The tarsi are firm, dense plates of connective tissue that serve as the structural support of the eyelids (see Fig 9-7). The upper eyelid tarsal plates measure 10–12 mm vertically in the center of the eyelid; the maximum lower eyelid tarsal plate measurement is 4 mm. The tarsal plates have rigid attachments to the periosteum through the canthal tendons medially and laterally. The tarsal plates may become horizontally displaced with age as a result of stretching of the medial and lateral supporting tendons. Both tarsal plates are usually 1 mm thick and taper at the medial and lateral ends as they approach the canthal tendons. Located within the tarsus, the meibomian glands are holocrine sebaceous glands.