The nictitating membrane is also known as which of the following?

The nictitating membrane is commonly referred to as the third eyelid. This membrane is a fold of tissue located in the inner corner of the eye in many animals, including cats and dogs. It serves several important functions, including protecting the eye from debris, aiding in tear distribution, and providing an additional layer of defense against injury. This membrane can be retracted or expanded, allowing it to cover the eye when necessary while still allowing for some vision.

The other possible names provided do not accurately represent the nictitating membrane. Terms like "first eyelid," "palpebral membrane," or "inner eyelid" do not correspond to the universally accepted terminology used in veterinary medicine to describe this anatomical structure. Recognizing the nictitating membrane as the third eyelid is essential for understanding its functions and relevance in veterinary care.