Unit 1: Eyelid/Eyebrows/Lacrimal System & Orbit

KMK

what are the layers of the eyelid?

1. skin layer

2. subcutaneous areolar layer

3. orbicularis layer

4. submuscular areolar layer

5. orbital septum

6. posterior muscular system

7. tarsal plate

8. palpebral conjunctiva

what makes the skin layer of the eyelid unique?

it is the thinnest tissue in the body and contains no fat

what does the subcutaneous areolar layer contain?

thin layer of loose connective tissue; contains the levator aponeurosis (facial tissue that connects the levator muscle to the upper lid)

list out the portions of the orbicularis layer and their function(s)

1. orbital: force closure of eyelids

2. palpebral: spontaneous and reflex blinking

what are the two specialized areas in the palpebral portion of the orbital portion, and its function?

muscle of Riolan (aka pars ciliaris): rotate lashes and keeps eyelid tight against eyelid margin and divides eye lashes anterior/posterior (Rio Tide DIVIDE)

muscle of Horner (pars lacrimalis): fibers that surround the canaliculi and help drain tears into the lacrimal sac

what is the most anterior portion of the muscle of Riolan?

gray line, groove located between the eyelash insertions and the meibo glands; serves as a surgical landmark during lid repair

paralysis of the orbicularsis will cause…

lower eyelid to droop away from the globe => ectropion

what does the submuscular areolar layer contain?

upper: levator aponeurosis and palpebral portion of the main lacrimal gland

what is the orbital septum and its function?