The origin of the lateral rectus (LR) is an area of the eye known as the annulus of Zinn. The muscle originates from a tendinous ring surrounding the optic nerve.
LR Inserts into the lateral aspect of the eye on the fibrous layer, more specifically the sclera.
It is innervated by the abducens nerve or cranial nerve VI. Its vascular supply varies but can include branches of the ophthalmic artery, the inferior muscular artery, and lacrimal artery.
“Open chain” function of the LR is to move the eye lateral away from the nose. This motion is known as abduction.
Additional functions of LR include assisting the eye in tracking objects. Remember the eyes SHOULD move to a visual target first, then the head and neck. LR also plays an important part in both the vestibular ocular reflex and cervical ocular reflex. These reflexes are integral parts of the balance system.
Weakness in LR may lead to eye strain or strabismus. This may occur due to or be perpetuated by post-concussion syndrome.
Common complaints include eye strain, difficulty reading, and tracking objects, as well as recurrent temporal headaches.
In cases of reading difficulties, learning disability or head injury it’s important to have the function of all of the eye muscles including LR examining. This is done differently than looking at an eye chart which assesses something called visual acuity.
When was the last time you had your eye function checked?