Neuro-localization studio

Spinal cord lesion lab

TAP A SYNDROME
THEN THE TRACTS
Dorsal columnsCorticospinalSpinothalamicLesion
DORSAL / POSTERIORANTERIOR / VENTRAL
midline dorsalcolumnslat. cortico-spinallat. spino-thalamicanteriorcommissure
Tap any colored tract for its crossing rule.

1. Dorsal columns: cross high

Vibration, proprioception and fine touch ascend ipsilaterally in the cord, then decussate in the caudal medulla. A cord hemilesion → ipsilateral loss below.

“Same side in the spinal cord.”

2. Corticospinal: cross high

Most fibers cross at the pyramidal decussation (caudal medulla). A cord lesion → ipsilateral UMN weakness below; an anterior-horn hit adds LMN signs at that segment.

“Motor has already crossed.”

3. Spinothalamic: cross low

Pain and temperature enter, travel up/down about 1–2 segments in Lissauer tract, then cross through the anterior white commissure. A unilateral cord lesion → contralateral loss beginning 1–2 levels below.

“Pain crosses close to home.”
Classic trap: Central cord damages the crossing pain/temperature fibers first → a bilateral, suspended “cape-like” pattern (often cervical; think syringomyelia). Dorsal columns are usually spared early.