Lectures 8, 10: Brainstem and Cranial Nerves Flashcards

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1
Q

The trochlear nerve emerges __________ and wraps around the brainstem at what junction?

A

Ventrally; at the junction b/t the midbrain and pons

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2
Q

Motor nuclei are _______ and sensory nuclei are _______

A

Medial; lateral

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3
Q

Cortical innervation of cranial nerves is bilateral in all cases except (2)

A

Portion of VII and XII

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4
Q

What is the significance of bilateral cortical innervation of cranial nerves?

A

Unilateral cortical lesion would not impact nerve function

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5
Q

What is the sole CN that crosses the midline?

A

IV

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6
Q

Discuss the anatomy of the olfactory nerve

A

Short primary sensory nerves (cranial nerves) –> (cribiform plate) –> Olfactory bulb –> primary olfactory cortex

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7
Q

What is one way to damage olfactory nerve fibers? What process of the cell is damaged?

A

Anterior cranial fossa fractures; primary axons

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8
Q

How do you test for CSF rinorrhea?

A

Glucose or beta 2 transferrin

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9
Q

Anosmia

A

Loss of sense of smell

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10
Q

Parosmia

A

Perverted sense of smell

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11
Q

Olfactory hallucinations are often caused by…

A

Temporal lobe (parahippocampal) seizures

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12
Q

How do you test olfactory nerve function?

A

Coffee/vanilla, one side at a tie; note: don’t use an irritating smell

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13
Q

Temporary anosmia caused by colds affects what level of the olfactory system?

A

The receptors

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14
Q

What are four ways to damage the central processing structures of the olfactory system?

A

Contusion/laceration of olfactory bulb, aneurysm, olfactory groove meningioma, frontal lobe tumor

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15
Q

What are the 3 trigeminal sensory nuclei and what do each control?

A
  1. Spinal trigeminal: crude touch; 2. Pontine Trigeminal (chief): discriminative touch; 3. Mesencephalic: proprioception from muscles of mastication
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16
Q

Where is the trigeminal motor nucleus?

A

The pons

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17
Q

What are the 3 branches of the trigeminal nerve and where does each exit the skull?

A

V1: Opthalmic, superior orbital fissure; V2: Maxillary, foramen rotundum; V3: Mandibular, foramen ovale

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18
Q

Where are the cell bodies of the sensory fibers of the trigeminal nerve?

A

Trigeminal ganglion

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19
Q

What is unique about the cell bodies that control the jaw jerk reflex?

A

They are located in the mesencephalic nucleus, not the trigeminal ganglion

20
Q

What is one common condition associated with the trigeminal nerve? Describe this condition and a common cause

A

Trigeminal neuralgia; triggered by light touch/gustatory, rarely during sleep, pain-free intervals; common cause: vascular compression due to oligodendrocyte myelination

21
Q

The jaw deviates to the ________ side

A

Affected

22
Q

To test the 1st branch of the trigeminal ganglion, you can check which reflex?

A

Corneal

23
Q

What virus often effects the trigeminal nerve? What is one complication that must be evaluated for?

A

Herpes zoster; herpes opthalmicus (if it affets the opthalmic division)

24
Q

Why is the trigeminal nerve associated with an parasympathetic reflex?

A

Very close to superior salivatory nucleus –> sinus symptoms, watery eyes

25
Q

Where is the facial motor nucleus? The part of the nucleus supplying forehead muscles gets what type of innervation? What about lower facial muscles? What two muscles besides muscles of facial expression?

A

Pons; bilateral; contralateral; stapedius (dampens sound) and part of digastric

26
Q

Where are the cell bodies of the sensory fibers of the facial nerve? What nerve connects this ganglion to the brainstem nuclei?

A

Geniculate nucleus; nervous intermedius

27
Q

What does the GSA section of the facial nerve control? What nucleus?

A

Ear sensations (concha, behind ear, external auditory canal); spinal trigeminal

28
Q

What does the SVA section of the facial nerve control? What nucleus? What special nerve?

A

Taste from anterior 2/3 of tongue; solitary nucleus; chorda tympani

29
Q

What does the GVE section of the facial nerve control? What two nerves? What nucleus?

A

Lacrimal gland via V2 branches; Submandibular and sublingual via chorda tympani; superior salivatory nucleus

30
Q

Describe the basic anatomy of the facial nerve

A

Exits brainstem through cerebellopontine angle –> internal auditory meatus and facial canal –> stylomastoid foramen

31
Q

A lower motor neuron lesion causes facial palsy where? What are three common causes?

A

Palsy on same side as lesion on upper and lower face; Bell’s palsy, meningeal process (Guillain-Barre), or a stroke involving the VII nucleus

32
Q

An upper motor neuron lesion causes facial palsy where? What is a common cause?

A

Palsy on contralateral side as lesion on lower face only; stroke

33
Q

Describe the fives types of information carried by the Glossopharyngeal nerve

A

SVE: stylopharyngeus (swallowing); GVE: parotid gland; GSA: middle ear; SVA: taste from posterior 1/3 of tongue; GVA: touch from pharynx and posterior 1/3 of tongue, afferent limb of gag reflex, carotid body/sinus

34
Q

Describe the basic anatomy of the glossopharyngeal nerve. What are the associated nuclei?

A

Exits the brainstem ventrally from upper medulla –> jugular foramen; spinal trigeminal, nucleus ambiguus, solitary nucleus, caudal solitary nucleus, inferior salivatory nucleus

35
Q

Lesions of the glossopharyngeal nerve can cause (5)

A

Difficulty swallowing, taste impairment, impaired gag refelx, reduced saliva, syncope

36
Q

One condition unique to glossopharyngeal nerve

A

Glossopharyngeal neuralgia

37
Q

Describe the basic anatomy of the vagus nerve

A

Exist the brainstem from the medulla –> jugular foramen –> carotid sheath (inbetween internal carotid and internal jugular)

38
Q

The vagus nerve synapses on what four nuclei? Fiber type and functions?

A
  1. Dorsal nucleus of vagus nerve (GVE, parasympathetic output to viscera –> left colic flexure); 2. Nucleus ambiguus (SVE, brachial muscles of larynx/pharynx, upper esophagus, palate); 3. Solitary nucleus (SVA and GVA, epiglottal taste and sensation from mouth –> L colic flexure); 4. Trigeminal nucleus (GSA, dura, external ear and tympanic membrane)
39
Q

Six main functions of vagal nerve

A

Phonation, swallowing, palate elevation, taste, cutaneous sesnastion from ear, and visceral innervation (neck –> L colic flexure)

40
Q

What are some symptoms of vagal problems (4)

A

Loss of gag reflex, paralysis of soft palate (dyspnea, dysarthria, dysphagia), parasympathetic disturbances, lowering of palate and deviation of uvula

41
Q

What is unique about the uvula?

A

Deviates TOWARD normal side

42
Q

What are the two divisions of the spinal accessory nerve and how are they anatomically similar and different? What do they innervate?

A

Cranial division arises from the nucleus ambiguus –> jugular foramen –> intrinsic muscles of larynx but NOT cricothyroid; Spinal division arises from the ventral horn of C1 - C6 –> foramen magnum –> jugular foramen –> sternocleidomastoid and trapezius

43
Q

Three clinical correlations of the spinal accessory nerve

A
  1. Difficulty turning head to contralateral side; 2. Shoulder droop; 3. Larynx paralysis
44
Q

Describe the anatomy and basic function of the hypoglossal nerve

A

Mediates tongue movement; hypoglossal nucleus –> hypoglossal canal –> intrinsic and extrinsic tongue muscles

45
Q

If LMNs are involved, the how does the tongue deviate? IF UMNs?

A

Toward lesion; away from lesion

46
Q

What is Pseduobulbar palsy?

A

Bilateral corticobulbar tracts involved; inability to control facial movements, swallowing, spastic speech, emotional outbursts