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YR2: Neuroscience and Mental Health > Organisation of the Brainstem and Cranial Nerves > Flashcards

Organisation of the Brainstem and Cranial Nerves Flashcards

1
Q

Where are the colliculi found and what are their functions?

A

Roof of the midbrain
Superior: coordination of eye + neck movement
Inferior: auditory reflexes – turning head in direction of loud noise

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2
Q

Describe the location of the pons relative to the ventricular system.

A

Pons is the floor of the 4th ventricle

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3
Q

Name the unpaired, midline structure on the posterior aspect of the brainstem.

A

Pineal gland

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4
Q

What is the role of the pineal gland?

A

Produces melatonin (involved in regulating circadian rhythms)

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5
Q

Which cranial nerve emerges from the back of the brainstem?

A

Trochlear nerve

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6
Q

What is the role of the Trochlear nerve? (CN IV)

A

Supplies superior oblique muscle: 1 of the extrinsic muscles of the eye

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7
Q

What structure defines the medulla in the dorsal aspect and what pathways are found within this structure?

A

Dorsal Columns.

Sensory pathways – touch + proprioception

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8
Q

What 3 significant structures can be seen superior to the pons when viewing the brainstem from an anteroinferior view?

A

Optic Chiasm
Pituitary Stalk (infundibulum)
Mammillary Bodies

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9
Q

What are the mammillary bodies?

A

The inferior part of the hypothalamus (part of the limbic system)

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10
Q

Which cranial nerve emerges in the midline just above the transverse fibres of the pons?

A

Oculomotor Nerve (CN III)

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11
Q

What are the cerebral peduncles? What is the significance of the word ‘peduncle’?

A

Descending motor tracts from the motor cortex.

Peduncle = a structure that has a functional + structural role – it holds the cerebrum onto the brainstem

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12
Q

Name the cranial nerve that emerges from the lateral aspect of the pons.

A

Trigeminal (CN V)

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13
Q

What is the role of the Trigeminal nerve? (CNV)

A

Touch + sensation throughout the head + neck
It has a small root next to the larger one as it emerges out of the transverse fibres = motor root providing motor innervation of the muscles of mastication

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14
Q

Which 3 nerves emerge at the pontomedullary junction (from medial to lateral)?

A

Medially: Abducens (CNVI)
Lateral: Facial (CNVII)
(more) Lateral: Vestibulocochlear (CNVIII)

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15
Q

Briefly state the role of CN VI, VII, VIII

A

Abducens: innervates lateral rectus, allows lateral eye movement
Facial: innervates muscles of facial expression + taste sensation for anterior 2/3 of tongue
Vestibulocochlear: involved in balance + hearing

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16
Q

Which 3 nerves emerge from the lateral medulla?

A

Glossopharyngeal (CNIX)
Vagus (CNX)
Accessory (CNXI)

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17
Q

Briefly state the role of CN IX, X, XI

A

Glossopharyngeal: sensory + motor innervation of the tongue + pharynx
Vagus: main parasympathetic output to the viscera
Accessory: supplies the trapezius + sternocleidomastoid

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18
Q

State the last cranial nerve – CN XII.

A

Hypoglossal: supplies musculature of the tongue

19
Q

The motor fibres coming down from the motor cortex come via the cerebral peduncles then disappear behind the transverse fibres of the pons. What structure do they re-emerge as, inferior to the transverse fibres?

A

Pyramids
If a problem occurs in the corticospinal tract it results in “pyramidal symptoms”
If problems in cerebellum/ other parts involved in motor control = “extrapyramidal symptoms”

20
Q

What percentage of motor fibres cross to the contralateral side of the body in the brainstem and where does this changing of sides take place?

A

90-95%

At the base of the medulla

21
Q

What are the 4 functional subtypes of the cranial nerves and what are their actions?

A

General Somatic Afferent: Sensation from skin + mucous membranes
General Visceral Afferent: Sensation from GIT, heart, vessels + lungs
General Somatic Efferent: Muscles for eye + tongue movements
General Visceral Efferent: Preganglionic parasympathetic

22
Q

What are the special subtypes of cranial nerves and what are their actions?

A

Special Somatic Afferent: Vision, hearing + equilibrium
Special Visceral Afferent: Smell + Taste
Special Visceral Efferent: Muscles involved in chewing, facial expression, swallowing, vocal sounds + turning head

23
Q

What structure separates the sensory nuclei from the motor nuclei in the spinal cord and brainstem?

A

Sulcus limitans

24
Q

What happens in the formation of the rhombencephalon and how does this affect the arrangement of the nuclei?

A

Alar plate opens up, a ventricle forms

This opening of the alar plate results in motor nuclei being medial in the brainstem + the sensory nuclei lateral

25
Q

Describe the arrangement of the different groups in columns within the brainstem.

A

Motor: Medial. Arranged in columns from medial to lateral in this order: GSE, SVE, GVE
Sensory: Lateral. Arranged in columns from medial to lateral in this order: GVA/SVA, GSA, SSA

26
Q

State the nuclei that are in the general somatic efferent group and describe their location within the brainstem.

A

Oculomotor + Trochlear = midbrain
Abducens = pons (though emerges at the ponto-medullary junction)
Hypoglossal = medulla

27
Q

State the nuclei that are in the special visceral efferent group and describe their location within the brainstem.

A

Trigeminal + Facial = pons
Ambiguus = medulla
Accessory = cervical spinal cord

28
Q

State the nuclei that are in the general visceral efferent group and describe their location within the brainstem.

A

Edinger Westphal = midbrain
Salivatory = ponto-medullary border (3 sets of salivatory nuclei)
Vagus = medulla

29
Q

State the nuclei that are in the special somatic AFFERENT group and describe their location within the brainstem.

A

Vestibulocochlear = pons + medulla

30
Q

State the nuclei that are in the general somatic AFFERENT groupand describe their location within the brainstem.

A

Trigeminal = in all 3 parts + in the cervical spinal cord

31
Q

State the nuclei that are in the general visceral AFFERENT and special visceral AFFERENT groups and describe their location within the brainstem.

A

Solitarius – mainly in the medulla (+ a little bit in pons)

32
Q

Describe the appearance of a cross-section of the midbrain. What are the key features seen?

A

‘Mickey mouse’ appearance
Ears= cerebral peduncles
Where the cerebral peduncles meet the rest of the midbrain = substantia nigra
Cerebral aqueduct in the middle (small diamond shape)
The 2 rounded protrusion on the opposite side of the cerebral peduncles = inferior colliculi

33
Q

What is the substantia nigra? Describe its clinical significance.

A

A group of dopaminergic neurons
Produce neuromelanin, (gives black colour of the substantia nigra)
PD is caused by loss of these dopaminergic neurons so patients with PD have a pale substantia nigra

34
Q

Describe the appearance of a cross-section of the pons. What are the key features seen?

A

The 4th ventricle will be seen at the dorsal aspect
Most distinctive feature= the transverse fibres
On either side you will see the middle cerebellar peduncles

35
Q

What is the difference between the peduncles seen in the midbrain and the ones seen in the pons?

A

Midbrain: cerebral peduncles
Pons: cerebellar peduncles

36
Q

Describe the appearance of a cross-section of the medulla. What are the key features seen?

A

Pyramids on the ventral aspect
Inferior olivary nucleus next to the pyramids
The 4th ventricle will still be visible

37
Q

What is the role of the inferior olivary nucleus?

A

Involved in fine tuning motor function

38
Q

Describe the appearance of a cross-section of the lower medulla. What are the key features seen?

A

It will be more round
Central canal in the middle
Dorsal columns on the dorsal side
Pyramidal decussation (crossing of 90% fibres)

39
Q

Name the 2 columns that make up the dorsal columns.

A

Gracilis: more medial – sensory info. from lower limb
Cuneatus: more lateral – sensory info. from upper limb

40
Q

What is lateral medullary syndrome? Describe and explain the symptoms.

A

Group of symptoms caused by thrombosis of vertebral artery or posterior inferior cerebellar arteries (PICA)
Causes:
Horner’s Syndrome (disturbing sympathetic tract)
Vertigo (disturbing the vestibular nucleus)
Ipsilateral loss of pain/thermal sensation on the face (disturbing spinothalamic tract)
Contralateral loss of pain/thermal sensation (trunk + limbs– disturbing spinothalamic tract)
Ipsilateral cerebellar ataxia (disturbing inferior cerebellar peduncle)

41
Q

What are the symptoms of Horner’s Syndrome?

A

Ptosis
Lack of sweating around the eye
Hoarseness
Difficulty Swallowing

42
Q

What is the brainstem?

A

Part of the CNS, exclusive of the cerebellum

Lies between the cerebrum + spinal cord

43
Q

What are the 3 major divisions of the brainstem?

A

Medulla oblongata
Pons
Midbrain

YR2: Neuroscience and Mental Health (20 decks)

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