Brainstem and Cranial Nerves

Question 1

Define Brainstem:

Answer 1

◦That part of the CNS, exclusive of the cerebellum, that lies between the cerebrum and the spinal cord

Question 2

What are the three major divisions of the Brainstem?

Answer 2

Midbrain

Pons

Medulla Oblongata

Question 3

Where is the Pons located in relation to other structures in the brain?

Answer 3

It is the floor of the 4th Ventricle

Question 4

What and Where is the Pineal Gland?

Answer 4

Located posteriorly in the midline above the Midbrain

It releases Melatonin and is important in regulating the Circadian Rhythm

Question 5

What does Colliculus mean and where are they located?

Answer 5

Low Lying Hills

4 - Superior and Inferior - Lying on the roof of the midbrain posteriorly

Question 6

What do the Colliculi do?

Answer 6

Superior Colliculus - important in the coordination of eye and head movements at the same time (think about watching tennis)

Inferior Colliculus - auditory reflexes - if there is a loud bang you tend to look in the direction of the bang immediately

Question 7

How many cranial nerves emerge from the back of the brainstem?

Which ones?

Answer 7

ONE

Trochlear Nerve (IV)

Question 8

What can be seen to define the Medulla in the dorsal aspect?

Answer 8

The Dorsal Columns

Question 9

What is located anteriorly to the brainstem?

(two structures)

Answer 9

Optic Chiasm

Infundibulum (Pituitary stalk)

Question 10

Identify the cranial nerves on this diagram:

9 are here (some are combined)

Answer 10

Question 11

What cranial nerves emerge from the Pons?

Answer 11

Five to Eight

Trigeminal (V)

Abducens (VI)

Facial (VII)

Vestibulocochlear (VIII)

Question 12

What Cranial nerves emerge from the lateral medulla?

Answer 12

Nine, Ten and Eleven

Glossopharyngeal (IX)

Vagus (X)

Accessory (XI)

Question 13

Where does the Hypoglossal nerve (XII) originate?

Answer 13

From the Medulla

More medially than IX, X & XI

Question 14

Show where fibres cross-over on this diagram:

What is this structure called?

Answer 14

At the join between the pyramids at the base of the medulla

Pyramidal Decussation

Question 15

What are the four functional subtypes of the Cranial nerves?

Answer 15

General Somatic Afferent (GSA)

General Visceral Afferent (GVA)

General Somatic Efferent (GSE)

General Visceral Efferent (GVE)

Question 16

What do GSA Cranial nerves transmit?

Answer 16

Sensation from skin and mucous membranes

Question 17

What do GVA Cranial nerves transmit?

Answer 17

Sensation from GI tract, heart, vessels and lungs

Question 18

What do GSE Cranial nerves transmit?

Answer 18

Motor signals for Eye muscle and tongue movements

Question 19

What do GVE Cranial nerves transmit?

Answer 19

Preganglionic Parasympathetic signals

Question 20

What are the three Special Functional Classifications of the Cranial nerves?

What do they do?

Answer 20

Special Somatic Afferent:

Vision, hearing and equilibrium (only the cranial nerves)

Special Visceral Afferent:

Smell (CN I) and Taste (comes from THREE cranial nerves that all go back to the nucleus solitarius)

Special Visceral Efferent:

Muscles involved in chewing, facial expression, swallowing, vocal sounds and turning the head

Question 21

Where are the different General functional subtypes of nerves located in the embryonic spinal cord?

Answer 21

Question 22

Where does information enter and leave the spinal cord?

Answer 22

Enters: Dorsal Root

Leaves: Ventral Root

Question 23

How are the four subtypes of cranial nerves arranged in the Embryonic Rhombencephalon?

How is this different from the Spinal cord?
Why is this?

Answer 23

Motor = Medial
Sensory = Lateral

(From medial to lateral)
GSE GVE GVA GSA

• Not Dorsal and Ventral because in the Brainstem the alar plate opens up and there is a ventricle there

Question 24

Have a guess at the Nuclei of Cranial Nerves in this diagram

Answer 24

Question 25

Wot is dis? What are the two main clues?

Answer 25

Midbrain - It looks like Mickey Mouse - You can see the Cerebral Aquaduct

Question 26

Label these areas on the Midbrain

Answer 26

Question 27

What is the black area in the Midbrain? Why is it black? What does it contain? What disease causes it to change colour?

Answer 27

Substantia Nigra Contains Dopaminergic Neurones Produces Neuromelanin in normal metabolism which is black Gets blacker and blacker as you age In Parkinson’s, you lose these neurones so it may turn pale

Question 28

Wot dis? Label it:

Answer 28

Pons

Question 29

What's this? Label it:

Answer 29

Medulla (Upper section)

Question 30

What is the Inferior Olivary Nucleus?

Answer 30

A structure connected to the cerebellum involved in fine-tuning motor movement

Question 31

Wot dis? Label it:

Answer 31

Lower Medulla

Question 32

What do the Dorsal Columns of the Medulla contain?

Answer 32

Touch and Proprioception information from the lower (Gracilis) and upper (Cuneatus) limb

Question 33

What is Lateral Medullary Syndrome caused by?

Answer 33

Thrombosis of the Vertebral artery or Posterior Inferior Cerebellar Artery (PICA)

Question 34

What is Horner's Syndrome and what does it cause?

Answer 34

Loss of Sympathetic innervation to the head and neck Ptosis (Drooping of upper eyelid) Lack of sweating around the eye Hoarseness Difficulty swallowing

Question 35

What may Lateral Medullary Syndrome result in? (five)

Answer 35

Vertigo Ipsilateral Cerebellar Ataxia (Broad-based Gait - shuffling) Ipsilateral loss of pain/thermal sense (face) Horner's Syndrome Contralateral loss of pain/thermal sense (Trunk and limbs)

Question 36

What causes the symptoms in Lateral Medullary Syndrome?

Answer 36

Vertigo: Disturbing the Vestibular Nucleus Ipsi Cerebellar Ataxia: Disturbing the Inferior Cerebellar Peduncle Horner's: Disturbing the sympathetic trunk Loss of Pain and Sensation from body: Spinothalamic tract

Question 37

What's the Mnemonic for remembering the type of fibres in the Cranial Nerves?

Answer 37

M - Motor S - Sensory B - Both **S**ome **S**ay **M**arry **M**oney **B**ut **M**y **B**rother **S**ays **B**ig **B**oobs **M**atter **M**ore

Question 38

What Cranial Nerves also have Parasympathetic Fibres?

Answer 38

III VII IX X Oculomotor, Facial, Glossopharyngeal, Vagus

Question 39

What are the functions of the Cranial Nerves I-III?

Answer 39

I: Olfaction II: Vision III: Movement of eyeball, Pupillary Constriction and accommodation (PSNS)

Question 40

What are the functions of the Cranial Nerves IV-VI?

Answer 40

IV: Movement of the eyeball V: General sensation, Opening/closing of Mouth, Tension of Tympanic membrane VI: Movement of eyeball

Question 41

What are the functions of the Cranial Nerves VII-IX?

Answer 41

VII: Taste, Facial movement, Tension of middle ear bones, Salvation + Lacrimation VIII: Vestibular sensation (Position of head) Hearing IX: General Sensation, Taste, Chemo/Baroreception, Swallowing, Salivation

Question 42

What are the functions of Cranial Nerve X?

Answer 42

**Sensory:** General Sensation, Chemo/Baroreception, Visceral sensation **Motor:** Speech, Swallowing **Parasympathetic:** Control of CVS, Respiratory and GI tract

Question 43

What are the functions of Cranial Nerves XI & XII?

Answer 43

XI: Movement of Head and Shoulder XII: Movement of Tongue