Neuroanatomy basics Practice Questions
20 free Neuroanatomy basics practice questions for the USMLE Step 1. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
A patient presents with loss of pain and temperature sensation on the right side of the body below the neck, along with left-sided facial pain loss. Which structure is most likely damaged?
- A Left lateral spinothalamic tract
- B Right lateral spinothalamic tract
- C Left medial lemniscus
- D Right corticospinal tract
Correct answer: Left lateral spinothalamic tract
Loss of contralateral body pain and ipsilateral facial pain suggests a lesion in the lateral medulla affecting the spinothalamic tract. This is characteristic of a lateral medullary (Wallenberg) syndrome.
A patient cannot abduct the eye. Damage to which cranial nerve is most likely responsible?
- A Oculomotor nerve
- B Trochlear nerve
- C Abducens nerve
- D Optic nerve
Correct answer: Abducens nerve
The abducens nerve (CN VI) innervates the lateral rectus muscle, which abducts the eye. Damage prevents lateral gaze.
A patient presents with spasticity, hyperreflexia, and an upgoing plantar reflex on the right side. Which tract is most likely damaged?
- A Right corticospinal tract above the decussation
- B Right corticospinal tract below the decussation
- C Left dorsal column
- D Left spinocerebellar tract
Correct answer: Right corticospinal tract below the decussation
Upper motor neuron signs on the right indicate a lesion in the corticospinal tract below the decussation in the spinal cord. This causes ipsilateral deficits.
Damage to the substantia nigra results in which clinical finding?
- A Intention tremor
- B Resting tremor
- C Hyperreflexia
- D Sensory ataxia
Correct answer: Resting tremor
Degeneration of dopaminergic neurons in the substantia nigra leads to Parkinson disease, characterized by resting tremor. It also causes rigidity and bradykinesia.
A patient with tabes dorsalis has positive Romberg sign. Which tract is primarily affected?
- A Spinothalamic tract
- B Dorsal column pathway
- C Corticospinal tract
- D Vestibulospinal tract
Correct answer: Dorsal column pathway
Tabes dorsalis affects the dorsal columns, impairing proprioception and vibration sense. Patients rely on visual input to maintain balance.
A patient has difficulty performing rapid alternating movements (dysdiadochokinesia). Which region is most likely affected?
- A Cerebellar hemisphere
- B Basal ganglia
- C Motor cortex
- D Medulla oblongata
Correct answer: Cerebellar hemisphere
The cerebellar hemispheres coordinate limb movement and rapid alternating motions. Damage causes ataxia and intention tremor.
Injury to the right optic tract causes which visual field defect?
- A Right homonymous hemianopia
- B Left homonymous hemianopia
- C Bitemporal hemianopia
- D Left superior quadrantanopia
Correct answer: Left homonymous hemianopia
The right optic tract carries fibers from the right retina and left visual fields. A lesion causes left homonymous hemianopia.
Damage to Broca's area leads to which type of deficit?
- A Fluent aphasia with impaired comprehension
- B Nonfluent aphasia with intact comprehension
- C Global aphasia
- D Impaired repetition only
Correct answer: Nonfluent aphasia with intact comprehension
Broca's area controls speech production. Lesions cause nonfluent aphasia with relatively preserved comprehension.
A lesion of the arcuate fasciculus produces which clinical syndrome?
- A Broca aphasia
- B Wernicke aphasia
- C Conduction aphasia
- D Global aphasia
Correct answer: Conduction aphasia
Damage to the arcuate fasciculus disrupts communication between Broca and Wernicke areas. Patients have poor repetition with preserved comprehension and fluent speech.
A patient presents with loss of facial pain and temperature sensation on the left and body pain and temperature loss on the right. Which structure is damaged?
- A Right lateral medulla
- B Left lateral medulla
- C Right pons
- D Left pons
Correct answer: Left lateral medulla
A left lateral medullary lesion (Wallenberg syndrome) affects ipsilateral facial pain loss and contralateral body pain loss. This pattern is classic for PICA infarction.
A lesion of the inferior cerebellar peduncle causes which deficit?
- A Ipsilateral limb ataxia
- B Contralateral limb ataxia
- C Bilateral tremors
- D Spastic paralysis
Correct answer: Ipsilateral limb ataxia
The inferior cerebellar peduncle carries proprioceptive input to the cerebellum. Lesions cause ipsilateral ataxia because cerebellar output influences ipsilateral body coordination.
Which neurotransmitter is primarily produced in the locus coeruleus?
- A Dopamine
- B GABA
- C Serotonin
- D Norepinephrine
Correct answer: Norepinephrine
The locus coeruleus is the major source of norepinephrine in the brain. It plays a key role in arousal and stress responses.
Bilateral damage to the hippocampus most severely affects which function?
- A Motor coordination
- B New memory formation
- C Postural balance
- D Visual processing
Correct answer: New memory formation
The hippocampus is essential for converting short-term memory to long-term memory. Damage results in profound anterograde amnesia.
A patient with a pituitary tumor develops bitemporal hemianopia. Which structure is compressed?
- A Optic nerve
- B Optic chiasm
- C Optic tract
- D Lateral geniculate nucleus
Correct answer: Optic chiasm
Compression of the optic chiasm disrupts crossing nasal fibers, causing loss of temporal visual fields. This produces bitemporal hemianopia.
Damage to the precentral gyrus results in which deficit?
- A Loss of somatosensation
- B Loss of motor function
- C Impaired visual processing
- D Impaired auditory comprehension
Correct answer: Loss of motor function
The precentral gyrus contains the primary motor cortex. Lesions cause contralateral motor weakness or paralysis.
A lesion of the facial colliculus results in facial paralysis and impaired lateral gaze. Which cranial nerves are involved?
- A CN VI and CN VII
- B CN IV and CN VII
- C CN III and CN IV
- D CN IX and CN X
Correct answer: CN VI and CN VII
The facial colliculus contains the abducens nucleus and fibers of the facial nerve. Lesions impair lateral gaze and facial movement.
A lesion of the ventral posterolateral (VPL) nucleus of the thalamus impairs which sensation?
- A Facial pain sensation
- B Body somatosensation
- C Auditory processing
- D Visual processing
Correct answer: Body somatosensation
The VPL nucleus receives sensory input from the body via spinothalamic and dorsal column pathways. Damage impairs contralateral somatosensation.
Atrophy of the caudate nucleus results in which condition?
- A Parkinson disease
- B Huntington disease
- C Multiple sclerosis
- D Amyotrophic lateral sclerosis
Correct answer: Huntington disease
Huntington disease is characterized by caudate atrophy due to CAG repeat expansion. It causes chorea, dementia, and behavioral changes.
A lesion affecting the dorsal columns below the medulla produces which deficit?
- A Contralateral vibration loss
- B Ipsilateral vibration loss
- C Contralateral pain loss
- D Ipsilateral pain loss
Correct answer: Ipsilateral vibration loss
Dorsal column fibers ascend ipsilaterally until they decussate in the medulla. Spinal cord lesions produce ipsilateral loss of vibration and proprioception.
Damage to the red nucleus impairs which motor pathway?
- A Rubrospinal tract
- B Corticospinal tract
- C Vestibulospinal tract
- D Reticulospinal tract
Correct answer: Rubrospinal tract
The red nucleus gives rise to the rubrospinal tract, involved in flexor control of the upper limbs. Damage reduces flexor facilitation.