Table of Contents
Human Extraocular Muscles
The six muscles that control eye movement are called the extraocular muscles. They are attached to the outside of the eyeball and work to move the eyeball up, down, left, right, inward, and outward. The extraocular muscles are: the medial rectus, the lateral rectus, the inferior rectus, the superior rectus, the inferior oblique, and the superior oblique.
Eye Movements
Eye movements are a result of the brain trying to maintain visual stability. The brain does this by sending messages to the eye muscles to adjust the position of the eyes. There are six muscles that control the position of the eye. These muscles are: the four rectus muscles and the two oblique muscles. The rectus muscles are the muscles that attach to the front of the eye. The oblique muscles are the muscles that attach to the side of the eye.
Muscles of Eye Movement
The six muscles that control eye movement are the four rectus muscles and the two oblique muscles. The rectus muscles are the medial and lateral rectus muscles, and the oblique muscles are the superior and inferior oblique muscles. The rectus muscles are responsible for primary eye movement, and the oblique muscles are responsible for secondary eye movement.
Recti Muscles
The recti muscles are a pair of muscles that run down the front of the abdomen. They are responsible for straightening the torso and helping to move the trunk forward. The recti muscles are also used in breathing, and they help to expel air from the lungs.
Extrinsic Eye Muscles
The extrinsic eye muscles are six muscles that attach to the outside of the eyeball and control its movement. These muscles are: the lateral rectus, medial rectus, superior rectus, inferior rectus, superior oblique, and inferior oblique.
Oblique Muscles
There are four oblique muscles: the external oblique, the internal oblique, the transverse abdominis, and the pyramidalis.
The external oblique is the most superficial of the four muscles. It originates on the lateral surface of the ribs and inserts on the iliac crest and the inguinal ligament. The internal oblique is deeper than the external oblique and originates on the medial surface of the ribs. It inserts on the iliac crest and the inguinal ligament. The transverse abdominis is the deepest of the four muscles. It originates on the lumbar vertebrae and the iliac crest and inserts on the pubic bone. The pyramidalis is a small, triangular muscle that originates on the pubic bone and inserts on the linea alba.
The oblique muscles are responsible for lateral flexion of the trunk and rotation of the trunk.
Superior Oblique Muscle Action
The superior oblique muscle is responsible for rotating the eyeball downwards and outwards. It is the only muscle in the orbit that can do this. It arises from the roof of the orbit and inserts into the lateral surface of the eyeball just beneath the upper eyelid. The superior oblique muscle is innervated by the superior division of the oculomotor nerve (CN III).
Inferior Oblique
The inferior oblique muscle is a small, thin muscle that arises from the lower border of the anterior surface of the eyeball, just below the inferior rectus muscle. It inserts into the upper border of the posterior surface of the eyeball, in the area of the optic nerve. The inferior oblique muscle is innervated by the inferior oblique muscle, which is a branch of the oculomotor nerve ( Cranial Nerve III ).
The primary function of the inferior oblique muscle is to rotate the eyeball outward ( abducted ), as in looking up or to the side. It also helps to control the shape of the lens of the eye and the amount of light that enters the eye.
