What Are the Extraocular Muscles?

Extraocular muscles are the muscles attached to the outside of the eyeball, as opposed to the intraocular muscles (ciliary muscles, pupils, and sphincter).

Extraocular muscle

Extraocular muscles are muscles that attach to the outside of the eye

Any eye movement is not the function of a single extraocular muscle, but is completed by all extraocular muscles. The eyes can maintain normal eye position, and the active muscles, antagonist muscles, and spouse muscles work so harmoniously and coordinately because the extrafrontal muscles maintain their own tension, from the cerebellum and other balances under the control of the left frontal eye movement center. Organ excitability.
The law of interactive nerve supply between the active and antagonist muscles of an eye. When the active muscles contract nerve impulses, the antagonist muscles are also inhibited and relaxed. In addition, the rotation of the eyeball from one position to any position is performed with the minimum energy and the fastest speed, and a certain angle between the visual axis and the axis of rotation of the eyeball must be maintained.
With each eye movement, the intensity of nerve impulses received by both eyes is equal. This rule of receiving equal nerve impulses between spouse muscles during two-eye movement is another important principle in addition to Shenmington's in ophthalmology. According to this, once there is a dysfunction in a certain extraocular muscle, in order to strengthen all the muscles to send out stronger nerve impulses, they will reach their spouse muscles, making the spouse muscles too strong, showing the second clinically paralytic strabismus. The oblique viewing angle is greater than the first oblique viewing angle.

In the visual activity, in order to maintain the monocular vision of the eyes, whether the two eyes are anisotropic movements (separate, gather) in looking far and near; or fast saccades in order to find a target or in the target of interest The same direction of slow visual tracking can not be separated from the brain eye movement center following the above rules, dominating the balance and coordinated movement of the extraocular muscles of the two eyes.

In the same direction movement, the eyes are like two horses with 12 reins, under the unified control of the coachman (brain), moving in one direction at the same time. When turning, each horse's reins are tightened at the same time, and the other The reins on one side must be relaxed at the same time for smooth travel. Functional extraocular muscle muscle imbalance caused by any reason clinically, or abnormalities of the extraocular muscle due to abnormalities in the central, peripheral nerves, extraocular muscles or muscle joints, causing paralysis of one or more extraocular muscles. Coordinating movement and not being able to maintain normal eye position can cause binocular monocular dysfunction. ^[2]