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The superior tarsus (tarsus superior; superior tarsal plate), the larger, is of a semilunar form, about 10 mm (0.4 in) in breadth at the center, and gradually narrowing toward its extremities. It is adjoined by the superior tarsal muscle. To the anterior surface of this plate the aponeurosis of the levator palpebrae superioris is attached.
Meibomian glands (also called tarsal glands, palpebral glands, and tarsoconjunctival glands) are sebaceous glands along the rims of the eyelid inside the tarsal plate. They produce meibum , an oily substance that prevents evaporation of the eye's tear film .
The muscle derives its name from Greek ταρσός 'flat surface', typically used for drying.. The term Müller's muscle is sometimes used as a synonym. [3] However, the same term is also used for the circular fibres of the ciliary muscle, [4] [5] and also for the orbitalis muscle that covers the inferior orbital fissure.
Eyelid edema is a condition in which the eyelids are swollen and tissues contain excess fluid. It may affect eye function when it increases the intraocular pressure. Eyelid edema is caused by allergy, trichiasis or infections. [4] The main symptoms are swollen red eyelids, pain, and itching. Chronic eyelid edema can lead to blepharochalasis.
The levator palpebrae superioris receives motor innervation from the superior division of the oculomotor nerve. [ 1 ] [ 2 ] [ 3 ] The smooth muscle that originates from its undersurface, called the superior tarsal muscle is innervated by postganglionic sympathetic axons from the superior cervical ganglion .
In the upper eyelid, the orbital septum blends with the tendon of the levator palpebrae superioris, and in the lower eyelid with the tarsal plate. [2]When the eyes are closed, the whole orbital opening is covered by the septum and tarsi.
The superior tarsal muscle elevates the upper eyelid. The levator palpebrae superioris, which is supplied by a branch of the oculomotor nerve, also elevates the upper eyelid. Eyelid elevation is therefore under both voluntary and involuntary control. Interruption of either pathway will result in eyelid droop .
Glands of Krause are located in the stroma of the conjunctival fornix, and the glands of Wolfring are located along the orbital border of the tarsal plate. [2] These glands are oval and display numerous acini. The acini are surrounded, sometimes incompletely, by a row of myoepithelial cells.