Anatomy of the eye


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Anatomy of the eye



Bones of the cranium

Anatomy of the cranial base

Anatomy of the orbit

Anatomy of the eye

Anatomy of the nose and paranasal sinuses

Anatomy of the oral cavity

Anatomy of the temporomandibular joint and muscles of mastication

Muscles of the face and scalp

Anatomy of the salivary glands

Nerves and vessels of the face and scalp

Anatomy of the tongue

Anatomy of the pterygopalatine (sphenopalatine) fossa

Anatomy of the inner ear

Anatomy of the infratemporal fossa

Anatomy clinical correlates

Anatomy clinical correlates: Skull, face and scalp

Anatomy clinical correlates: Eye

Anatomy clinical correlates: Ear

Anatomy clinical correlates: Temporal regions, oral cavity and nose


Anatomy of the eye

Recall questions

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USMLE® Step 1 questions

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Figure 1: Anatomy of the eye, A. Sagittal view. B. Anatomy of the left retina.
Figure 2: Anatomy of the lens and ciliary body, anterolateral view.


USMLE® Step 1 style questions USMLE

of complete

A patient is being evaluated for a suspected brain tumor. They state that they can see objects clearly when they are far away, but they are unable to focus on objects that are close to them. What nerve is most likely affected, resulting in this patient’s difficulty with accommodation?



Evan Debevec-McKenney

Alaina Mueller

Elizabeth Nixon-Shapiro, MSMI, CMI

To be able to see everything that surrounds us, including this video, we can count on two very special sense organs: the eyes. The eyes can be easily injured, so each of them is protected by a hard bony structure called the orbit. The orbits also protect the muscles, vessels and nerves of the eyes. And between each eye and the orbit protecting it, there’s a soft cushion of fat to prevent any friction or damage to the eyes. Additional protection is ensured by the lacrimal apparatus, which secretes tears to lubricate the eyes, and the eyelids, which close and open as needed.

Okay, now, if you look at a sagittal cut of the eyeball, you’ll see it’s shaped like two spheres fused, a bigger posterior one and a smaller anterior one, both with liquid inside. To keep this shape, the eyeball needs a solid structure: the fibrous layer, which is made of dense connective tissue and forms the skeleton of the eyeball. This layer has two parts: the one that makes the outer layer of the smaller sphere, called the cornea; and the one that makes the outer layer of the bigger sphere, called the sclera. The cornea is transparent and located at the anterior end of the eyeball. It allows light to pass through to the interior of the eyeball. Have you ever needed to use eye drops? Were you able to do that without instinctively closing your eyes once the drop touches your eye? The involuntary blinking is actually because of the corneal reflex! See, when something touches or irritates the cornea, it is  sensed by the ophthalmic nerve, a branch of cranial nerve V.  This sensory signal then reaches the brain stem, and signals the facial nerve, cranial nerve VII, to contract the orbicularis oculi to close our eyes. Now, the sclera is opaque and makes the white shell of the eyes. It occupies the majority of the posterior  eyeball and serves for attachment of the extrinsic muscles of the eye. Also, the sclera is pierced by the optic nerve at the posterior end of the eyeball. The place where the cornea and the sclera meet, is called the corneoscleral junction.


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