Final answer:
Lesions at the CN 3 nucleus or at the level of the nerve both result in ipsilateral ptosis, meaning the eyelid droops on the same side as the lesion. The oculomotor nerve controls muscles involved in eyelid elevation, hence the direct effect.
Step-by-step explanation:
When discussing ptosis (drooping of the upper eyelid) in relation to cranial nerve III (oculomotor nerve) lesions, it's important to distinguish between a lesion at the nucleus level and a lesion at the nerve level. A lesion at the CN 3 nucleus will result in ipsilateral ptosis since the nucleus contains nerve fibers that will impact muscles of the same side of the lesion. Similarly, a lesion of the CN3 at the nerve outside the brainstem as it progresses toward the muscles it innervates also results in ipsilateral ptosis. The correct answer to your question, if you lesion the CN 3 nucleus or the nerve, what kind of ptosis will you get, is A) Ipsilateral Ptosis; Ipsilateral Ptosis.