Neurology and neuroanatomy together make up roughly 8–10% of Step 1 and are among the most conceptually complex sections. The key is building spatial understanding of anatomy, then overlaying pathology on top of it.
Spinal Cord Tracts: The Non-Negotiable Foundation
You will see 3–5 spinal cord localization questions on Step 1. Every one of them is solvable with the same framework.
| Tract | Carries | Crosses where | Lesion effect |
|---|---|---|---|
| Dorsal columns (gracile + cuneate fasciculi) | Vibration, proprioception, fine touch (DCML pathway) | Decussates in medulla | Ipsilateral loss below lesion |
| Spinothalamic tract (anterolateral) | Pain and temperature | Crosses within 1–2 levels of entry (anterior white commissure) | Contralateral loss 1–2 levels below lesion |
| Corticospinal tract (lateral) | Motor (voluntary movement) | Decussates in medulla (pyramidal decussation) | Ipsilateral motor loss below lesion; UMN signs |
Classic spinal cord syndromes
Brown-Séquard (hemisection): Ipsilateral loss of vibration/proprioception + motor; contralateral loss of pain/temperature. Classic cause: penetrating trauma.
Syringomyelia: Bilateral loss of pain and temperature at the level of the lesion (spinothalamic fibers crossing in the anterior commissure are compressed). Arms affected more than legs ("cape distribution"). Preserved vibration and proprioception. Associated with Chiari malformation.
Anterior cord syndrome: Bilateral motor loss + bilateral pain/temperature loss below lesion. Vibration and proprioception spared (dorsal columns intact). Cause: anterior spinal artery occlusion.
Subacute combined degeneration (B12 deficiency): Posterior columns (vibration/proprioception) + lateral corticospinal tracts affected. Progressive, bilateral. Treat with B12 repletion.
Brain Lesion Localization
| Area | Function | Lesion effect |
|---|---|---|
| Frontal lobe (prefrontal) | Executive function, personality, Broca's area (inferior frontal gyrus, dominant) | Personality change, poor judgment; Broca's aphasia: non-fluent, comprehension intact |
| Parietal lobe (dominant) | Language (Wernicke's — superior temporal gyrus), reading, writing, calculation | Wernicke's aphasia: fluent speech, poor comprehension; Gerstmann's syndrome |
| Parietal lobe (non-dominant) | Spatial processing, attention to contralateral side | Hemispatial neglect (typically right-sided lesion → neglect of left side) |
| Temporal lobe | Memory (hippocampus), auditory processing | Amnesia, auditory hallucinations; bilateral: Kluver-Bucy syndrome |
| Occipital lobe | Visual processing | Contralateral homonymous hemianopia, visual agnosia |
| Cerebellum | Coordination, balance (ipsilateral) | Ipsilateral ataxia, intention tremor, dysdiadochokinesia, nystagmus |
| Basal ganglia | Modulate motor cortex via indirect/direct pathways | Parkinson's (↓dopamine), Huntington's (↓GABA/ACh striatum), hemiballismus (subthalamic nucleus lesion) |
Stroke Syndromes by Artery
| Artery | Territory | Classic presentation |
|---|---|---|
| MCA | Lateral cortex, basal ganglia, internal capsule | Contralateral face + arm > leg weakness; aphasia (dominant); neglect (non-dominant) |
| ACA | Medial frontal and parietal lobes | Contralateral leg > arm weakness; abulia, personality change |
| PCA | Occipital and inferior temporal lobes | Contralateral homonymous hemianopia with macular sparing; visual agnosia; alexia without agraphia (dominant) |
| PICA | Lateral medulla, cerebellum | Wallenberg (lateral medullary) syndrome: ipsilateral face pain/temp loss + contralateral body; Horner's; dysphagia; vertigo |
| Lacunar | Internal capsule, thalamus, pons | Pure motor or pure sensory stroke without cortical signs; small vessel disease (hypertension, diabetes) |
Neurodegenerative Diseases
| Disease | Pathology | Clinical features | Treatment |
|---|---|---|---|
| Alzheimer's | Amyloid plaques (Aβ) + neurofibrillary tangles (tau); ↓ACh; entorhinal cortex → hippocampus first | Memory loss first, then language, visuospatial; personality change late | Donepezil (AChEI); memantine (NMDA antagonist) for moderate-severe |
| Parkinson's | Loss of dopaminergic neurons in substantia nigra pars compacta; Lewy bodies (α-synuclein) | TRAP: Tremor (resting, "pill-rolling"), Rigidity (cogwheel), Akinesia/bradykinesia, Postural instability | Levodopa/carbidopa; dopamine agonists; MAO-B inhibitors (selegiline) |
| Huntington's | CAG trinucleotide repeat expansion on chromosome 4; loss of striatal GABA neurons | Chorea, dementia, psychiatric symptoms (depression, psychosis); anticipation | Tetrabenazine (depletes dopamine); supportive |
| ALS | UMN + LMN degeneration; TDP-43 aggregates; SOD1 mutation (familial) | Both UMN (spasticity, hyperreflexia) and LMN (fasciculations, atrophy) signs; no sensory, no eye movement, no sphincter involvement | Riluzole (glutamate antagonist); edaravone; supportive |
CNS Tumors: High-Yield
| Tumor | Origin/Location | Classic features |
|---|---|---|
| Glioblastoma multiforme (GBM) | Astrocytes; crosses corpus callosum ("butterfly glioma") | Adults 50–70; most malignant primary brain tumor; pseudopalisading necrosis |
| Meningioma | Arachnoid cells; attached to dura | Most common benign brain tumor in adults; women > men; psammoma bodies; good prognosis |
| Acoustic neuroma (schwannoma) | Schwann cells; CN VIII at CPA | Unilateral tinnitus, sensorineural hearing loss, vertigo; bilateral = NF2 |
| Medulloblastoma | Cerebellum (posterior fossa) | Most common malignant brain tumor in children; Homer-Wright rosettes; can seed via CSF |
| Craniopharyngioma | Rathke's pouch remnant; suprasellar | Children; bitemporal hemianopia; calcifications on imaging; "machine oil" cholesterol fluid |
Practice with adaptive questions
Progress Note has 6,000+ questions across Step 1, Step 2, NCLEX, and pre-med tracks — with test readiness scoring that updates every session.
Try free →