NBME Neuroscience 2

Question 1

A patient presents with a dilated, non-reactive pupil and ptosis of the right eye with the eye deviated down and out. Which cranial nerve is most likely compressed?

Accepted Answer

Cranial nerve III (oculomotor)

Answer

CN III palsy causes ipsilateral ptosis, dilated unreactive pupil (parasympathetic fibers run on outside), and 'down and out' eye deviation due to unopposed SO and LR action.

Question 2

A patient with a cerebellar lesion on the right side is most likely to show deficits on which side of the body?

Accepted Answer

Right side only

Answer

The cerebellum coordinates ipsilateral limb movements because cerebellar pathways cross twice (net ipsilateral), so right cerebellar lesions cause right-sided ataxia.

Question 3

Stimulation of the direct pathway of the basal ganglia results in which of the following?

Accepted Answer

Facilitation of movement via disinhibition of the thalamus

Answer

The direct pathway (striatum→GPi/SNr) inhibits GPi, disinhibiting the thalamus and facilitating cortical activation and movement.

Question 4

A patient is quadriplegic and anarthric but can move his eyes vertically and blink voluntarily. He is fully conscious. Which structure is most likely damaged?

Accepted Answer

Ventral pons

Answer

Locked-in syndrome results from ventral pontine lesions (often basilar artery occlusion) that destroy the corticospinal and corticobulbar tracts while sparing the ARAS and vertical gaze center in the midbrain.

Question 5

A patient presents with inability to close the right eye, drooping of the right corner of the mouth, and loss of taste from the anterior two-thirds of the right tongue. Where is the lesion?

Accepted Answer

Right facial nerve nucleus or nerve (LMN lesion)

Answer

LMN CN VII palsy causes complete ipsilateral facial paralysis (including forehead) plus taste loss from anterior 2/3 tongue via chorda tympani; UMN lesions spare the forehead.

NBME Practice Test

NBME Practice Test

NBME Neuroscience 2