Draw a cross-section of the upper eyelid. Label all important structures and write short notes on each

The eyelids have a six-layered structure. From superficial to deep these layers are:

skin:

– thinnest on the body

– insertion of some of the fibres of levator palpebrae superioris causes the upper lid skin crease

subcutaneous tissue:

– there is no subcutaneous fat

– extracellular fluid or blood can accumulate in this layer

orbicularis oculi:

– innervated by the facial nerve

– palpebral fibres are responsible for reflex blinking

loose areolar tissue:

– the neurovascular bundle runs here

tarsal plate:

– 10 mm in height

– thickening of the orbital septum forming the fibrous framework of the eyelid

– 108each upper lid contains the 35 or so Meibomian glands. These modified sebaceous glands secrete the lipid outer layer of the tear film. Meibomian gland orifices are at the mucocutaneous junction lying behind the eyelashes

– levator palpebrae superioris inserts into the tarsal plate. It is innervated by the superior division of the oculomotor nerve and acts to elevate the upper lid

– Muller’s muscle also inserts into the tarsal plate: it originates from the posterior aspect of levator palpebrae superioris. Muller’s muscle is innervated by the sympathetic nervous system and elevates the upper lid by about 2 mm

palpebral conjunctiva:

– firmly adherent to the tarsal plate and in continuity with the forniceal conjunctiva.