During dissection of the open medulla, a prominent ridge is observed just medial to the inferior olivary complex, rostral to the pyramidal decussation. Which ascending tract forms this visible elevation on the ventral surface of the medulla?
- A Spinal lemniscus (spinothalamic tract)
- B Pyramidal tract
- C Medial lemniscus ✓
- D Medial longitudinal fasciculus
Correct answer: C. Medial lemniscus
Explanation
The medial lemniscus forms a distinct ridge on the ventral aspect of the medulla, lying medial to the pyramid and just rostral to the pyramidal decussation, after the internal arcuate fibres have crossed. Option B is the best distractor as the pyramid is also externally visible but lies lateral to this ridge. The spinal lemniscus lies more dorsolaterally and is not visible on the ventral surface. The MLF is a brainstem fibre tract not visible on the ventral medullary surface.
Reference: Gray's Anatomy, 42nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.