system terminate?

Answer 59

In 3 different regions: thalamus, midbrain and reticular formation.

Question 60

What is the function of the corticospinal tract?

Answer 60

Motor

Question 61

Where does the corticospinal tract decussate?

Answer 61

At the pyramids

Question 62

What do the dorsal aspects of the brainstem contain?

Answer 62

Cranial nuclei and reticular formation

Question 63

What do the ventral (basis) aspects of the brainstem contain?

Answer 63

Structures associated with the descending motor tracts (corticospinal tracts). Midbrain: cerebral peduncles, substantia nigra, red nuclei Pons: CB nuclei, middle cerebellar peduncle Medulla: inferior olivary nuclei