Bulbar Conjunctiva

We just learned about the Lacrimal Lake.

Another part of the eye is the Bulbar Conjunctiva.

This is a very thin layer of skin on top of the white sclera that helps bring tears to the eye, and also has blood vessels coming into the eye.


(from: wikipedia - conjunctiva)


Kid Facts - Blast from the past: Palatine Raphe

Lacrimal Lake

We just learned about the Canthus.

Another part of the eyes is the Lacrimal Lake.

This is in the inside corner of the eyes, where the tears pool up before they spill over onto the cheeks.


(from: wikipedia - lacrimal lake)


Kid Facts - Blast from the past: Incisive Papilla

Canthus

We just learned about the Meibomian Gland that helps keep your eyes wet.

Another part of the eye is the Canthus, or canthi for both of them.

This is the inner and outer corners of your eyes, where your upper and lower eyelids meet.

Remember the eyelids are called the palpebra, and another name for the canthus is the palpebral commissure.
The inner canthus is the "medial" palpebral commisure, and the outer canthus is the "lateral".


(from: wikipedia - canthus)


Kid Facts - Blast from the past: Palatal Rugae

Meibomian Gland

We just learned about the Epicanthic Fold.

Another part of the eye is the Meibomian Gland.

Just inside the top and bottom eyelids are some small glands that help keep your eyes wet.
They let out a little bit of oily liquid called meibum that helps spread around the water tears that come out, help keep the tears from spilling over onto your face, and help keep the water from just evaporating.

If someone is having problems with their meibomian glands they can get really dry eyes.
The word "meibomian" was named after the person who discovered the glands, Heinrich Meibom.

(from: wikipedia - meibomian gland)


Kid Facts - Blast from the past: Soft Palate

Epicanthic Fold

We just learned about the Eyelids.

Another part of the eye is the Epicanthic Fold.

The skin above the eyelid for some people is folded over and lays over the top of the eyelid.

This happens more for some people depending on where they come from.
Asian people from countries like China or Japan usually have a bigger epicanthic fold than people form North America or Europe.


(from: wikipedia - epicanthic fold)


Kid Facts - Blast from the past: Hard Palate

Eyelids

We just learned about the Nasolacrimal Duct.

Another part of the eye is the Eyelid, also called the palpebra, or palpabrea for both eyelids.

The upper eyelid is called the palpebra superior, and the lower is the inferior.

The job of the eyelids is to help protect the eye from wind, dirt or liquids, to help spread tears around the eye, and to close so that we can sleep at night.

Some people put makeup on their eyelids to color them, and some people even have plastic surgery on their eyelids to make them look higher or lower.


(from: wikipedia - eyelid)


Kid Facts - Blast from the past: Sublingual Caruncle

Nasolacrimal Duct

We just learned about the Lacrimal Sac.

Another part of how the eyes work is the Nasolacrimal Duct.

Remember tears in the eye go into the lacrimal punctum, through the lacrimal duct and then to the lacrimal sac.
After that they drain out into the nasal cavity through the nasolacrimal duct.

If you cry too much and there are too many tears, the nasal cavity will overflow, giving you a runny nose.
This is why sometimes if you cry a lot it makes your nose run.


(from: wikipedia - nasolacrimal duct)


Kid Facts - Blast from the past: Fimbriated Fold

Lacrimal Sac

We just learned about the Lacrimal Ducts which take the tears from the lacrimal punctum that drain from the eye.

The tears next go into the Lacrimal Sac.

This is a small place like a balloon that fills up with tears from the eye, before they are drained out.


(from: wikipedia - lacrimal sac)


Kid Facts - Blast from the past: Frenulum

Lacrimal Ducts

We just learned about the Lacrimal Punctum.

Another part of the eye is the Lacrimal Ducts, also called the lacrimal canals or lacrimal canaliculi.

When the water in your eyes from tears goes into the lacrimal punctum hole in your eyelid, it goes into the lacrimal ducts.
These are like little tubes that bring the water away from your eyeball.


(from: wikipedia - lacrimal canaliculi)


Kid Facts - Blast from the past: Foramen Cecum

Lacrimal Punctum

We just learned about the Lacrimal Gland.

Another part of the eye is the Lacrimal Punctum.

When tears come out of the lacrimal gland, they help keep the eye nice and wet.
If the tears do not run down your face, they will actually drain out through a hole in your lower eyelid called the lacrimal punctum.


(from: wikipedia - lacrimal punctum)


Kid Facts - Blast from the past: Sulcus Terminus

Lacrimal Gland

We just learned about the Depth Perception.

Another part of the eye is the Lacrimal Gland, also called the caruncula lacrimalis.

The word lacrimal comes from the latin word for tears like when you cry.
This gland is up above your eye, right behind the bone where your eyebrow is.

When you cry, this gland makes the tears that flow into your eyeball and make it all wet.


(from: wikipedia - lacrimal gland)


Kid Facts - Blast from the past: Median Sulcus

Depth Perception

We just learned about Rapid Eye Movement.

Another part of how eyes work is Depth Perception.

Because humans have two eyes that are set apart from each other, they can look at the world and tell if something is close and if something is far away.

With just one eye it is very hard to tell that, but because two eyes are looking at something from different angles, the human brain can use those two different pictures and figure out if something is close or far.


(from: wikipedia - depth perception)


(from: wikipedia - binocular vision)


Kid Facts - Blast from the past: Foliate Papillae

Rapid Eye Movement

We just learned about eye movement of Smooth Pursuit.

Another part of eye movement is Rapid Eye Movement also called REM.

Sometimes when a person is sleeping, their eyes will move around quickly in a bunch of different directions over and over again for a while.
The quick or rapid eye movement also happens at the same time as a lot of activity in the brain even while you are asleep.
Some scientists think that REM is what happens when you are having very active dreams.


(from: wikipedia - rapid eye movement sleep)


Kid Facts - Blast from the past: Foliate Papillae

Smooth Pursuit

We just learned about the Saccade quick jumpy eye movements.

Another type of eye movement is called Smooth Pursuit.

This is where your eye can follow something that is moving along without losing sight of it.
So if someone throws a ball up in the air, your eyes can focus on the ball and watch it the whole time as it goes up and down.

Or if someone hits a baseball, your eyes can watch it go through the air and you can run to catch it.


(from: wikipedia - smooth pursuit)


Kid Facts - Blast from the past: Fungiform Papillae

Saccade

We just learned about Peripheral Vision.

Another part of the eye is the Saccade.

When your eyes move, sometimes they move fast and sometimes they move slow.
If you quickly switch from looking at one spot to looking at another spot, that is called a saccade.

So if you are holding your open hand out, you can stare at your thumb and then quickly switch to staring at your pinky.
You don't need to slowly move your eyes along across the middle of your hand until you stop at your pinky, you just zip right over and look at it, and you can switch back and forth easily.

The word saccade is French for jerk, like a jerking movement as your eyes move around.


(from: wikipedia - saccade)


Kid Facts - Blast from the past: Filiform Papillae

Peripheral Vision

We just learned about the Field of View.

Another part of the eye is Peripheral Vision.

When you are looking straight ahead at something, you can still see things a little bit that are on the left and right sides of your head.

The word "peripheral" means on the outside or on the edge of something.
So peripheral vision is looking at things that are on the outside edge of what you are seeing.


(from: wikipedia - peripheral vision)


Kid Facts - Blast from the past: Taste Buds

Field of View

We just learned about the Central Retinal Vein.

Another part of the eyes is the Field of View.

When we are looking forward with our eyes, we see the things in front of us, but not behind us.
We also can only see part of what is up, down, left or right without moving our head to see it all.

Some of this is because parts of our head that get in the way like cheekbones or eyebrows.
Part of it is because our eyeballs are pointed forward.
Some animals like a rabbit or a deer have eyes on the sides of their heads, so they can see almost all the way in front and in back of their bodies.

The whole space of things that you can see with your eyes without moving them is called your Field of View, or FoV.



(from: wikipedia - peripheral vision)


Kid Facts - Blast from the past: Lingual Papillae

Central Retinal Vein

We just learned about the Central Retinal Artery.

Another part of the eye is the Central Retinal Vein.

The artery brings blood to the eye, and this vein in the back of the eye then takes that deoxygenated used up blood and brings it back to the heart.

(from: wikipedia - central retinal vein)


Kid Facts - Blast from the past: Specialized Mucosa

Central Retinal Artery

We just learned about the Optic Disc.

Another part of the eye is the Central Retinal Artery.

This is in the back of the eye at the retina, where the fresh oxygenated blood is brought to the eye for it to use.

(from: wikipedia - central retinal artery)


Kid Facts - Blast from the past: Lining Mucosa

Optic Disc

We just learned about the Opthalmic Artery.

Another part of the eye is the Optic Disc.

At the back of the eye there is a place where all the nerves come together and go out to the brain.
Because this spot has nerves, there are no rods or cones there, so it is like a blind spot in your sight.

There are some fun eye tests that you can do to actually show that you have a blind spot where things disappear from your sight!


(from: wikipedia - optic disc)


Kid Facts - Blast from the past: Masticatory Mucosa