Orbit and Cavernous Sinus - LO 2
2. Describe various components of the eyelid (palpebrae) and its associated structures.
The eyelids, layered from superficial-to-deep, include: skin, subcutaneous tissue, palpebral fibers of orbicularis oculi m. and associated connective tissues, a tarso-fascial layer, and palpebral conjunctiva (which rests upon the orbital conjunctiva of the eye). The superior eyelid includes the aponeurosis of the levator palpebrae superioris m attaching to the tarso-fascial layer. The edge of the eyelids host eyelashes and associated tarsal glands.
In other words, the tissues (superficial-to-deep) of the eyelids include:
Skin: continuous with the conjunctiva
Subcutaneous tissue: thin layer with little adipose tissue
Palpebral fibers of orbicularis oculi m.
Tarso-fascial layer: composed of tarsal plates, medial & lateral palpebral ligaments, tarsal glands, aponeurosis of levator palpebrae superioris m. (superior eyelid only), superior & inferior tarsal mm.
Palpebral conjunctiva: split into marginal, tarsal, and orbital parts
The conjunctiva is a delicate mucous membrane that lines the eyelids and covers the anterior aspect of the eyeball (excepting the cornea and pupil). The bulbar conjunctiva covers the eyeball, and the palpebral conjunctiva lines the eyelids. The conjunctival fornices (superior and inferior) are the reflections of conjunctiva from bulbar to palpebral conjunctiva, and the conjunctival sac is the potential space between bulbar and palpebral conjunctiva.
