The eye and ear group of the model has 43 parts: 20 in the 2 eyeballs, 22 in the eyelids and tear system, and the outer ears. Each sclera, the white coat of the eye, is 2.6 cm across. The view also shows 37 nerves of the eye socket, among them both optic nerves.
The eye and ear of the model in 4 groups
| Group | Parts | What it holds |
|---|---|---|
| Eyeball | 20 | For each eye: cornea, iris, lens, retina, choroid, sclera, vitreous body and 3 more |
| Eyelids and tear system | 22 | For each eye: the plates of both eyelids, the tear gland, the tear ducts and 6 more |
| Outer ear | 1 | Both outer ears as one part |
| Nerves of the eye socket | 37 | The optic nerves and the nerves of the eye muscles |
The skull is drawn as glass, so each eyeball shows in its socket. To look inside an eye, tap the sclera and press Hide it, then do the same with the choroid.
How the eye works
Light passes through 4 parts of the eye on its way to the brain, according to the National Eye Institute.
| Part | What it does | In the model |
|---|---|---|
| Cornea | The clear dome at the front, which bends light | 1.4 cm across |
| Pupil and iris | The iris controls how much light enters through the pupil | Iris, 1.3 cm across |
| Lens | Works with the cornea to focus light on the retina | 1.0 cm across |
| Retina | Light-sensitive tissue that turns light into electrical signals | Lines the back of each eyeball |
The optic nerve then carries the signals to the brain. It is a bundle of more than 1 million nerve fibers. The macula is a small area of the retina needed for central vision, and the vitreous is the clear gel that fills the eye.
Six muscles move each eyeball: 4 rectus muscles and 2 oblique muscles. The model lists them with the muscular system, so they show in the 3D muscular system view and in the full 3D anatomy.
How the ear works
Hearing turns sound waves into electrical signals in a series of steps, according to the National Institute on Deafness and Other Communication Disorders.
| Part of the ear | What happens there | In the model |
|---|---|---|
| Outer ear | Sound travels through the ear canal to the eardrum | Yes, the outer ears |
| Middle ear | The eardrum passes vibrations to 3 small bones | No |
| Inner ear | The cochlea turns the vibrations into electrical signals | No |
The 3 bones are the malleus, the incus and the stapes. The cochlea is a fluid-filled structure shaped like a snail. Hair cells along its length detect different pitches, and the auditory nerve carries their signals to the brain.
What the model leaves out
Of the ear, the model has the outer ears only. The eardrum, the 3 small bones and the inner ear are missing. The eyes are those of one adult man.
The brain that the optic nerves run to is in the 3D nervous system. The 6 muscles of each eye are in the 3D muscular system, and the skin of the eyelids is part of the 3D skin view.