Which ocular muscle is responsible for elevating the eyelid?

The muscle primarily responsible for elevating the eyelid is the levator palpebrae. This muscle originates from the sphenoid bone and attaches to the upper eyelid, allowing it to lift the lid when it contracts. Its proper function is essential for maintaining an open eye and ensuring that vision is not obstructed by a drooping eyelid, a condition known as ptosis.

The other muscles mentioned in the question have different functions. The superior rectus primarily elevates the eyeball itself, not the eyelid, while the inferior rectus is responsible for depressing the eyeball. The medial rectus mainly controls the adduction of the eyeball by pulling it medially. Therefore, while these muscles contribute to various movements of the eye, none of them raise the eyelid; that function is specifically assigned to the levator palpebrae.