Canthus (pl. canthi, palpebral commissures) is either corner of the eye where the upper and lower eyelids meet. More specifically, the inner and outer canthi are, respectively, the medial and lateral ends/angles of the palpebral fissure.

Is medial canthus upper or lower?

Medial canthus: the medial confluence of upper and lower eyelid margins. Lacrimal sac: collects tears coming from the canaliculi.

Where is the corner of your eye?

The nasolacrimal duct is known to you and me as the tear duct. It's the area found in the corner of your eyes, closest to the nose.