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The lateral rectus is the only muscle supplied by the abducens nerve (CN VI). The neuron cell bodies are located in the abducens nucleus in the pons.These neurons project axons as the abducens nerve which exit from the pontomedullary junction of the brainstem, travels through the cavernous sinus and enter the orbit through the superior orbital fissure.
The last muscle is the inferior oblique, which originates at the lower front of the nasal orbital wall, passes inferiorly over the inferior rectus muscle on its path laterally and posteriorly, and inserts under the lateral rectus muscle on the lateral, posterior part of the globe. Thus, the inferior oblique pulls the eye upward and laterally.
The abducens nucleus contains two types of cells: motor neurons that control the lateral rectus muscle on the same side, and interneurons that cross the midline and connect to the contralateral oculomotor nucleus (which controls the medial rectus muscle of the opposite eye). In normal vision, lateral movement of one eye (lateral rectus muscle ...
rectus, medial: head, eye, orbit (left/right) annulus of Zinn at orbital apex 5.5 mm medial to corneal limbus: ophthalmic artery: oculomotor nerve [CNIII], inferior branch: adducts eye: Oblique Superior and inferior 2 1 rectus, lateral: head, eye, orbit (left/right) annulus of Zinn at orbital apex 7 mm temporal to corneal limbus: ophthalmic artery
the ipsilateral abducens (CN VI) nucleus (which controls the ipsilateral lateral rectus muscle), (through the medial longitudinal fasciculus) the contralateral oculomotor (CN III) nucleus (specifically the population of its neurons that innervate the contralateral medial rectus muscle).
In a sixth nerve palsy one would expect that, over the 6 month observation period, most patients would show the following pattern of changes to their ocular muscle actions: firstly, an overaction of the medial rectus of the affected eye, then an overaction of the medial rectus of the contraletral eye and, finally, an underaction of the lateral ...
The trochlear nerve controls the superior oblique muscle to rotate the eye along its axis in the orbit medially, which is called intorsion, and is a component of focusing the eyes on an object close to the face. The oculomotor nerve controls all the other extraocular muscles, as well as a muscle of the upper eyelid. [3]
When moving the eyes to locate an object in the horizontal plane, or to track movement horizontally in the visual field, the lateral rectus muscle of one eye and medial rectus muscle of the other eye are both active. The lateral rectus is controlled by neurons of the abducens nucleus in the superior medulla, whereas the medial rectus is ...