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MHD2 Block 2 - Neuro > Brainstem & Cranial Nerves + Disorders > Flashcards

Brainstem & Cranial Nerves + Disorders Flashcards

1
Q

What are the major divisions of the brainstem?

A

Midbrain, pons and medulla oblongata

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2
Q

What structures make up to corpora quadrigemini and how do their functions differ?

A

The superior and inferior colliculi make
SLO: superior colliculus uses the lateral geniculate to transmit optic information
AIM: auditory information is transmitted from the inferior colliculus via the medial geniculate

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3
Q

What cranial nerves exit the brainstem at the junction between the pons and medulla?

A

CN VI, VII and VIII

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4
Q

Describe the path of CN IV exiting the brainstem

A

Decussates immediately within the brainstem and exits laterally below the inferior colliculi on the posterior brainstem

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5
Q

What are the deep cerebellar nuclei (medial to lateral)

A

Fastigial, Globose, Emboliform, Dentate

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6
Q

What 2 ascending tracts are adjacent to one another in the pons and midbrain?

A

The medial lemniscus (dorsal column pathway) and spinothalamic tract are adjacent to one another in the pons and midbrain

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7
Q

Pair the Raphe, SN, locus ceruleus and nucleus of meynert with their neurotransmitters

A

Raphe: serotonin
Substantia nigra: dopamine
Locus ceruleus: noradrenalin
Meynert: Acetylcholine

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8
Q

What is lateral medullary syndrome?

A

The Lateral medulla is injured by occlusion of PICA
Patients present with ipsilateral facial sensory deficits (spinal trigeminal tract) and contralateral trunk/extremity sensory deficits (spinothalamic tract)

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9
Q

What is the difference between general somatic and general visceral nerves?

A

GS are to muscles, skin and body wall. Afferents transmit pain, temperature and proprioception. Efferents are common skeletal muscle motor neurons.

GV are to gut and autonomic. Afferents transmit pain from gut/viscera. Efferents are parasympathetic to gut, glands, blood vessels.

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10
Q

What is the difference between special somatic and special visceral nerves?

A

SS are sensory neurons from eyes and ears

SV are sensory from tongue and nose (Afferent) and motor to the branchial muscles (Efferent)

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11
Q

Where do the CN exit the brainstem (broadly)?

A

III and IV exit the midbrain
V, VI, VII, and VIII exit the pons
IX, X, XI, and XII exit the medulla

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12
Q

What are the components of CN I and what is innervated?

A

SVA innervation from the olfactory nasal mucosa (smell)

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13
Q

Describe the path of CN I

A

Pierces the cribiform plate of the ethmoid bone and forms the olfactory bulb. The olfactory tract projects to the olfactory cortex in the temporal lobe without relaying in the thalamus.

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14
Q

What are the components of CN II and what is innervated

A

SSA innervation to the retina (vision)

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15
Q

Describe the path of CN II

A

The optic nerves communicate with the lateral geniculate (thalamus) and superior colliculus. Optic radiations from the thalamus end up in the visual cortex (BA 17, 18)

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16
Q

What are the components of CN III and what is innervated?

A

GSE innervation to eye muscles (SR, MR, IR, IO)

GVE innervation to sphincter pupillae and cilliary muscles

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17
Q

Describe the path of CN III

A

Fibers originate from frontal eye fields (not motor cortex). Nuclei are just anterior to cerebral aqueduct of midbrain. Oculomotor nucleus (GSE) and Edinger-Westphal nucleus (GVE) project through the superior orbital fissure to reach the eye

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18
Q

What are the components of CN IV and what is innervated?

A

GSE innervation to the superior oblique muscle

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19
Q

Describe the path of CN IV

A

Trochlear nuclei are anterior to periaqueductal gray matter and inferior to the oculomotor nuclei. They send out curving projections around the PAG that cross and exit on the dorsal side of the midbrain before projecting forward through the superior orbital fissure to the eye ball.

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20
Q

What are the components of CN V and what is innervated?

A

GSA: pain and temp from upper face (V1), middle face (V2) and lower face (V3).
SVE: motor to muscles of mastication

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21
Q

Describe the path of CN V

A

3 nuclei (mesencephalic, main sensory, and spinal) project to the trigeminal ganglion which branches into 3 division (V1: opthalmic, V2: maxillary, V3: mandibular). V1 passes through the superior orbital fissure, V2 passes through the foramen rotundum, and V3 passes through the foramen ovale.

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22
Q

What is the function of the spinal nucleus/ spinal tract of V?

A

Pain, temperature, touch from face and mucous membranes (GSA). The spinal tract descends into the cervical spinal cord before innervating the spinal nucleus, which projects up to the VPM of the thalamus.

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23
Q

What is the function of the principle sensory nucleus of V?

A

Tactile and proprioceptive sensation (GSA)

Projects up to the VPM of the thalmus

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24
Q

What is the function of the mesencephalic nucleus of V?

A

Jaw jerk reflex

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25
What spinal nucleus is analagous to the principal nucleus of V? What about the spinal trigeminal nucleus?
Principal: like cuneatus | Spinal trigeminal: like nucleus proprius and STT
26
What are the components of CN VI and what is innervated?
GSE innervation to the lateral rectus
27
Describe the path of CN VI
Abducent nucleus is found just anterior to the 4th ventricle in the pons. Fibers project anteriorly and exit in the groove between the pons and the pyramid. Exits the skull through the superior orbital fissure to reach the LR muscle in the orbit.
28
What are the components of CN VII and what is innervated?
GVA: deep sensation from soft palate SVA: taste buds from anterior 2/3 of tongue GSA: sensation from ear pinna GVE: motor to submandibular, sublingual and lacrimal glands SVE: Motor to muscles of facial expression
29
Describe the path of CN VII
The facial nucleus (SVE) is in the pons, and projects neurons around the abducent nucleus. The superior salivatory nucleus (GVE) and nucleus of the solitary tract (SVA, GVA) also project fibers out of the pons as CN VII
30
What are the five branches of the SVE component of the facial nerve?
Temporal, Zygomatic, Buccal, Mandibular, Cervical
31
What is Bell's palsy?
Unilateral facial weakness caused by lesion of CN VII.
32
What is unique about the motor innervation of the upper half of the face compared to the lower half?
The upper half receives innervation from both sides of the brain, so a stroke or UMN lesion would cause unilateral lower face weakness without affecting the top half of the face
33
What are the components of CN VIII and what is innervated?
SSA innervation from organ of Corti (hearing) and semicircular canals (vestibular, balance)
34
Describe the path of CN VIII
The spiral ganglion of the cochlea projects to the cochlear nuclei in the medulla. CN VIII projects up to the inferior colliculus of the midbrain, and the medial geniculate of the thalamus (AIM)
35
What are the components of CN IX and what is innervated?
``` GVA: deep sensation from posterior tongue SVA: taste buds posterior 1/3 tongue GSA: sensation from ear pinna GVE: parotid salivary gland SVE: stylopharyngeaus muscle ```
36
Describe the path of CN IX
Nuclei in the midbrain project out through the dorsolateral medulla and through the jugular foramen with CN X and XI. Nuclei include nucleus of solitary tract, nucleus ambiguus, inferior salivatory nucleus and spinal nucleus of V
37
What are the components of CN X and what is innervated?
GVA: visceral sense from pharynx, esophagus, trachea SVA: taste buds from epiglottis and glottis GSA: sensory from ear pinna, tympanic membrane GVE: thoracic and abdominal viscera SVE: muscles of pharynx and larynx
38
Describe the path of CN X
Dorsal motor nucleus, solitary nucleus and nucleus ambiguus project out of medulla through the jugular foramen.
39
What are the components of CN XI and what is innervated?
SVE innervation to sternocleidomastoid and trapezius muscle
40
Describe the path of CN XI
Motor cortex projects down through foramen magnum and synapses on spinal accessory nucleus. CN XI fibers go back up through foramen magnum and then out the jugular foramen to reach its target muscles.
41
What are the components of CN XII and what is innervated?
GSE innervation to intrinsic and extrinsic muscles of the tongue
42
Describe the path of CN XII
Motor cortex projects to hypoglossal nucleus of the medulla, which projects anteriorly and exits midbrain between the pyramids and olives. Exits skull through the hypoglossal canal to reach target muscles.
43
What nerves make up the jaw-jerk reflex? lacrimation reflex? corneal blink reflex?
Jaw jerk: 5 to 5 Lacrimation: 5 to 7 Corneal blink: 5 to 7
44
Describe the result and most common etiology of a CN I lesion
Lesion of CN I results in anosmia and most often is the result of head trauma which shears nerve branches passing through the cribiform plate
45
What is the result of lesions of the extraocular muscles?
Diplopia (either binocular or monocular)
46
What is the difference between binocular and monocular dipolopia?
Binocular: single image vision when either eye is closed Monocular: double images when one eye is covered
47
Physical exam findings of a patient with complete lesion of CN III
Ptosis Large pupil unreactive to light Outward deviation
48
What is the presentation of a patient with a CN IV lesion?
Trochlear nerve | Superior oblique weakness causes adducted eye that does not fully depress
49
What is the presentation of a patient with a CN VI lesion
Abducens nerve | Lateral gaze, eye does not abduct
50
How do you differentiate a optic nerve lesion from an oculomotor nerve lesion with the pupillary light reflex?
In a CN II lesion, shining light into the affected eye will not cause either pupil to constrict, but light to the normal eye will elicit bilateral pupillary restriction. In a CN III lesion, shining light into the affected eye will cause contralateral contraction, but the affected eye remains dilated. Shining light into the unaffected eye will not contract the affected eye either.
51
Describe the near reflex
Lens accommodates, pupils constrict and eyes converge
52
What unique eye finding is seen in neurosyphilis and pineal tumors?
Dissociation of the light and near reflex Pupils constrict with near reflex, but not to light Neurosyphilis: Argyll Robertson pupil Pineal tumor: Parinaud's syndrome
53
What is Horner's syndrome?
Lesion of the cervical sympathetic nerves leading to miosis, anhidrosis and milt ptosis
54
Define nystagmus
Repetitive, oscillatory, jerky eye movements
55
What is internuclear opthalmoplegia?
Loss of coordination of lateral gaze. Partial paralysis of eye movements due to lesion between CN VI, Abducens nucleus, MLF and CN III Often seen in MS patients
56
What is trigeminal neuralgia?
Short circuiting nerve conduction causing extremely painful sensations in V2/V3 area of face.
57
Which side is affected by lesions of CN IX or X?
Ipsilateral signs and symptoms: decreased gag reflex, droopy palatal arch, hoarseness *Uvula deviated away from affected side
58
Which side is affected by lesions of CN XII?
"Lick your wounds" | Tongue points toward affected side do to unopposed protrusion of normal half of tongue
59
Describe crossed brain stem syndromes
Lesions in the brainstem can cause ipsilateral CN deficits with contralateral UMN limb weakness (CST decussates below brainstem)
60
Describe medial midbrain syndrome
AKA: Weber syndrome | PCA occlusion causes ipsilateral CN III lesion, contralateral hemiplegia

MHD2 Block 2 - Neuro (26 decks)

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