A 60-year-old diabetic man develops a right third nerve palsy limited to the inferior oblique, medial rectus and inferior rectus, with a normally functioning levator palpebrae superioris and normal pupil. Where is the lesion?

• A Inferior division of the oculomotor nerve ✓
• B Superior division of the oculomotor nerve
• C Edinger-Westphal nucleus
• D Cavernous segment of the oculomotor nerve

Explanation

Within the superior orbital fissure the oculomotor nerve divides into a superior division supplying the superior rectus and levator palpebrae superioris, and an inferior division supplying the medial rectus, inferior rectus and inferior oblique, with parasympathetic fibers to the ciliary ganglion traveling in the branch to inferior oblique. Selective involvement of the three inferior division muscles with sparing of lid function localizes to the inferior division.

Reference: Gray's Anatomy, 42nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.