The Six Muscles of the Eye
The human
eye has six eye muscles. They are split into two primary
groups: the recti muscles and the oblique muscles. The four recti muscles are
the lateral rectus, the medial rectus, the inferior rectus, and the superior
rectus while the two oblique muscles are the inferior oblique and the superior
oblique.
In this post, we’ll
talk about each of the six muscles and discover their function and purpose in
the human eye.
Lateral
Rectus
The lateral rectus is
a muscle of the eye’s orbit. The main function of this muscle is to pull the
pupil away from the midline of the body. The word lateral rectus comes from the
Latin latus, meaning “side” and rectus, “straight.”
Here is more in-depth information on the lateral rectus muscle:
“The lateral rectus
originates at the lateral part of the annulus of Zinn, also known as the
annular tendon or common tendinous ring, and inserts into the temporal side of
the eyeball. The annulus of Zinn is a tendinous ring that surrounds the optic
nerve and serves as the origin for four of the six extraocular muscles,
excluding the inferior oblique muscle and superior oblique muscle.” (We got
that quote from Wikipedia.)
Medial
Rectus
The medial rectus is
also a muscle of the eye’s orbit. The only function of the medial rectus is to
bring the pupil closer to the midline of the body. The word medial rectus comes
from the Latin medius, “middle.” Discover more about the
medial rectus here:
“As with most of the
muscles of the orbit, it is innervated by the inferior division of the
oculomotor nerve (Cranial Nerve III). This muscle shares an origin with several
other extrinsic eye muscles, the anulus tendineus, or common tendon. It is the
largest of the extraocular muscles and its only action is adduction of the
eyeball.” (Wikipedia)
Inferior
Rectus
The inferior rectus is
also a muscle of the orbit. This muscle has multiple functions, mainly helping
to extort the eye. The name comes from the Latin, and the word inferior means
“lower.” The muscle is on the bottom of the eye, which is why the word inferior
is used. Here are more details of the inferior rectus muscle:
“[The inferior rectus
muscle] depresses, adducts, and helps extort (rotate laterally) the eye. The
inferior rectus muscle is the only muscle that is capable of depressing the
pupil when it is in a fully abducted position.” (Wikipedia)
Superior
Rectus
The superior rectus is
mostly in charge of elevation, which means it helps you look up. It has other
functions but that is the primary one.
Again, the superior
rectus comes from Latin roots. Superior means “above” and rectus means
“straight.”The superior rectus muscle is located on the top of the eye and it
helps the eye look up, so the name is fitting.
Superior
Oblique
The superior oblique
muscle is on the upper medial side of the eye. That means it is closer to the
nose. The primary job of this muscle is to turn the eye inward. Every eye
muscle does multiple jobs, so the superior oblique does contribute to other
motions.
Inferior
Oblique
The inferior oblique
has a similar job to the inferior rectus, but it is the muscle that moves the
eye upward when the eye is looking in toward the nose, rather than away.
Isn’t it amazing to
break down the muscles of the eye to see how the individual parts come together
to move the eye smoothly and effectively?
What do you know about
the muscles of the eye? Comment any questions you have about the eye’s muscles
and we’ll answer them!
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