USMLE World Neuroanatomy Flashcards Preview

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Flashcards in USMLE World Neuroanatomy Deck (11):
1

Location of lesion and possible causes of a monocular scotoma

Partial lesion in the retina, optic disk, or optic nerve

Macular degeneration, optic neuritis

2

Location of lesion and possible causes of a right anopia

Right optic nerve

Retinal artery or central retinal vein occlusion

3

Location of lesion and possible causes of a bitemporal hemianopia

Optic chiasm

Pressure exerted by a pituitary tumor, craniophayngioma, aneurysm of ACA

4

Location of lesion and possible causes of a right nasal hemianopia

Right perichiasmal lesion

Calcification or aneurysm of the internal carotid artery impinging on uncrossed lateral retinal fibers

5

Location of lesion and possible causes of a left homonymous hemianopia

Right optic tract or optic radiation

Optica tract: occlusion of anterior choroidal artery

Optic radiation: occlusion of a MCA branch OR lesion involving posterior limb of internal capsule

6

Location of lesion and possible causes of a left homonymous superior quadrantanopia (pie in the sky)

Right temporal lobe (Meyer's loop)

Lesion or stroke involving temporal lobe
(Typically what artery?)

7

Location of lesion and possible causes of a left homonymous inferior quadrantanopia (pie on the floor)

Right parietal lobe (dorsal optic radiation)

Lesion or stroke involving parietal lobe
(Typically what artery?)

8

Location of lesion and possible causes of a left homonymous hemianopia with macular sparing

Right primary visual cortex (occipital lobe

Occlusion of PCA. Macula is spared due to collateral blood from the MCA.

9

Pupillary light reflex involves what structures?

Ipsilateral optic nerve --> bilateral pretectal nucleus --> bilateral Edinger-Westphal nuclei --> bilateral ciliary ganglion --> bilateral pupillary sphincter muscles (parasympathetic nervous system)

10

What is a relative afferent (Marcus Gunn) pupillary defect?

Lesion of afferent limb of pupillary light reflex;
Light in affected eye -> neither constricts;
Light in normal eye --> both constrict;
Light back to affected eye --> apparent dilation of both pupils because stimulus carried through that optic nerve is weaker; seen in MS

11

Symptoms of CN IX lesion:

Loss of gag reflex (afferent limb); loss of sensation in the upper pharynx, posterior tongue, tonsils, and middle ear cavity; and loss of taste in posterior tongue.