Eye Muscles

What are the muscles of the eye?

Both of your eyes have six muscles that control movement. These muscles are how you can direct your eyes side-to-side, up and down or at diagonal angles. The muscles that control eye movement all attach to the outside of your eyeball, which is why experts sometimes refer to them as “external” or “extrinsic” muscles.

While the external muscles mainly control which way your eyes point, they also play a role in how well you see. Your eyes need to move in ways that synchronize. If they don’t, you won’t be able to use certain visual capabilities like depth perception and three-dimensional (3D) vision.

What are the muscles of the eye?

There are two types of muscles, the rectus muscles and oblique muscles.

Each eye has four rectus muscles. Their names and locations are:

• Superior rectus: Top (“superior” means “up” or “top”).
• Inferior rectus: Bottom (“inferior” means “down” or “bottom”).
• Medial rectus: The side closest to your nose ("medial” means “middle,” as in closer to your nose).
• Lateral rectus: The side farthest from your nose (“lateral” here means “to the side,” like where your ears are).

Each eye also has two oblique muscles.

• Superior oblique: This muscle works like a pulley, starting at the upper back of your eye and extending forward, then threading through a small bony opening on the upper-inner side of your eye socket called the trochlea. After it passes through the trochlea, it attaches to the top of your eyeball just behind the superior rectus.
• Inferior oblique: The inferior oblique attaches to the lower-inner side of your eye socket. From there, it extends laterally (away from your nose), wraps around the bottom of your eye and attaches just behind the lateral rectus on the far side.

How do eye muscles work?

The six external muscles of your eyes work in pairs. When one muscle moves, its partner in the same eye helps control and balance that movement. That’s why your eyes can only turn so far.

There’s also another type of paired movement that happens involving both of your eyes. Experts call this “yoking” because your eyes turn together like a pair of horses or oxen yoked together. That’s how your eyes turn in unison.

Nerves that control these muscles

The muscles that control your eye movement depend on signals that travel through three cranial nerves:

• Cranial nerve III (CN III): This is also known as the oculomotor nerve. It controls the movements of the superior, inferior and medial rectus muscles, and also the inferior oblique muscle.
• Cranial nerve IV (CN IV): This is known as the trochlear nerve. It controls the superior oblique muscle.
• Cranial nerve VI (CN VI): This is the abducens nerve. It controls the lateral rectus muscle.

What are the common conditions and disorders that affect your eye muscles?

There are two main forms that eye muscle conditions can take:

• Muscle disorders.
• Nervous system-related disorders.

Your eye muscles are also vulnerable to injuries of the eye, skull or other surrounding tissues. In some cases, eye muscles can get stuck in the crack of a skull fracture. That’s called “entrapment,” and it’s a medical emergency. It may need immediate surgery to prevent permanent damage or other serious complications.

Muscle disorders

Some of these conditions are diseases that directly weaken muscles. These conditions can be ones you inherit, or they can develop spontaneously (either before you’re born or at some point during your life).

Examples of muscle disorders that affect eye movement include:

• Myotonic dystrophy.
• Oculopharyngeal muscular dystrophy (OPMD).
• Kearns-Sayre syndrome.
• Myositis.
• Thyroid eye disease or Graves’ disease.
• Strabismus (eye misalignment) or amblyopia (lazy eye).
• Certain types of cancers (but this is rare).

Nervous system-related disorders

Your eye muscles depend on the nerves that link them to your brain. Conditions that damage any of the three cranial nerves or your brain itself can affect how you move your eyes.

Cranial nerve palsies are a specific type of nervous system-related muscle disorder. They can affect any of the three cranial nerves, but sixth (abducens) nerve palsy is the most common form. You can have some of these at birth, but most of them develop at some point during your life (usually because of an injury or other condition).

Other nervous system-related disorders that can affect eye movement include:

• Myasthenia gravis.
• Multiple sclerosis.
• Stroke and transient ischemic attacks (TIAs).
• Tumors and cancers of the brain, or that affect the cranial nerves that connect to eye muscles.
• Nerve or brain lesions, or inflammation from infections (like Lyme disease).
• Migraines.
• Parkinson’s disease and parkinsonism.

What are some common symptoms of eye muscle conditions?

The most common symptoms of eye movement conditions include:

• Droopy eyelid (ptosis).
• Nystagmus (jerky side-to-side or spiral eye movements).
• Eye misalignments that happen when using both eyes, like exotropia and esotropia.
• Eye misalignments that happen with one eye covered, like exophoria and esophoria.
• One eye not moving when you try to look to one side (intranuclear ophthalmoplegia).

Some symptoms happen because your eyes can’t align properly or move in sync with each other. Examples include:

• Binocular vision dysfunction.
• Double vision (diplopia).
• Blurred vision.
• Dizziness.
• Vertigo.
• Motion sickness, or nausea and/or vomiting.
• Eye strain (asthenopia).

What are some common tests to check eye muscle health and function?

One of the most useful tools for checking eye muscle function is a neurological exam. Part of a neurological exam involves making you move your eyes in specific ways. If your eyes don’t move or react as they should, that can be a key clue to finding and diagnosing an otherwise invisible condition.

There are also a number of lab tests that may help diagnose eye muscle disorders. These usually involve blood tests, looking for specific antibodies or other markers. Thyroid disorders and immune diseases are both examples of condition types where lab tests are key for a diagnosis.

Common treatments for eye muscle disorders

The treatments for eye muscle disorders vary widely. Some of the conditions that affect your eye muscles will get better on their own. When an eye movement issue happens because of an underlying condition, treating that condition may be enough to resolve the eye movement issue, too.

Some eye movement conditions need more direct treatment. Some treatment options include:

• Medications. These medications depend mainly on the condition you need treatment for, but other factors can play a role, too.
• Surgery. When other treatments aren’t as effective as needed, surgery may be able to help you. They’re usually not the first option because surgery is a more invasive procedure.

Your eye care specialist or another healthcare provider can tell you more about the treatment options available for your specific case. They can tailor that information so it lines up with your medical history, personal needs and preferences.

How can I take care of my eye muscles?

The main things you can do to help preserve and maintain eye muscle health are:

• Get regular eye exams. Your eye care specialist is trained to spot eye alignment and eye muscle issues that the average person wouldn’t know to look for.
• Wear eye protection. Injuries to your eye, face or head can affect your eye muscles and keep them from working properly. Wearing the right type of eye protection, like goggles or impact-resistant glasses, can spare you from serious or even permanent injuries and damage.

When do I need to get medical care for eye movement issues?

Eye movement issues can be signs of very serious conditions, including some that are dangerous or deadly. If you have trouble moving your eyes under any of the following circumstances, you should get emergency medical attention:

• If they happen suddenly. Any sudden changes in eye movement control or vision need immediate medical attention.
• After any kind of impact or injury to your head or face. Skull fractures and other injuries can affect eye muscle movement, and it’s a medical emergency when they do.
• If you have any symptoms of a stroke. These include one-sided weakness or paralysis in your arms or legs, trouble talking or understanding others, or a facial droop.

A good rule of thumb to remember is when in doubt, don’t delay treatment. Quick diagnosis and treatment can make a huge difference in the outcome of your situation.