Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Medical Studies 2A > 3.4 Cranial Nerves III-VII > Flashcards

3.4 Cranial Nerves III-VII Flashcards

You may prefer our related Brainscape-certified flashcards:
USMLE® Step 1 flashcards
1
Q

Which cranial nerves are responsible for extraocular eye movement?

A

CN III, IV, VI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When the superior and inferior oblique muscles contract together, they ___ the eye

A

Adduct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When the superior and inferior oblique muscles contract together, they ___ the eye

A

Abduct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Does the superior oblique depress or elevate the eye (in addition to intorsion and adduction)? Why?

A
  • It runs anterior to posterior
  • Therefore, it depresses the eye
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Does the inferior oblique depress or elevate the eye (in addition to extorsion and abduction)? Why?

A
  • It runs anterior to posterior
  • So it elevates the orbit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which of the superior/inferior rectus intort/extort the eye?

A

Superior: intorts
Inferior: extorts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the name of the muscle innervated by the occulomotor nerve that controls the eyelid?

A

Levator palpebrae superioris

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the two parasympathetic functions of the oculomotor nerve?

A
  • Pupil constriction
  • Lense accommodation (slackening) for near vision
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the two midbrain nuclei of the oculomotor nerve? What are their functions?

A
  • Oculomotor nucleus (somatic motor)
  • Edinger Westphal nucleus (parasympathetic)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Between which two arteries does the oculomotor nerve emerge from the ventral brain?

A

Superior cerebellar artery and posterior cerebral artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Does the oculomotor nerve control ipsilateral or contralateral eye movements?

A

Ipsilateral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Does the trochlear nerve supply ipsilateral or contralateral eye muscles?

A

Contralateral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the path of CN IV from the midbrain to its effector

A
  • Originates in nucleus of trochlear nerve
  • Crosses over, and emerges dorsally just beneath the inferior colliculi
  • Heads up to superior orbital fissure
  • Innervates superior oblique
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Does the abducens nerve control ipsi/contralateral eye muscles?

A

Ispilateral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the passage of the abducens nerve to its destination

A
  • Nucleus is in pons
  • Emerges at pontomedullary junction ventrally
  • Travels up to superior orbital fissure, passing over a bump in the occipital bone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Draw the H path gaze

A
  1. Abduct (LR)
  2. Look up (SR)
  3. Look down (IR)
  4. Adduct (MR)
  5. Look up (IO)
  6. Look down (SO)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the consensual light reflex

A
  • When light is shone in one eye, both pupils constrict
  • This is due to bilateral connections between pretectal nuclei and edinger westphal nuclei; CN III carries the “constrict” signal to both eyes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Consensual vs direct light reflex

A

Consensual: other eye
Direct: same eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are some signs of CN III palsy (outside of the light reflex)

A
  • Superior tarsal muscle is gone (drooping eyelid)
  • No more Para. innervation (pupil is dilated)
  • Only the SO and the LR remain (eye is depressed and abducted)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe the distribution of individual fibres within CN III; how does this affect the features of various pathologies?

A
  • Para. are on the outside, motor on the inside
  • In vascular diseases, blood can more easily get to Para, so this is less impaired
  • In compression (e.g. uncal herniation, PCA aneurysm), motor is more spared
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Explain the presentation of a CN IV palsy

A
  • SO depresses, abducts, intorts
  • In palsy, eye rotates upwards and outward
  • Double vision (different angles)
  • May adopt compensatory head tilt
22
Q

Explain the presentation of a CN VI palsy

A
  • LR abducts
  • Therefore eye is adducted
  • Patient fails to abduct
  • Double vision
23
Q

Describe the sensory function of the trigeminal nerve

A
  • Pain, temp, touch, and proprioception
  • Of the face, mouth, nasal cavity and cranial dura
24
Q

Describe the motor function of the trigeminal nerve (which muscles?)

A

Supplies muscles of mastication:
- Temporalis
- Medial/lateral pterygoid
- Masseter

25
Q

What are the three CN V sensory nuclei of the brainstem?

A
  • Mesencephalic (proprioception of temporomandibular joint)
  • Main sensory (discriminative touch & roprioception)
  • Spinal (pain, temp, crude touch)
26
Q

From which sensory nucleus of the trigeminal nerve does the trigeminal ganglion arise?

A

Main sensory nucleus

27
Q

Which sensory division of CN V is joined by the motor root?

A

Mandibular division.

28
Q

The neuronal cell bodies for pain/temp and touch/pressure of the face are located in the…

A

Trigeminal ganglion (everything except proprioception)

29
Q

What are the names of the three nuclei that the three branches of the sensory trigeminal nerve synapse at in the medulla?

A
  • Mesencephalic nucleus
  • Main sensory nucleus
  • Spinal trigeminal nucleus
30
Q

True or false: after reaching their brainstem nuclei, the secondary nerves in trigeminal pathways decussate to the other side of the brain

A

True

31
Q

What is the trigeminal lemniscus?

A

It’s a combination of the decussated fibres from the spinal nucleus and the main sensory nucleus of the trigeminal nerve; they bundle together, and head to the thalamus.

32
Q

What fibres are in the trigeminothalamic tract?

A

Those that have decussated from the trigeminal spinal nucleus

33
Q

Which nucleus in the thalamus do the sensory fibres of the periphery/CN V synapse on?

A

Periphery: ventral posteriolateral (VPL)

CN V: ventral posteriomedial (VPM)

34
Q

Which CN controls the sensory vs motor aspect of the jaw jerk?

A
  • Trick question
  • Both are CN V
35
Q

Are the trigeminal motor neurons ipsilateral or contralateral?

A

Ipsilateral

36
Q

What are the clinical signs of trigeminal nerve palsy?

A
  • Sensory loss
  • Jaw deviates towards side of lesion when mouth opened
37
Q

What are the classic clinical features of trigeminal neuralgia? What causes is it associated with?

A
  • Sudden, brief, excrutiating facial pain attacks in one/more branches
  • Thought to be caused by neurovascular compression -> demyelination & ion channel disregulation
38
Q

Which kinds of functions does the facial nerve have?

A
  • Motor
  • Special sense
  • Parasympathetic
39
Q

Which muscles does the facial nerve innervate?

A

Muscles of facial expression

40
Q

What is the special sensory function of CN VII?

A

Taste from anterior 2/3 of tongue

41
Q

What is the parasympathetic function of CN VII?

A

Tear glands and saliva glands (except parotid)

42
Q

At what level of the pons are the facial nerve nuclei?

A

Caudal

43
Q

Where does the facial nerve exit the brainstem?

A

Pontomedullary junction (remember: alongside 8)

44
Q

Where does the facial nerve exit the skull?

A

Internal acoustic meatus (facial canal)

45
Q

Where do the sensory/motor/para. components of the facial nerve exit the skull?

A

Motor: stylomastoid foramen
Para/sensory: facial canal

46
Q

Why doesn’t the facial nerve innervate the parotid gland?

A

Because by the time it exits the stylomastoid foramen, it has lost its parasympathetic and sensory components

47
Q

What are the five branches of the motor component of CN VII? What structures do they innervate?

A
  • Temporal (forehead)
  • Zygomatic (forceful eye closure)
  • Buccal (nostril, upper lip, blinking, raising mouth corner)
  • Mandibular (depressing lower lip)
  • Cervical (lower corner of mouth)
48
Q

Describe innervation of upper vs lower face (i.e., lateral vs bilateral)

A

Upper: bilateral
Lower: only contralateral

49
Q

LMN vs UMN facial lesion

A

UMN: Innervation of upper face is still intact due to other side (contralateral lower paralysis)

LMN: Innvervation of whole face is lost, since lesion is distal to mixing of fibres (ipsilateral, whole paralysis)

Remember the story of the nurse who thought she had Bell’s palsy

50
Q

Which nerves form the afferent/efferent arms of the corneal reflex?

A

Afferent: CN V
Efferent: CN VII

51
Q

What are some causes of lower facial nerve palsy?

A
  • Idiopathic (Bell’s)
  • Acute otitis media
  • Neoplasm
52
Q

CN VII lesion in facial canal vs in/outside stylomastoid foramen

A

Stylomastoid: muscle paralysis of lower face

Facial Canal: Also reduced lacrimation (para) and loss of taste (sensory)

Medical Studies 2A (110 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions