On a coronal MRI of the brain, the internal capsule is identified as a white matter band. The corticospinal fibres to the lower limb travel in which part of the internal capsule?

• A Anterior limb
• B Genu
• C Posterior limb — anterior two-thirds
• D Posterior limb — posterior one-third ✓

Explanation

Within the posterior limb of the internal capsule, the corticospinal fibres are arranged somatotopically: upper limb fibres are anterior and lower limb fibres are in the posterior one-third. The genu carries corticobulbar (corticonuclear) fibres. The anterior limb contains frontopontine and thalamocortical fibres. A small capsular lacunar infarct in the posterior limb can produce a pure motor hemiplegia with lower limb predominance if posteriorly placed.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.