The attached or orbital margins are connected to the circumference of the orbit by the
orbital septum. The lateral angles are attached to the
zygomatic bone by the
lateral palpebral raphe. The medial angles of the two plates end at the
lacrimal lake, and are attached to the frontal process of the
maxilla by the
medial palpebral ligament). The
sulcus subtarsalis is a groove in the inner surface of each eyelid. Along the inner margin of the tarsus are modified sebaceous glands known as tarsal glands (or
meibomian glands), aligned vertically within the tarsi: 30 to 40 glands in the upper lid, and 20 to 30 in the lower lid, which secrete a lipid-rich product which helps keep the lacrimal secretions or tears from evaporating too quickly, thus keeping the eye moist. ==Additional images==