+
Related Flashcards
Cards In This Set
| Front | Back |
|
What are the 3 types of blinking?
|
1. Spontaneous2. Reflex3. Forced
|
|
Spontaneous blinking
|
Most common type of blinking. Maintains optics and comfort. Due to contraction of the palpebral portion or the orbicularis oculi NOT relaxation of the levator!
|
|
What is the spontaneous blink rate
|
15 blinks/minute
|
|
Reflex blinking: What causes it?
|
sensory stimuli. Auditory: detection of loud noises: CN8Touch/irritation: 5 senses 7 causes blinkDazzle: bright lights, CN2Menace: unexpected objects threatening the eye: CN2 causes blink response. The efferent loop of this reflex begins in the FRONTAL LOBE, blinking CAN INVOLVE cortical input!
|
|
What is Bell's phenomenon? When does it occur?
|
Voluntary closure of the lids produces an up and outward rotation of the globe for protective reasons: unlike reflex blinking, spontaneous blinking occurs in the absense of external stimulus: during a blink the globe is retracted approximately 1mm back into its socket
|
|
Forced Blinking:
|
VOLUNTARY closure that requires BOTH palpebral and orbital portions of the orbicularis: this is the closure that causes Bell's phenomenon
|
|
What portions of the orbicularis oculi are responsible for spontaneous and reflex blinking?
What portions of the orbicularis oculi are responsible for forced blinking? |
Spontaneous and reflex: palpebral portion
Forced: orbital AND palpebral |
|
What glands are involved in maintainance tear production? (5 of them)
|
MeibomianZeisMollKrause and Wolfring
|
|
Meibomian glands: what type of gland are they and what tear portion do they contribute to?
|
SebaceousContribute to lipid layer: BLINKING stimulates their secretionthese glands line the upper and lower eyelids
|
|
What method do the meibomian glands use for secreting their lipids?
|
holocrine
|
|
Zeis and Moll glands: what portion of the tears do they contribute to?
|
Lipid: these are sebaceous glands located in the tarsal plate. The are lesser contributers to the lipid layer
|
|
Accessory lacrimal glands: what are the two types and where are they located? What portion of the tears do they contribute?
|
Glands of Krause and WolfringKrause are in the fornix (crease)Wolfring are in the tarsal conjThese both contribute to the maintainance layer (aqueous) of the tears
|
|
What TYPE of glands are Krause and Wolfring?
|
Tubuloacinar exocrine glands
|
|
How are the tears distributed?
|
The UPPER lid blinks lateral to medially, wiping a thin film of tears over the corneal epithelium and bulbar conj.
|
|
What layer of the tear film does each blink spread evenly over the corneal epithelium?
|
The MUCOUS layer
|
