The nerve that opens the eyelid is the oculomotor nerve.
The oculomotor nerve helps to adjust and coordinate eye position during movement.
Several movements assist with this process: saccades, smooth pursuit, fixation, accommodation, vestibulo-ocular reflex, and optokinetic reflex.
The oculomotor nerve is the third cranial nerve (CN III).
It allows movement of the eye muscles, constriction of the pupil, focusing the eyes and the position of the upper eyelid.
Cranial nerve III works with other cranial nerves to control eye movements and support sensory functioning
The oculomotor (third) cranial nerve plays an important role in the efferent visual system by controlling ipsilateral eye movements, pupil constriction, and upper eyelid elevation.
Accordingly, damage to the third cranial nerve may cause diplopia, pupil mydriasis, and/or upper eyelid ptosis.
The oculomotor nerve innervates the superior, inferior, and medial recti, as well as the inferior oblique and levator palpebrae superioris muscles.
The axons then enter the orbit upon the short and long ciliary nerves (branches of V1, the ophthalmic division of CN V - the trigeminal nerve) to synapse on the dilator pupillae muscle, causing pupillary dilation.
The main parts of the human eye are the cornea, iris, pupil, aqueous humor, lens, vitreous humor, retina, and optic nerve.
The human eye belongs to a general group of eyes found in nature called "camera-type eyes."
Just as a camera lens focuses light onto film, a structure in the eye called the cornea focuses light onto a light-sensitive membrane called the retina.
The eye is made up of three coats, which enclose the optically clear aqueous humour, lens, and vitreous body.
The outermost coat consists of the cornea and the sclera; the middle coat contains the main blood supply to the eye and consists, from the back forward, of the choroid, the ciliary body, and the iris.
The main functions of the eyes include.
Light Detection. Every object reflects light.
Night Vision. The less light there is, the less the items will reflect for the eyes, making nighttime or darkness harder to see.
Focus. The eye, like a camera, has a lens.
Depth Perception.
Balance.
Light is focused into the eye through the clear, dome-shaped front portion of the eye called the cornea.
Behind the cornea is a fluid-filled space called the anterior chamber.
The fluid is called aqueous humor.