What is extra ocular muscles?

The extraocular muscles are the six muscles that control the movements of the eyes. For reasons we don’t fully understand, these muscles can be particularly affected by myasthenia.

What is extra ocular movement?

The extraocular muscles execute eye movements and are innervated by three cranial nerves. Contraction of the medial rectus pulls the eye towards the nose (adduction or medial movement). Contraction of the lateral rectus pulls the eye away from the nose (abduction or lateral movement).

What is unique about the extra ocular muscles?

The extraocular muscles (EOMs) have unique functional and structural properties that truly set them apart from the other skeletal muscles in the body. Their most outstanding feature is a distinct behavior in disease.

What is the function of extrinsic eye muscles?

Extrinsic eye muscles (also called extraocular muscles) are attached to the outside of the eyeball and enable the eyes to move in all directions of sight. There are six extraocular eye muscles and one muscle that controls movement in the upper eyelid.

What is the function of the eyelid and eyelashes?

An eyelid is a thin layer of skin that covers and protects the eye. The eye contains a muscle that retracts the eyelid to “open” the eye either voluntarily or involuntarily. Human eyelids contain a row of eyelashes that protect the eye from dust particles, foreign bodies, and perspiration.

What is the secondary function of superior oblique muscle?

Trochlear Nerve Palsies The superior oblique muscle’s primary action is eye intorsion, with secondary and tertiary actions being eye depression and abduction, respectively.

What is the secondary action of medial rectus?

MUSCLE	PRIMARY ACTION	SECONDARY ACTION
Medial Rectus	Adduction
Lateral Rectus	Abduction
Inferior Rectus	Depression	Excycloduction (Extortion)
Superior Rectus	Elevation	Incycloduction (Intortion)

What is the function of the superior oblique muscle?

These muscles are unique in that they do not originate from the common tendinous ring, have an angular attachment to the eyeball, and they attach to the posterior aspect of the eyeball. The superior oblique functions explicitly to move the eye in the down-and-out position and intort the eye.

What does the optic nerve do?

The optic nerve is a bundle of more than 1 million nerve fibers that carry visual messages. You have one connecting the back of each eye (your retina) to your brain. Damage to an optic nerve can cause vision loss.

How many ocular muscles control the movement of the eye?

The contributions of the six extraocular muscles to vertical and horizontal eye movements. Horizontal movements are mediated by the medial and lateral rectus muscles, while vertical movements are mediated by the superior and inferior rectus and the superior (more…)

How do the extraocular eye muscles differ in action from the intrinsic eye muscles?

How do the extrinsic eye muscles differ in action from the intrinsic eye muscles? The extrinsic muscles cause faster movements than do the intrinsic muscles. Extrinsic eye muscles move the eyeball in relation to the rest of the body, whereas intrinsic muscles move structures within the eyeball.

How does the eyelid work?

The main role of the eyelids is to protect the eye. It’s vital that the surface of the eye (the cornea) remains constantly moist, so the eyelid is responsible for spreading the tear film evenly across the surface. When we sleep, the eyelids don’t simply block out light, they keep the cornea from drying out.