Final answer:
The term canthal pertains to the angle where the eyelids meet at either the medial or lateral aspect of the eye.
Step-by-step explanation:
The term canthal (canth/al) denotes pertaining to the angle where the eyelids meet, either on the side closer to the nose (medial canthus) or on the side closer to the temple (lateral canthus) of the eye. The canthal area is an essential aspect of the eye's anatomy, as it plays a critical role in the proper drainage of tears through the lacrimal system and also contributes to the aesthetic appearance of the eyes.
The eye's structure is complex, with the palpebral conjunctiva membrane covering the inner surface of the eyelids and extending over the anterior surface of the eye. The medial canthus of the eye is where tears produced by the lacrimal gland flow over the conjunctiva through the lacrimal duct, washing away foreign particles and providing protection.