Brain/spinal tracts, classic lesions and their deficits, and high-yield neuro pathology.
42 cards · basic cards · AI-written, checked twice. Edit anything.
- Where does the corticospinal tract originate?
- Motor cortex (Brodmann area 4), premotor cortex (area 6), and supplementary motor area
- What percentage of corticospinal tract fibers decussate at the pyramids of the medulla?
- Approximately 90 percent; the remaining 10 percent descend ipsilaterally in the ventral corticospinal tract
- What does a positive Babinski sign indicate?
- UMN lesion, usually involving the corticospinal tract
- At what level do spinothalamic tract fibers cross the midline after entering the spinal cord?
- 1-2 segments rostral to entry (they synapse in the dorsal horn and immediately cross)
- What sensory pattern occurs with a unilateral spinothalamic tract lesion in the spinal cord?
- Contralateral loss of pain and temperature sensation beginning 1-2 segments below the lesion
- In Brown-Sequard syndrome, what is the pattern of sensory loss?
- Ipsilateral loss of proprioception and vibration (dorsal columns) and contralateral loss of pain and temperature (spinothalamic tract)
- Where do dorsal column fibers decussate?
- In the medulla via internal arcuate fibers that cross at the medullary pyramids
- Which dorsal column tract carries lower extremity proprioception and vibration?
- Fasciculus gracilis (cuneatus carries upper extremity)
- Which dorsal column tract carries upper extremity proprioception and vibration?
- Fasciculus cuneatus (gracilis carries lower extremity)
- Weber syndrome results from a lesion in which part of the brainstem?
- Ventral midbrain, affecting CN III fascicles and the cerebral peduncle
- What are the clinical findings in Weber syndrome?
- Ipsilateral CN III palsy (ptosis, down-and-out eye, dilated pupil) with contralateral hemiparesis
- What artery occlusion causes Wallenberg syndrome (lateral medullary syndrome)?
- Posterior inferior cerebellar artery (PICA), resulting in lateral medullary infarction
- Claude syndrome involves a lesion of which midbrain structure?
- Dorsal midbrain (tegmentum), involving the red nucleus and CN III fascicles, characterized by ipsilateral CN III palsy with contralateral cerebellar signs (ataxia/tremor).
- Central cord syndrome is classically caused by what mechanism?
- Hyperextension injury (usually in elderly with cervical spondylosis), affecting the central gray matter
- What is the classic motor pattern in central cord syndrome?
- Disproportionate upper extremity weakness compared to lower extremities (cape-like or sacral-sparing distribution)