A patient has a destructive lesion confined to the fasciculus gracilis on the right side at the T4 spinal level. Which sensory modality is lost, and on which side?

• A Pain and temperature on the left side below T4
• B Vibration and proprioception on the right side below T6 ✓
• C Vibration and proprioception on the right side above T6
• D Fine touch on the left side below T4

Explanation

In the dorsal columns, the fasciculus gracilis carries fibers from below T6 (lower trunk and legs) while the fasciculus cuneatus carries fibers from above T6 (upper trunk and arms). These first-order fibers ascend ipsilaterally and decussate only in the medulla, so a right-sided gracilis lesion at T4 abolishes vibration, proprioception and discriminative touch from the right leg. Pain and temperature travel in the anterolateral system, ruling out options A and D.

Reference: Gray's Anatomy for Students, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.